Universe doi: 10.3390/universe5030085

Authors: Max Niedermaier

Anti-Newtonian expansions are introduced for scalar quantum field theories and classical gravity. They expand around a limiting theory that evolves only in time while the spatial points are dynamically decoupled. Higher orders of the expansion re-introduce spatial interactions and produce overlapping lightcones from the limiting isolated world line evolution. In scalar quantum field theories, the limiting system consists of copies of a self-interacting quantum mechanical system. In a spatially discretized setting, a nonlinear &ldquo;graph transform&rdquo; arises that produces an in principle exact solution of the Functional Renormalization Group for the Legendre effective action. The quantum mechanical input data can be prepared from its 1 + 0 dimensional counterpart. In Einstein gravity, the anti-Newtonian limit has no dynamical spatial gradients, yet remains fully diffeomorphism invariant and propagates the original number of degrees of freedom. A canonical transformation (trivialization map) is constructed, in powers of a fractional inverse of Newton&rsquo;s constant, that maps the ADM action into its anti-Newtonian limit. We outline the prospects of an associated trivializing flow in the quantum theory.

]]>Universe doi: 10.3390/universe5030084

Authors: João Magueijo Lee Smolin

In this paper, we propose that cosmological time is a quantum observable that does not commute with other quantum operators essential for the definition of cosmological states, notably the cosmological constant. This is inspired by properties of a measure of time&mdash;the Chern&ndash;Simons time&mdash;and the fact that in some theories it appears as a conjugate to the cosmological constant, with the two promoted to non-commuting quantum operators. Thus, the Universe may be &ldquo;delocalised&rdquo; in time: it does not know the time, a property which opens up new cosmological scenarios, as well as invalidating several paradoxes, such as the timelike tower of turtles associated with an omnipresent time line. Alternatively, a Universe with a sharply defined clock time must have an indeterminate cosmological constant. The challenge then is to explain how islands of localized time may emerge, and give rise to localized histories. In some scenarios, this is achieved by backward transitions in quantum time, cycling the Universe in something akin to a time machine cycle, with classical flow and quantum ebbing. The emergence of matter in a sea of Lambda probably provides the ballast behind classical behaviour.

]]>Universe doi: 10.3390/universe5030083

Authors: Steven Carlip

If gravity is asymptotically safe, operators will exhibit anomalous scaling at the ultraviolet fixed point in a way that makes the theory effectively two-dimensional. A number of independent lines of evidence, based on different approaches to quantization, indicate a similar short-distance dimensional reduction. I will review the evidence for this behavior, emphasizing the physical question of what one means by &ldquo;dimension&rdquo; in a quantum spacetime, and will discuss possible mechanisms that could explain the universality of this phenomenon.

]]>Universe doi: 10.3390/universe5030082

Authors: Damianos Iosifidis Tomi Koivisto

This article presents an exhaustive classification of metric-affine theories according to their scale symmetries. First it is clarified that there are three relevant definitions of a scale transformation. These correspond to a projective transformation of the connection, a rescaling of the orthonormal frame, and a combination of the two. The most general second order quadratic metric-affine action, including the parity-violating terms, is constructed in each of the three cases. The results can be straightforwardly generalised by including higher derivatives, and implemented in the general metric-affine, teleparallel, and symmetric teleparallel geometries.

]]>Universe doi: 10.3390/universe5030081

Authors: Ingolf Bischer Thierry Grandou Ralf Hofmann

Revisiting the fast fermion damping rate calculation in a thermalized QED and/or QCD plasma in thermal equilibrium at four-loop order, focus is put on a peculiar perturbative structure which has no equivalent at zero-temperature. Not surprisingly, and in agreement with previous C ⋆ -algebraic analyses, this structure renders the use of thermal perturbation theory more than questionable.

]]>Universe doi: 10.3390/universe5030080

Authors: Tomi Koivisto Georgios Tsimperis

The observer&rsquo;s frame is the more elementary description of the gravitational field than the metric. The most general covariant, even-parity quadratic form for the frame field in arbitrary dimension generalises the New General Relativity by nine functions of the d&rsquo;Alembertian operator. The degrees of freedom are clarified by a covariant derivation of the propagator. The consistent and viable models can incorporate an ultra-violet completion of the gravity theory, an additional polarisation of the gravitational wave, and the dynamics of a magnetic scalar potential.

]]>Universe doi: 10.3390/universe5030079

Authors: Walter Dittrich

In particular, Riemann’s impact on mathematics and physics alike is demonstrated using methods originating from the theory of numbers and from quantum electrodynamics, i.e., from the behavior of an electron in a prescribed external electromagnetic field. More specifically, we employ Riemann’s zeta function to regularize the otherwise infinite results of the so-called Heisenberg–Euler Lagrangian. As a spin-off, we also calculate some integrals that are useful in mathematics and physics.

]]>Universe doi: 10.3390/universe5030078

Authors: C. R. Das L. V. Laperashvili H. B. Nielsen B. G. Sidharth

Assuming the Multiple Point Principle (MPP) as a new law of Nature, we considered the existence of the two degenerate vacua of the Universe: (a) the first Electroweak (EW) vacuum at v 1 &asymp; 246 GeV&mdash;&ldquo;true vacuum&rdquo;, and (b) the second Planck scale &ldquo;false vacuum&rdquo; at v 2 &sim; 10 18 GeV. In these vacua, we investigated different topological defects. The main aim of the paper is an investigation of the black-hole-hedgehogs configurations as defects of the false vacuum. In the framework of the f ( R ) gravity, described by the Gravi-Weak unification model, we considered a black-hole solution, which corresponds to a &ldquo;hedgehog&rdquo;&mdash;global monopole, that has been &ldquo;swallowed&rdquo; by the black-hole with mass core M B H &sim; 10 18 GeV and radius &delta; &sim; 10 &minus; 21 GeV &minus; 1 . Considering the results of the hedgehog lattice theory in the framework of the S U ( 2 ) Yang-Mills gauge-invariant theory with hedgehogs in the Wilson loops, we have used the critical value of temperature for the hedgehogs&rsquo; confinement phase ( T c &sim; 10 18 GeV). This result gave us the possibility to conclude that the SM shows a new physics (with contributions of the S U ( 2 ) -triplet Higgs bosons) at the scale &sim;10 TeV. This theory predicts the stability of the EW-vacuum and the accuracy of the MPP.

]]>Universe doi: 10.3390/universe5030077

Authors: Alexander Prygarin

In attempt to find a proper space of function expressing the eigenvalue of the color-singlet BFKL equation in N = 4 SYM, we consider an analytic continuation of harmonic sums from positive even integer values of the argument to the complex plane. The resulting meromorphic functions have pole singularities at negative integers. We derive the reflection identities for harmonic sums at weight four decomposing a product of two harmonic sums with mixed pole structure into a linear combination of terms each having a pole at either negative or non-negative values of the argument. The pole decomposition demonstrates how the product of two simpler harmonic sums can build more complicated harmonic sums at higher weight. We list a minimal irreducible set of bilinear reflection identities at weight four, which represents the main result of the paper. We also discuss how other trilinear and quadlinear reflection identities can be constructed from our result with the use of well known quasi-shuffle relations for harmonic sums.

]]>Universe doi: 10.3390/universe5030076

Authors: Davide Fermi Massimo Gengo Livio Pizzocchero

We discuss the particle horizon problem in the framework of spatially homogeneous and isotropic scalar cosmologies. To this purpose we consider a Friedmann–Lemaître–Robertson–Walker (FLRW) spacetime with possibly non-zero spatial sectional curvature (and arbitrary dimension), and assume that the content of the universe is a family of perfect fluids, plus a scalar field that can be a quintessence or a phantom (depending on the sign of the kinetic part in its action functional). We show that the occurrence of a particle horizon is unavoidable if the field is a quintessence, the spatial curvature is non-positive and the usual energy conditions are fulfilled by the perfect fluids. As a partial converse, we present three solvable models where a phantom is present in addition to a perfect fluid, and no particle horizon appears.

]]>Universe doi: 10.3390/universe5030075

Authors: Maximilian Becker Carlo Pagani

We review the study of the scaling properties of geometric operators, such as the geodesic length and the volume of hypersurfaces, in the context of the Asymptotic Safety scenario for quantum gravity. We discuss the use of such operators and how they can be embedded in the effective average action formalism. We report the anomalous dimension of the geometric operators in the Einstein&ndash;Hilbert truncation via different approximations by considering simple extensions of previous studies.

]]>Universe doi: 10.3390/universe5030074

Authors: Georgios Minas Emmanuel N. Saridakis Panayiotis C. Stavrinos Alkiviadis Triantafyllopoulos

We investigate the bounce realization in the framework of generalized modified gravities arising from Finsler and Finsler-like geometries. In particular, a richer intrinsic geometrical structure is reflected in the appearance of extra degrees of freedom in the Friedmann equations that can drive the bounce. We examine various Finsler and Finsler-like constructions. In the cases of general very special relativity, as well as of Finsler-like gravity on the tangent bundle, we show that a bounce cannot easily be obtained. However, in the Finsler&ndash;Randers space, induced scalar anisotropy can fulfil bounce conditions, and bouncing solutions are easily obtained. Finally, for the general class of theories that include a nonlinear connection, a new scalar field is induced, leading to a scalar&ndash;tensor structure that can easily drive a bounce. These features reveal the capabilities of Finsler and Finsler-like geometries.

]]>Universe doi: 10.3390/universe5030073

Authors: Vitaly A. Kudryavtsev

Weakly Interacting Massive Particle (WIMP) remains one of the most promising dark matter candidates. Many experiments around the world are searching for WIMPs and the best current sensitivity to WIMP-nucleon spin-independent cross-section is about 10 &minus; 10 pb. LUX has been one of the world-leading experiments in the search for dark matter WIMPs. Results from the LUX experiment on WIMP searches for different WIMP masses are summarised in this paper. The LUX detector will be replaced by its successor, the LUX-ZEPLIN (LZ) detector. With 50 times larger fiducial mass and an increased background rejection power due to specially-designed veto systems, the LZ experiment (due to take first data in 2020) will achieve a sensitivity to WIMPs exceeding the current best limits by more than an order of magnitude (for spin-independent interactions and for WIMP masses exceeding a few GeV). An overview of the LZ experiment is presented and LZ sensitivity is discussed based on the accurately modelled background and the high-sensitivity material screening campaign.

]]>Universe doi: 10.3390/universe5030072

Authors: Gabriele Bigongiari Oscar Adriani Sebastiano Albergo Giovanni Ambrosi Lucrezia Auditore Andrea Basti Eugenio Berti Lorenzo Bonechi Simone Bonechi Massimo Bongi Valter Bonvicini Sergio Bottai Paolo Brogi Gigi Cappello Paolo Walter Cattaneo Raffaello D’Alessandro Sebastiano Detti Matteo Duranti Mauro Fasoli Noemi Finetti Valerio Formato Maria Ionica Antonio Italiano Piergiulio Lenzi Paolo Maestro Pier Simone Marrocchesi Nicola Mori Giulio Orzan Miriam Olmi Lorenzo Pacini Paolo Papini Maria Grazia Pellegriti Andrea Rappoldi Sergio Bruno Ricciarini Antonella Sciuto Gianluigi Silvestre Oleksandr Starodubtsev Francesco Stolzi Jung Eun Suh Arta Sulaj Alessio Tiberio Alessia Tricomi Antonio Trifirò Marina Trimarchi Elena Vannuccini Anna Vedda Gianluigi Zampa Nicola Zampa

Precise measurements of the energy spectra and of the composition of cosmic rays in the PeV region could improve our knowledge regarding their origin, acceleration mechanism, propagation, and composition. At the present time, spectral measurements in this region are mainly derived from data collected by ground-based detectors, because of the very low particle rates at these energies. Unfortunately, these results are affected by the high uncertainties typical of indirect measurements, which depend on the complicated modeling of the interaction of the primary particle with the atmosphere. A space experiment dedicated to measurements in this energy region has to achieve a balance between the requirements of lightness and compactness, with that of a large acceptance to cope with the low particle rates. CaloCube is a four-year-old R&amp;D project, approved and financed by the Istituto Nazionale di Fisica Nucleare (INFN) in 2014, aiming to optimize the design of a space-borne calorimeter. The large acceptance needed is obtained by maximizing the number of entrance windows, while thanks to its homogeneity and high segmentation this new detector achieves an excellent energy resolution and an enhanced separation power between hadrons and electrons. In order to optimize detector performances with respect to the total mass of the apparatus, comparative studies on different scintillating materials, different sizes of crystals, and different spacings among them have been performed making use of MonteCarlo simulations. In parallel to simulations studies, several prototypes instrumented with CsI(Tl) (Caesium Iodide, Tallium doped) cubic crystals have been constructed and tested with particle beams. Moreover, the last development of CaloCube, the Tracker-In-Calorimeter (TIC) project, financed by the INFN in 2018, is focused on the feasibility of including several silicon layers at different depths in the calorimeter in order to reconstruct the particle direction. In fact, an important requirement for &gamma; -ray astronomy is to have a good angular resolution in order to allow precise identification of astrophysical sources in space. In respect to the traditional approach of using a tracker with passive material in front of the calorimeter, the TIC solution can save a significant amount of mass budget in a space satellite experiment, which can then be exploited to improve the acceptance and the resolution of the calorimeter. In this paper, the status of the project and perspectives for future developments are presented.

]]>Universe doi: 10.3390/universe5030071

Authors: Inyong Park

The recently proposed holography-inspired approach to quantum gravity is reviewed and expanded. The approach is based on the foliation of the background spacetime and reduction of the offshell states to the physical states. Careful attention is paid to the boundary conditions. It is noted that the outstanding problems such as the cosmological constant problem and black hole information can be tackled from the common thread of the quantized gravity. One-loop renormalization of the coupling constants and the beta function analysis are illustrated. Active galactic nuclei and gravitational waves are discussed as the potential applications of the present quantization scheme to astrophysics.

]]>Universe doi: 10.3390/universe5030070

Authors: Kyriakos Papadopoulos Nazli Kurt Basil K. Papadopoulos

A list of all possible causal relations in the two-dimensional Minkowski space M is exhausted, based on the duality between timelike and spacelike in this particular case, and thirty topologies are introduced, all of them encapsulating the causal structure of M. Generalisations of these results are discussed, as well as their significance in a discussion on spacetime singularities.

]]>Universe doi: 10.3390/universe5030069

Authors: Larissa Bravina Yurii Kvasiuk Sergey Sivoklokov Oleksandr Vitiuk Evgeny Zabrodin

Evolution of directed flow of charged particles produced in relativistic heavy-ion collisions at energies 4 &le; s &le; 19.6 GeV is considered within two microscopic transport models, ultra-relativistic quantum molecular dynamics (UrQMD) and quark-gluon string model (QGSM). In both models, the directed flow of protons changes its sign at midrapidity from antiflow to normal flow with decreasing energy of collisions, whereas the flows of mesons and antiprotons remain antiflow-oriented. For lighter colliding systems, such as Cu+Cu or S+S, changing of the proton directed flow occurs at lower bombarding energies and for more central topologies compared to a heavy Au+Au system. The differences can be explained by dissimilar production zones of different hadrons and by the influence of spectators. Directed flows of most abundant hadronic species at midrapidity are found to be formed within t = 10&ndash;12 fm/c after the beginning of nuclear collision. The influence of hard and soft mean-field potentials on the directed flow is also studied.

]]>Universe doi: 10.3390/universe5030068

Authors: Winfried Zimdahl Hermano E.S. Velten William C. Algoner

Extensions of Einstein&rsquo;s General Relativity (GR) can formally be given a GR structure in which additional geometric degrees of freedom are mapped on an effective energy-momentum tensor. The corresponding effective cosmic medium can then be modeled as an imperfect fluid within GR. The imperfect fluid structure allows us to include, on a phenomenological basis, anisotropic stresses and energy fluxes which are considered as potential signatures for deviations from the cosmological standard &Lambda; -cold-dark-matter ( &Lambda; CDM) model. As an example, we consider the dynamics of a scalar-tensor extension of the standard model, the e &Phi; &Lambda; CDM model. We constrain the magnitudes of anisotropic pressure and energy flux with the help of redshift-space distortion (RSD) data for the matter growth function f &sigma; 8 .

]]>Universe doi: 10.3390/universe5030067

Authors: Sebastián A. Franchino-Viñas Tibério de Paula Netto Omar Zanusso

We review past and present results on the non-local form-factors of the effective action of semiclassical gravity in two and four dimensions computed by means of a covariant expansion of the heat kernel up to the second order in the curvatures. We discuss the importance of these form-factors in the construction of mass-dependent beta functions for the Newton&rsquo;s constant and the other gravitational couplings.

]]>Universe doi: 10.3390/universe5020066

Authors: Marcello Rotondo Yasusada Nambu

We consider the conditioning of the timeless solution to the Wheeler&ndash;DeWitt equation by a predefined matter clock state in the simple scenario of an FLRW universe. The resulting evolution of the geometrodynamical degree of freedom with respect to clock time is characterized by the &ldquo;Berry connection&rdquo; of the reduced geometrodynamical space, which relies on the coupling of the clock with the geometry. When the connection vanishes, the standard Schr&ouml;dinger equation is obtained for the geometry with respect to clock time. When one considers environment-induced decoherence in the semiclassical limit, this condition is satisfied, and clock time coincides with cosmic time. Explicit results for the conditioned wave functions for minimal clocks made up of two quantum harmonic oscillator eigenstates are shown.

]]>Universe doi: 10.3390/universe5020065

Authors: Matteo Sanguineti

The measurement of cosmic neutrinos is a new and unique method to observe the Universe. Neutrinos are chargeless, weakly-interacting particles that can provide information about the interior of an astrophysical object for cosmological distances. Indeed, they are a complementary probe with respect to other messengers such as multi-wavelength light and charged cosmic rays, allowing the observation of the far Universe and providing information on the production mechanism. Here, the neutrino telescopes in the Mediterranean Sea that are operating or in progress will be reviewed. The ANTARES (Astronomy with a Neutrino Telescope and Abyss environmental RESearch) detector is the largest neutrino telescope currently in operation in the Mediterranean Sea and the first operating in sea water. Some of the ANTARES results will be summarized, including diffuse, point-like, and multi-messenger source searches. Finally, the future km 3 -scale telescope KM3NeT (Cubic Kilometre Neutrino Telescope) will be described focusing on the expected performances and sensitivities.

]]>Universe doi: 10.3390/universe5020064

Authors: Jamal Jalilian-Marian

Particle production in high energy hadronic/nuclear collisions in the Bjorken limit Q 2 , s &rarr; &infin; can be described in the collinear factorization framework of perturbative Quantum ChromoDynamics (QCD). On the other hand in the Regge limit, at fixed and not too high Q 2 with s &rarr; &infin; , a k &perp; factorization approach (or a generalization of it) is the appropriate framework. A new effective action approach to QCD in the Regge limit, known as the Color Glass Condensate (CGC) formalism, has been developed which allows one to investigate particle production in high energy collisions in the kinematics where collinear factorization breaks down. Here we give a brief overview of particle production in CGC framework and the evolution equation which governs energy dependence of the observables in this formalism. We show that the new evolution equation reduces to previously known evolution equations in the appropriate limits.

]]>Universe doi: 10.3390/universe5020063

Authors: Kyrill Bugaev Aleksei Ivanytskyi Violetta Sagun Boris Grinyuk Denis Savchenko Gennady Zinovjev Edward Nikonov Larissa Bravina Evgeny Zabrodin David Blaschke Arkadiy Taranenko Ludwik Turko

We review the recent approach to model the hadronic and nuclear matter equations of state using the induced surface tension concept, which allows one to go far beyond the usual Van der Waals approximation. Since the obtained equations of state, classical and quantum, are among the most successful ones in describing the properties of low density phases of strongly interacting matter, they set strong restrictions on the possible value of the hard-core radius of nucleons, which is widely used in phenomenological equations of state. We summarize the latest results obtained within this novel approach and perform a new detailed analysis of the hard-core radius of nucleons, which follows from hadronic and nuclear matter properties. Such an analysis allows us to find the most trustworthy range of its values: the hard-core radius of nucleons is 0.3–0.36 fm. A comparison with the phenomenology of neutron stars implies that the hard-core radius of nucleons has to be temperature and density dependent. Such a finding is supported when the eigenvolume of composite particles like hadrons originates from their fermionic substructure due to the Pauli blocking effect.

]]>Universe doi: 10.3390/universe5020062

Authors: Yongmin Cho

We discuss the importance of the color reflection symmetry of the Abelian decomposition in QCD. The Abelian decomposition breaks up the color gauge field to three parts, the neuron, chromon, and the topological monopole, gauge independently. Moreover, it refines the Feynman diagram in such a way that the conservation of color is explicit. This leads us to generalize the quark model to the quark and chromon model. We show how the Abelian decomposition reduces the non-Abelian color gauge symmetry to the simple discrete 24 element color reflection symmetry which assumes the role of the color gauge symmetry and plays the central role in the quark and chromon model.

]]>Universe doi: 10.3390/universe5020061

Authors: Alexander Ayriyan David Alvarez-Castillo David Blaschke Hovik Grigorian

We develop a Bayesian analysis method for selecting the most probable equation of state under a set of constraints from compact star physics, which now include the tidal deformability from GW170817. We apply this method for the first time to a two-parameter family of hybrid equations of state that is based on realistic models for the hadronic phase (KVORcut02) and the quark matter phase (SFM &alpha; ) which produce a third family of hybrid stars in the mass&ndash;radius diagram. One parameter ( &alpha; ) characterizes the screening of the string tension in the string-flip model of quark matter while the other ( &Delta; P ) belongs to the mixed phase construction that mimics the thermodynamics of pasta phases and includes the Maxwell construction as a limiting case for &Delta; P = 0 . We present the corresponding results for compact star properties like mass, radius and tidal deformabilities and use empirical data for them in the newly developed Bayesian analysis method to obtain the probabilities for the model parameters within their considered range.

]]>Universe doi: 10.3390/universe5020060

Authors: Sergey Mironov

We study the connection between quantum and topological entanglement. We present several of the simplest examples of topological systems that can simulate quantum entanglement. We also propose to use toric cobordisms as a code space for a quantum computer.

]]>Universe doi: 10.3390/universe5020059

Authors: Fabio Ferrarotto

In this paper, we present the design and expected performance of the various detectors of the PADME experiment. The experiment design has been optimized for the detection of the final state photons produced along with a “Dark Photon”, decaying to invisible particles, in the annihilation a of 550 MeV positron with an atomic electron of a thin target. The PADME experiment has been built in a new dedicated experimental hall at the Beam Test Facility (BTF) of the INFN Frascati National Laboratories and has been taking data since the third quarter of 2018.

]]>Universe doi: 10.3390/universe5020058

Authors: C. Aris Chatzidimitriou-Dreismann

The notions of Weak Value (WV) and Two-State Vector Formalism (TSVF), firstly introduced by Aharonov and collaborators, provide a quantum-theoretical formalism of extracting new information from a system in the limit of small disturbances to its state. Here, we explore two applications to the case of non-relativistic two-body scattering with one body weakly interacting with its environment. We present a physically compelling analysis of a new quantum effect: momentum transfer deficit and an accompanying enhanced energy transfer; or, equivalently, an apparent mass-deficit of the struck body. First, incoherent inelastic neutron scattering (INS) from protons of H 2 molecules in C-nanotubes is investigated. The data of the H 2 translational motion along the nanotube shows that the neutron apparently exchanges energy and momentum with a fictitious particle with mass of 0.64 atomic mass units (a.m.u.), which is in blatant contradiction with the expected value of 2 a.m.u. Second, the same theory is applied to neutron reflectivity&mdash;which is elastic and coherent&mdash;from the interface of (single crystal) Si with H 2 O-D 2 O liquid mixtures. The data shows a striking enhanced reflectivity in a wide range of momentum transfers, which is tantamount to a momentum-transfer deficit with respect to conventional expectations. However, these effects find a natural interpretation within the WV-TSVF theoretical analysis under consideration. In summary, both scattering effects contradict conventional theoretical expectations, thus also supporting the novelty of the theoretical framework of WV and TVSF. Additionally, it should be pointed out that the two dynamical variables in the interaction Hamiltonian of the theoretical model belong to two different physical bodies.

]]>Universe doi: 10.3390/universe5020057

Authors: Parthapratim Pradhan

It has been shown by explicit and exact calculation that the geometric product formula i.e., area (or entropy) product formula of outer horizon ( H + ) and inner horizon ( H &minus; ) for charged accelerating black hole (BH) should neither be mass-independent nor quantized. This implies that the area (or entropy ) product is mass-independent conjecture has been broken down for charged accelerating BH. This also further implies that the mass-independent feature of the area product of H &plusmn; is not a generic feature at all. We also compute the Cosmic-Censorship-Inequality for this BH. Moreover, we compute the specific heat for this BH to determine the local thermodynamic stability. Under certain criterion, the BH shows the second order phase transition. Furthermore, we compute logarithmic corrections to the entropy for the said BH due to small statistical fluctuations around the thermal equilibrium.

]]>Universe doi: 10.3390/universe5020056

Authors: Florian Kuchler on behalf of the TUCAN and HeXeEDM Collaborations

Searches for permanent electric dipole moments (EDMs) of fundamental particles, atoms and molecules are promising experiments to constrain and potentially reveal beyond Standard Model (SM) physics. A non-zero EDM is a direct manifestation of time-reversal (T) violation, and, equivalently, violation of the combined operation of charge-conjugation (C) and parity inversion (P). Identifying new sources of CP violation can help to solve fundamental puzzles of the SM, e.g., the observed baryon-asymmetry in the Universe. Theoretical predictions for magnitudes of EDMs in the SM are many orders of magnitude below current experimental limits. However, many theories beyond the SM require larger EDMs. Experimental results, especially when combined in a global analysis, impose strong constraints on CP violating model parameters. Including an overview of EDM searches, I will focus on the future neutron EDM experiment at TRIUMF (Vancouver). For this effort, the TUCAN (TRIUMF Ultra Cold Advanced Neutron source) collaboration is aiming to build a strong, world leading source of ultra cold neutrons (UCN) based on a unique combination of a spallation target and a superfluid helium UCN converter. Another focus will be the search for an EDM of the diamagnetic atom 129 Xe using a 3 He comagnetometer and SQUID detection. The HeXeEDM collaboration has taken EDM data in 2017 and 2018 in the magnetically shielded room (BMSR-2) at PTB Berlin.

]]>Universe doi: 10.3390/universe5020055

Authors: Carla Cattadori on behalf of the GERDA Collaboration

Since 2010, the Gerda experiment at Laboratori Nazionali del Gran Sasso (LNGS) operates searching for neutrinoless double beta decay ( 0 ν β β ) of 76 Ge to the ground and excited states of 76 Se. 0 ν β β is an ultra-rare process whose detection would directly establish the Majorana nature of the neutrino and provide a direct measurement of its mass. Since the apparatus upgrade in 2013–2015, the collaboration released the third update of the achieved results at the Neutrino 2018 Conference. The hardware upgrade and the fine tuning of the powerful analysis tools to reconstruct the event energy and to discriminate the background allowed the achievement of the energy resolution of 3 keV and 3.6 keV for Broad Energy Germanium (BEGe) and Coaxial Germanium (Coax) detectors, respectively, and an unprecedented low background index of 0.6 · 10 - 3 cts/(keV·kg·yr) 10 - 3 cts/(keV·kg·yr) in a 230 keV netto range centered at Q β β in the exposure of 58.93 kg·yr. No evidence of the 0 ν β β decay is found at the Q β β = 2039.1 keV, and the limit of 0.9 · 10 26 yr on the half-life ( T 1 / 2 0 ν ) at 90% C.L. is set. This corresponds to the limit range for the effective Majorana neutrino mass m e e of 110–260 meV. The Gerda sensitivity in terms of background index, energy resolution and exposure is the best achieved so far in 76 Ge double beta decay experiments, the energy resolution and background in the Region Of Interest (ROI) allow Gerda to operate in a background-free regime and to set a world record.

]]>Universe doi: 10.3390/universe5020054

Authors: Victoria Volkova

We discuss whether it is possible to construct a stable, static, spherically symmetric Lorentzian wormhole in beyond Horndeski theory. The deep analogy between the cosmological bounce and wormhole scenarios is described in detail. We show explicitly that going beyond Horndeski enables one to evade the no-go theorem formulated for the wormholes in the general Horndeski case.

]]>Universe doi: 10.3390/universe5020053

Authors: Astrid Eichhorn Tim Koslowski Antonio D. Pereira

A background-independent route towards a universal continuum limit in discrete models of quantum gravity proceeds through a background-independent form of coarse graining. This review provides a pedagogical introduction to the conceptual ideas underlying the use of the number of degrees of freedom as a scale for a Renormalization Group flow. We focus on tensor models, for which we explain how the tensor size serves as the scale for a background-independent coarse-graining flow. This flow provides a new probe of a universal continuum limit in tensor models. We review the development and setup of this tool and summarize results in the two- and three-dimensional case. Moreover, we provide a step-by-step guide to the practical implementation of these ideas and tools by deriving the flow of couplings in a rank-4-tensor model. We discuss the phenomenon of dimensional reduction in these models and find tentative first hints for an interacting fixed point with potential relevance for the continuum limit in four-dimensional quantum gravity.

]]>Universe doi: 10.3390/universe5020052

Authors: Sergey Mironov

We present a brief mathematical-like formulation of the no-go theorem, useful for bouncing and wormhole solutions in Horndeski theory. The no-go theorem is almost identical in the cases of flat FLRW geometry and static, spherically symmetric setting, hence, we generalize the argument of the theorem so that it has consise and universal form. We also give a strict mathematical proof of the no-go argument.

]]>Universe doi: 10.3390/universe5020051

Authors: Jorge Alfaro Marco San Martín Joaquín Sureda

A gravitational field model based on two symmetric tensors, g μ ν and g ˜ μ ν , is studied, using a Markov Chain Monte Carlo (MCMC) analysis with the most updated catalog of SN-Ia. In this model, new matter fields are added to the original matter fields, motivated by an additional symmetry ( δ ˜ symmetry). We call them δ ˜ matter fields. This theory predicts an accelerating Universe without the need to introduce a cosmological constant Λ by hand in the equations. We obtained a very good fit to the SN-Ia Data, and with this, we found the two free parameters of the theory called C and L 2 . With these values, we have fixed all the degrees of freedom in the model. The last H 0 local value measurement is in tension with the CMB Data from Planck. Based on an absolute magnitude M V = − 19.23 for the SN, Delta Gravity finds H 0 to be 74.47 ± 1.63 km/(s Mpc). This value is in concordance with the last measurement of the H 0 local value, 73.83 ± 1.48 km/(s Mpc).

]]>Universe doi: 10.3390/universe5020050

Authors: Vladimir Dzhunushaliev Vladimir Folomeev

The approximate method of solving nonperturbative Dyson-Schwinger equations by cutting off this infinite set of equations to three equations is considered. The gauge noninvariant decomposition of SU(3) degrees of freedom into SU(2) &times; U(1) and SU(3)/(SU(2) &times; U(1)) degrees of freedom is used. SU(2) &times; U(1) degrees of freedom have nonzero quantum average, and SU(3)/(SU(2) &times; U(1)) have zero quantum average. To close these equations, some approximations are employed. Regular spherically symmetric finite energy solutions of these equations are obtained. Energy spectrum of these solutions is studied. The presence of a mass gap is shown. The obtained solutions describe quasi-particles in a quark-gluon plasma.

]]>Universe doi: 10.3390/universe5020049

Authors: Christian Farnese on behalf of the ICARUS Collaboration

The 760-ton ICARUS T600 detector has completed a successful three-year physics run at the underground LNGS laboratories, searching for atmospheric neutrino interactions and, with the CNGS neutrino beam from CERN, performing a sensitive search for LSND-like anomalous ν e appearance, which contributed to constraining the allowed parameters to a narrow region around Δ m 2 ∼ eV 2 , where all the experimental results can be coherently accommodated at 90% C.L. The T600 detector underwent a significant overhaul at CERN and has now been moved to Fermilab, to be soon exposed to the Booster Neutrino Beam (BNB) to search for sterile neutrinos within the SBN program, devoted to definitively clarifying the open questions of the presently-observed neutrino anomalies. This paper will address ICARUS’s achievements, its status, and plans for the new run and the ongoing analyses, which will be finalized for the next physics run at Fermilab.

]]>Universe doi: 10.3390/universe5020048

Authors: Robert Pisarski Vladimir Skokov Alexei Tsvelik

We give an elementary and pedagogical review of the phase diagrams which are possible in quantum chromodynamics (QCD). Herein, emphasis is upon the appearance of a critical endpoint, where disordered and ordered phases meet. In many models, though, a Lifshitz point also arises. At a Lifshitz point, three phases meet: disordered, ordered, and one in which spatially inhomogeneous phases arise. At the level of mean field theory, the appearance of a Lifshitz point does not dramatically affect the phase diagram. We argue, however, that fluctuations about the Lifshitz point are very strong in the infrared and significantly alter the phase diagram. We discuss at length the analogy to inhomogeneous polymers, where the Lifshitz regime produces a bicontinuous microemulsion. We briefly mention the possible relevance to the phase diagram of QCD.

]]>Universe doi: 10.3390/universe5020047

Authors: James Pinfold

MoEDAL is a pioneering LHC experiment designed to search for anomalously ionizing messengers of new physics. It started data taking at the LHC at a center-of-mass energy of 13 TeV, in 2015. Its ground breaking physics program defines a number of scenarios that yield potentially revolutionary insights into such foundational questions as: Are there extra dimensions or new symmetries? What is the mechanism for the generation of mass? Does magnetic charge exist? What is the nature of dark matter? After a brief introduction, we report on MoEDAL’s progress to date, including our past, current and expected future physics output. We also discuss two new sub-detectors for MoEDAL: MAPP (Monopole Apparatus for Penetrating Particles) now being prototyped at IP8; and MALL (Monopole Apparatus for very Long Lived particles), currently in the planning stage. I conclude with a brief description of our program for LHC Run-3.

]]>Universe doi: 10.3390/universe5020046

Authors: M. Mohammady Alessandro Romito

Conditional expectation values of quantum mechanical observables reflect unique non-classical correlations, and are generally sensitive to decoherence. We consider the circumstances under which such sensitivity to decoherence is removed, namely, when the measurement process is subjected to conservation laws. Specifically, we address systems with additive conserved quantities and identify sufficient conditions for the system state such that its coherence plays no role in the conditional expectation values of observables that commute with the conserved quantity. We discuss our findings for a specific model where the system-detector coupling is given by the Jaynes-Cummings interaction, which is relevant to experiments tracking trajectories of qubits in cavities. Our results clarify, among others, the role of coherence in thermal measurements in current architectures for quantum thermodynamics experiments.

]]>Universe doi: 10.3390/universe5020045

Authors: Vladimir Shevchenko

In this paper, we discuss the quantum Unruh&ndash;DeWitt detector, which couples to the field bath for a finite amount of its proper time. It is demonstrated that due to the renormalization procedure, a new dimensionful parameter appears, having the meaning of a detector&rsquo;s recovery proper time. It plays no role in the leading order of the perturbation theory, but can be important non-perturbatively. We also analyze the structure of finite time corrections in two cases&mdash;perturbative switching on, and switching off when the detector is thermalized.

]]>Universe doi: 10.3390/universe5020044

Authors: Martin Bojowald

Quantum cosmology is traditionally formulated in a minisuperspace setting, implicitly averaging fields over space to obtain homogeneous models. For universal reasons related to the uncertainty principle, quantum corrections then depend on the size of the averaging volume. In minisuperspace truncations, the value of this volume remains an arbitrary parameter devoid of physical meaning, but in an effective field theory it is identified with the infrared scale of inhomogeneous modes. Moreover, the infrared scale is running during gravitational collapse, when regions in which homogeneity remains approximately valid shrink to increasingly smaller co-moving sizes. Conceptual implications of this infrared renormalization for perturbative inhomogeneity in quantum cosmology are presented here, mainly for the example of loop quantum cosmology. Several claims made in this framework are altered by infrared renormalization.

]]>Universe doi: 10.3390/universe5020043

Authors: Nandita Raha

The anomalous magnetic moment of the muon can be both measured and computed to a very high precision, making it a powerful probe to test the Standard Model and search for new physics. The previous measurement by the Brookhaven E821 experiment found a discrepancy from the SM predicted value of about three standard deviations. The Muon g–2 experiment at Fermilab will improve the precision to 140 parts per billion compared to 540 parts per billion of E821 by increasing statistics and using upgraded apparatus. The first run of data taking has been accomplished in Fermilab, where the same level of statistics as E821 has already been attained. This paper, summarizes the current experimental status and briefly describes the data quality of the first run. It compares the statistics of this run with E821 and discusses the future outlook.

]]>Universe doi: 10.3390/universe5020042

Authors: Aniello Mennella Peter Ade Giorgio Amico Didier Auguste Jonathan Aumont Stefano Banfi Gustavo Barbaràn Paola Battaglia Elia Battistelli Alessandro Baù Benoit Bélier David G. Bennett Laurent Bergé Jean Philippe Bernard Marco Bersanelli Marie Anne Bigot Sazy Nathan Bleurvacq Juan Bonaparte Julien Bonis Emory Bunn David Burke Daniele Buzi Alessandro Buzzelli Francesco Cavaliere Pierre Chanial Claude Chapron Romain Charlassier Fabio Columbro Gabriele Coppi Alessandro Coppolecchia Rocco D’Agostino Giuseppe D’Alessandro Paolo De Bernardis Giancarlo De Gasperis Michele De Leo Marco De Petris Andres Di Donato Louis Dumoulin Alberto Etchegoyen Adrián Fasciszewski Cristian Franceschet Martin Miguel Gamboa Lerena Beatriz Garcia Xavier Garrido Michel Gaspard Amanda Gault Donnacha Gayer Massimo Gervasi Martin Giard Yannick Giraud Héraud Mariano Gómez Berisso Manuel González Marcin Gradziel Laurent Grandsire Eric Guerard Jean Christophe Hamilton Diego Harari Vic Haynes Sophie Henrot Versillé Duc Thuong Hoang Nicolas Holtzer Federico Incardona Eric Jules Jean Kaplan Andrei Korotkov Christian Kristukat Luca Lamagna Sotiris Loucatos Thibaut Louis Amy Lowitz Vladimir Lukovic Raùl Horacio Luterstein Bruno Maffei Stefanos Marnieros Silvia Masi Angelo Mattei Andrew May Mark McCulloch Maria Clementina Medina Lorenzo Mele Simon J. Melhuish Ludovic Montier Louise Mousset Luis Mariano Mundo John Anthony Murphy James David Murphy Creidhe O’Sullivan Emiliano Olivieri Alessandro Paiella Francois Pajot Andrea Passerini Hernan Pastoriza Alessandro Pelosi Camille Perbost Maurizio Perciballi Federico Pezzotta Francesco Piacentini Michel Piat Lucio Piccirillo Giampaolo Pisano Gianluca Polenta Damien Prêle Roberto Puddu Damien Rambaud Pablo Ringegni Gustavo E. Romero Maria Salatino Alessandro Schillaci Claudia G. Scóccola Stephen P. Scully Sebastiano Spinelli Guillaume Stankowiak Michail Stolpovskiy Federico Suarez Andrea Tartari Jean Pierre Thermeau Peter Timbie Maurizio Tomasi Steve A. Torchinsky Matthieu Tristram Carole E. Tucker Gregory S. Tucker Sylvain Vanneste Daniele Viganò Nicola Vittorio Fabrice Voisin Robert Watson Francois Wicek Mario Zannoni Antonio Zullo

In this paper, we describe QUBIC, an experiment that will observe the polarized microwave sky with a novel approach, which combines the sensitivity of state-of-the-art bolometric detectors with the systematic effects control typical of interferometers. QUBIC&rsquo;s unique features are the so-called &ldquo;self-calibration&rdquo;, a technique that allows us to clean the measured data from instrumental effects, and its spectral imaging power, i.e., the ability to separate the signal into various sub-bands within each frequency band. QUBIC will observe the sky in two main frequency bands: 150 GHz and 220 GHz. A technological demonstrator is currently under testing and will be deployed in Argentina during 2019, while the final instrument is expected to be installed during 2020.

]]>Universe doi: 10.3390/universe5020041

Authors: Bekir Baytaş Martin Bojowald Sean Crowe

The paradigmatic models often used to highlight cosmological features of loop quantum gravity and group field theory are shown to be equivalent, in the sense that they are different realizations of the same model given by harmonic cosmology. The loop version of harmonic cosmology is a canonical realization, while the group-field version is a bosonic realization. The existence of a large number of bosonic realizations suggests generalizations of models in group field cosmology.

]]>Universe doi: 10.3390/universe5020040

Authors: Hugo Reinhardt Davide Campagnari Markus Quandt

A novel approach to the Hamiltonian formulation of quantum field theory at finite temperature is presented. The temperature is introduced by compactification of a spatial dimension. The whole finite-temperature theory is encoded in the ground state on the spatial manifold S 1 ( L ) &times; R 2 where L is the length of the compactified dimension which defines the inverse temperature. The approach is then applied to the Hamiltonian formulation of QCD in Coulomb gauge to study the chiral phase transition at finite temperatures.

]]>Universe doi: 10.3390/universe5010039

Authors: Ion Vasile Vancea

This is the second in a series of papers investigating the formulation of the simplified Dark Matter models with graviton mediators in cosmological backgrounds. We address here the crucial problem of the fundamental observable of interest, namely the graviton spectrum in an Friedmann&ndash;Lema&icirc;tre&ndash;Robertson&ndash;Walker (FLRW) cosmological background with an arbitrary Dark Matter background component. We calculate the correction to the free graviton two-point function up to the second order in the coupling constant between the Dark Matter and the graviton in the simplified Dark Matter model with graviton mediators approach in the de Sitter space. Our result is model independent in the sense that it does not depend on the particular form of the Dark Matter fields. In addition, due to the universality of the interaction between the Dark Matter and the graviton, the result obtained here applies to the interaction between the baryonic matter and the gravitons. As an application, we discuss in detail the massive scalar Dark Matter model and calculate the first order correction to the two-point function due to two Dark Matter modes in the adiabatic regime.

]]>Universe doi: 10.3390/universe5010038

Authors: Leonid Glozman

In a local gauge-invariant theory with massless Dirac fermions, a symmetry of the Lorentz-invariant fermion charge is larger than a symmetry of the Lagrangian as a whole. While the Dirac Lagrangian exhibits only a chiral symmetry, the fermion charge operator is invariant under a larger symmetry group, S U ( 2 N F ) , that includes chiral transformations as well as S U ( 2 ) C S chiralspin transformations that mix the right- and left-handed components of fermions. Consequently, a symmetry of the electric interaction, which is driven by the charge density, is larger than a symmetry of the magnetic interaction and of the kinetic term. This allows separating in some situations electric and magnetic contributions. In particular, in QCD, the chromo-magnetic interaction contributes only to the near-zero modes of the Dirac operator, while confining chromo-electric interaction contributes to all modes. At high temperatures, above the chiral restoration crossover, QCD exhibits approximate S U ( 2 ) C S and S U ( 2 N F ) symmetries that are incompatible with free deconfined quarks. Consequently, elementary objects in QCD in this regime are quarks with a definite chirality bound by the chromo-electric field, without the chromo-magnetic effects. In this regime, QCD can be described as a stringy fluid.

]]>Universe doi: 10.3390/universe5010037

Authors: Nikolay Antonov Nikolay Gulitskiy Maria Kostenko Tomáš Lučivjanský

The renormalization group approach and the operator product expansion technique are applied to the model of a passively advected vector field by a turbulent velocity field. The latter is governed by the stochastic Navier-Stokes equation for a compressible fluid. The model is considered in the vicinity of space dimension d = 4 and the perturbation theory is constructed within a double expansion scheme in y and ε = 4 − d , where y describes scaling behaviour of the random force that enters the Navier-Stokes equation. The properties of the correlation functions are investigated, and anomalous scaling and multifractal behaviour are established. All calculations are performed in the leading order of y, ε expansion (one-loop approximation).

]]>Universe doi: 10.3390/universe5010036

Authors: Bryn Knight Liliana Caballero

Neutron captures are likely to occur in the crust of accreting neutron stars (NSs). Their rate depends on the thermodynamic state of neutrons in the crust. At high densities, neutrons are degenerate. We find degeneracy corrections to neutron capture rates off nuclei, using cross sections evaluated with the reaction code TALYS. We numerically integrate the relevant cross sections over the statistical distribution functions of neutrons at thermodynamic conditions present in the NS crust. We compare our results to analytical calculations of these corrections based on a power-law behavior of the cross section. We find that although an analytical integration can simplify the calculation and incorporation of the results for nucleosynthesis networks, there are uncertainties caused by departures of the cross section from the power-law approach at energies close to the neutron chemical potential. These deviations produce non-negligible corrections that can be important in the NS crust.

]]>Universe doi: 10.3390/universe5010035

Authors: Lisa Glaser Sebastian Steinhaus

Computer simulations allow us to explore non-perturbative phenomena in physics. This has the potential to help us understand quantum gravity. Finding a theory of quantum gravity is a hard problem, but, in the last several decades, many promising and intriguing approaches that utilize or might benefit from using numerical methods were developed. These approaches are based on very different ideas and assumptions, yet they face the common challenge to derive predictions and compare them to data. In March 2018, we held a workshop at the Nordic Institute for Theoretical Physics (NORDITA) in Stockholm gathering experts in many different approaches to quantum gravity for a workshop on &ldquo;Quantum gravity on the computer&rdquo;. In this article, we try to encapsulate some of the discussions held and talks given during this workshop and combine them with our own thoughts on why and how numerical approaches will play an important role in pushing quantum gravity forward. The last section of the article is a road map providing an outlook of the field and some intentions and goalposts that were debated in the closing session of the workshop. We hope that it will help to build a strong numerical community reaching beyond single approaches to combine our efforts in the search for quantum gravity.

]]>Universe doi: 10.3390/universe5010034

Authors: Guglielmo Baccani Lorenzo Bonechi Massimo Bongi Debora Brocchini Nicola Casagli Roberto Ciaranfi Luigi Cimmino Vitaliano Ciulli Raffaello D’Alessandro Chiara Del Ventisette Andrea Dini Giovanni Gigli Sandro Gonzi Silvia Guideri Luca Lombardi Barbara Melon Nicola Mori Massimiliano Nocentini Pasquale Noli Giulio Saracino Lorenzo Viliani

Muon absorption radiography is an imaging technique based on the measurement of the absorption of cosmic ray muons. This technique has recently been used successfully to investigate the presence of unknown cavities in the Bourbon Gallery in Naples and in the Chephren Pyramid at Cairo. The MIMA detector (Muon Imaging for Mining and Archaeology) is a prototype muon tracker for muon radiography for application in the fields of archaelogy and mining. It is made of three pairs of X-Y planes each consisting of 21 scintillator bars with a silicon photomultiplier readout. The detector is compact, robust, easily transportable, and has a low power consumption: all of which makes the detector ideal for measurements in confined and isolated environments. With this detector, a measurement from inside the Temperino mine in the San Silvestro archaeo-mining park in Tuscany was performed. The park includes about 25 km of mining tunnels arranged on several levels that have been exploited from the Etruscan time. The measured muon absorption was compared to the simulated one, obtained from the information provided by 3D laser scanner measurements and cartographic maps of the mountain above the mine, in order to obtain information about the average density of the rock. This allowed one to confirm the presence of a partially accessible exploitation opening and provided some hints regarding the presence of a high-density body within the rock.

]]>Universe doi: 10.3390/universe5010033

Authors: Liron Levy Moshe Goldstein

In recent years, tools from quantum information theory have become indispensable in characterizing many-body systems. In this work, we employ measures of entanglement to study the interplay between disorder and the topological phase in 1D systems of the Kitaev type, which can host Majorana end modes at their edges. We find that the entanglement entropy may actually increase as a result of disorder, and identify the origin of this behavior in the appearance of an infinite-disorder critical point. We also employ the entanglement spectrum to accurately determine the phase diagram of the system, and find that disorder may enhance the topological phase, and lead to the appearance of Majorana zero modes in systems whose clean version is trivial.

]]>Universe doi: 10.3390/universe5010032

Authors: Alexandros Marantis

The Fast Tracker (FTK) is a highly parallel processor dedicated to a quick and efficient reconstruction of tracks in the Pixel and Semiconductor Tracker (SCT) detectors of the ATLAS experiment at LHC. It is designed to identify charged particle tracks with transverse momentum above 1 GeV and reconstruct their parameters at an event rate of up to 100 kHz. The average latency of the processing is below 100 μs at the expected collision intensities. This performance is achieved by using custom ASIC chips with associative memory for pattern matching, while modern FPGAs calculate the track parameters. This paper describes the architecture, the current status and a High-Level Data Quality Monitoring framework of the FTK system. This monitoring framework provides an online comparison of the FTK hardware output with the FTK functional simulation, which is run on the pixel and SCT detector data at a low rate, allowing the detection of non-expected outputs of the FTK system.

]]>Universe doi: 10.3390/universe5010031

Authors: Herbert W. Hamber Lu Heng Sunny Yu

The ability to reproduce the observed matter power spectrum P ( k ) to high accuracy is often considered as a triumph of inflation. In this work, we explore an alternative explanation for the power spectrum based on nonperturbative quantum field-theoretical methods applied to Einstein&rsquo;s gravity, instead of ones based on inflation models. In particular, the power spectral index, which governs the slope on the P ( k ) graph, can be related to critical scaling exponents derived from the Wilson renormalization group analysis. We find that the derived value fits favorably with the Sloan Digital Sky Survey telescope data. We then make use of the transfer functions, based only on the Boltzmann equations, which describe states out of equilibrium, and Einstein&rsquo;s general relativity, to extrapolate the power spectrum to the Cosmic Microwave Background (CMB) regime. We observe that the results fit rather well with current data. Our approach contrasts with the conventional explanation, which uses inflation to generate the scale-invariant Harrison&ndash;Zel&rsquo;dovich spectrum on CMB scales and uses the transfer function to extrapolate it to the galaxy regime. The results we present here only assume quantum field theory and Einstein&rsquo;s gravity, and hence provide a competing explanation of the power spectrum, without relying on the assumptions usually associated with inflationary models. At the end, we also outline several testable predictions in this picture that deviate from the conventional picture of inflation and which hopefully will become verifiable in the near future with increasingly accurate measurements.

]]>Universe doi: 10.3390/universe5010030

Authors: Ignatios Antoniadis

I discuss the possibility that inflation is driven by supersymmetry breaking, with the superpartner of the goldstino (sgoldstino) playing the role of the inflaton. Imposing an R-symmetry to satisfy the slow-roll conditions, avoiding the so-called η -problem, leads to an interesting class of small field inflation models, characterised by an inflationary plateau around the maximum of scalar potential near the origin, where R-symmetry is restored with the inflaton rolling down to a minimum, describing the present phase of the Universe. Inflation can be driven by either an F- or a D-term, while the minimum has a positive tuneable vacuum energy. The models agree with cosmological observations and, in the simplest case, predict a rather small tensor-to-scalar ratio of primordial perturbations. This talk is an extended version of an earlier review (Antoniadis, 2018).

]]>Universe doi: 10.3390/universe5010029

Authors: Sérgio Costa Ulhoa Ednardo Paulo Spaniol Ronni Geraldo Gomes Amorim

In this article we calculate the total angular momentum for Kerr space-time for slow rotations in the context of teleparallel gravity. In order to analyze the role of such a quantity, we apply Weyl quantization method to obtain a quantum equation for the z-component of the angular momentum density, and for the squared angular momentum density as well. We present an approximate solution using the Adomian decomposition method (AM), which reveals a discrete characteristic for angular momentum.

]]>Universe doi: 10.3390/universe5010028

Authors: Saranya Samik Ghosh on behalf of the CMS Collaboration

The highlights of the recent activities and physics results leading up to the summer of 2018 from the Compact Muon Solenoid (CMS) experiment at the CERN Large Hadron Collider (LHC) are presented here. The CMS experiment has a very wide-ranging physics program, and only a very limited subset of the physics analyses being performed at CMS are discussed here, consisting of several important results from the analysis of proton-proton collision data at center-of-mass energy of 13 TeV. These include important analyses of Higgs boson physics, with the highlight being the first observation of the t t &macr; H production of the Higgs boson, along with analyses pertaining to precision standard model measurements, top quark physics, with the single top production cross-section measurement, and flavor physics, with the important observation of &chi; b (3P) states. Additionally, important searches for physics beyond the standard model are also presented.

]]>Universe doi: 10.3390/universe5010027

Authors: Francesco Renga Gianluca Cavoto Angela Papa Emanuele Ripiccini Cecilia Voena

The search for the Lepton Flavor Violating decay &mu; &rarr; e &gamma; exploits the most intense continuous muon beams, which can currently deliver &sim; 10 8 muons per second. In the next decade, accelerator upgrades are expected in various facilities, making it feasible to have continuous beams with an intensity of 10 9 or even 10 10 muons per second. We investigate the experimental limiting factors that will define the ultimate performances, and hence the sensitivity, in the search for &mu; &rarr; e &gamma; with a continuous beam at these extremely high rates. We then consider some conceptual detector designs and evaluate the corresponding sensitivity as a function of the beam intensity.

]]>Universe doi: 10.3390/universe5010026

Authors: Ingolf Bischer Thierry Grandou Ralf Hofmann

Revisiting the fast fermion damping rate calculation in a thermalized momentum scale eT (QED) and/or momentum scale gT (QCD) plasma at 4-loop order, focus is put on a peculiar perturbative structure which has no equivalent at zero-temperature. Not surprisingly, and in agreement with previous C ★ -algebraic analyses, this structure renders the use of thermal perturbation theory quite questionable.

]]>Universe doi: 10.3390/universe5010025

Authors: Universe Editorial Office

Rigorous peer-review is the corner-stone of high-quality academic publishing [...]

]]>Universe doi: 10.3390/universe5010024

Authors: Dag Larsen on behalf of the NA61/SHINE collaboration

The NA61/SHINE experiment studies hadron production in hadron-hadron, hadron-nucleus and nucleus-nucleus collisions. The physics programme includes the study of the onset of deconfinement and search for the critical point as well as reference measurements for neutrino and cosmic ray experiments. For strong interactions, future plans are to extend the programme of study of the onset of deconfinement by measurements of open-charm and possibly other short-lived, exotic particle production in nucleus-nucleus collisions. This new programme is planned to start after 2020 and requires upgrades to the present NA61/SHINE detector setup. Besides the construction of a large acceptance silicon detector, a 10-fold increase of the event recording rate is foreseen, which will necessitate a general upgrade of most detectors.

]]>Universe doi: 10.3390/universe5010023

Authors: Apostolos G. Tsirigotis Antonios Leisos

The design and construction of a small-area, low-cost educational cosmic ray telescope is presented. It can be operated in high-school classrooms or university laboratories. The telescope consists of three small-area scintillation detectors with all the necessary electronics for powering, control, monitoring, and data acquisition. The calibration procedures and the performance of the telescope in reconstructing Extensive Air Showers are also presented.

]]>Universe doi: 10.3390/universe5010022

Authors: Suddhasattwa Brahma Dong-han Yeom

We study the geometry of Euclidean instantons in loop quantum cosmology (LQC) such as those relevant for the no-boundary proposal. Confining ourselves to the simplest case of a cosmological constant in minisuperspace cosmologies, we analyze solutions of the semiclassical (Euclidean) path integral in LQC. We find that the geometry of LQC instantons have the peculiar feature of an infinite tail which distinguishes them from Einstein gravity. Moreover, due to quantum-geometry corrections, the small-a behaviour of these instantons seem to naturally favor a closing-off of the geometry in a regular fashion, as was originally proposed for the no-boundary wavefunction.

]]>Universe doi: 10.3390/universe5010021

Authors: Dean Karlen on behalf of the T2K Collaboration

The T2K long baseline neutrino oscillation experiment measures muon neutrino disappearance and electron neutrino appearance in accelerator-produced neutrino and anti-neutrino beams. This presentation reports on the analysis of our data from an exposure of 2.6 × 10 21 protons on target. Results for oscillation parameters, including the CP violation parameter and neutrino mass ordering, are shown.

]]>Universe doi: 10.3390/universe5010020

Authors: Yuuki Nakano On behalf of the Super-Kamiokande Collaboration

Super-Kamiokande (SK), a 50 kton water Cherenkov detector in Japan, is observing both atmospheric and solar neutrinos. It is also searching for supernova (relic) neutrinos, proton decays and dark matter-like particles. A three-flavor oscillation analysis was conducted with the atmospheric neutrino data to study the mass hierarchy, the leptonic CP violation term, and other oscillation parameters. In addition, the observation of solar neutrinos gives precise measurements of the energy spectrum and oscillation parameters. In this proceedings, we given an overview of the latest results from SK and the prospect toward the future project of SK-Gd.

]]>Universe doi: 10.3390/universe5010019

Authors: Priyanka Kirti Ranjan Ashutosh Bhardwaj

An overview of recent results of single-top quark production at the LHC using data collected with the CMS detector is presented. The CMS experiment has measured the electroweak production of the top quark in three production modes, namely t-channel, tW-channel, and s-channel. Measurements of the rare processes involving a single-top quark with a Z boson and a single-top quark with a &gamma; are also discussed. All measurements are in agreement with the standard model prediction, and no sign of physics beyond the standard model is observed.

]]>Universe doi: 10.3390/universe5010018

Authors: Martina Ressegotti On behalf of the CMS Collaboration

The Compact Muon Solenoid (CMS) detector is one of the two multipurpose experiments at the Large Hadron Collider (LHC). It has successfully collected data during Run 1 (2010–2013) and achieved important physics results, like the discovery of the Higgs boson announced in 2012. Willing to unravel further open questions not yet explained by the standard model, intense activities have been performed to further improve the detector and the trigger before the LHC restart in 2016 (Run 2), in parallel with the upgrade of the LHC. The achieved global performance of the CMS experiment and of several subdetectors will be presented.

]]>Universe doi: 10.3390/universe5010017

Authors: Christian Farnese

The 760-ton liquid argon ICARUS T600 detector performed a successful three-year physics run at the underground LNGS laboratories, studying in particular neutrino oscillations with the CNGS neutrino beam from CERN. This detector has been moved in 2017 to Fermilab after a significant overhauling and will be exposed soon to the Booster Neutrino Beam acting as the far station to search for sterile neutrinos within the SBN program. The contribution addresses the developed methods and the results of an analysis to identify and reconstruct atmospheric neutrino interactions collected by ICARUS T600 in the underground run at LNGS. Despite the limited statistics, this search demonstrates the excellent quality of the detector reconstruction and the feasibility of an automatic search for the electron neutrino CC interactions in the sub-GeV range, as required for the study of the BNB neutrinos at FNAL.

]]>Universe doi: 10.3390/universe5010016

Authors: Jorge Alfaro

In this paper, we want to study one loop corrections in Very Special Relativity Standard Model(VSRSM). In order to satisfy the Ward identities and the S i m ( 2 ) symmetry of the model, we have to specify the Feynman rules, including the infrared regulator. To do this, we adapt the Mandelstam&ndash;Leibbrandt (ML) prescription to incorporate external momentum-dependent null vectors. As an example, we use the new S i m ( 2 ) invariant dimensional regularization to compute one loop corrections to the effective action in the subsector of the VSRSM that describe the interaction of photons with charged leptons. New stringent bounds for the masses of &nu; e and &nu; &mu; are obtained.

]]>Universe doi: 10.3390/universe5010015

Authors: Vladimir Vechernin Evgeny Andronov

We calculate the strongly intensive observables for multiplicities in two rapidity windows in the model with independent identical strings taking into account the charge sign of particles. We express the observables through the string pair correlation functions describing the correlations between the same and opposite sign particles produced in a string decay. We extract these charge-wise string two-particle correlation functions from the ALICE data on the forward-backward correlations and the balance function. Using them we predict the behavior of the charge-wise strongly intensive observables in the model with independent identical strings. We also show that the observable between multiplicities in two acceptance windows separated in rapidity, which is a strongly intensive in the case with independent identical strings, loses this property, when we take into account string fusion effects and a formation of strings of a few different types takes place in a collision. We predict the changes in the behaviour of this observable with energy and collision centrality, arising due to the string fusion phenomena.

]]>Universe doi: 10.3390/universe5010014

Authors: Anastasia Merzlaya on behalf of the NA61/SHINE Collaboration

The study of open charm meson production provides an efficient tool for detailed investigations of the properties of hot and dense matter formed in nucleus-nucleus collisions. The interpretation of the existing data from the CERN Super Proton Synchrotron (SPS) suffers from a lack of knowledge about the total charm production rate. To overcome this limitation, the heavy-ion program of the NA61/SHINE experiment at the CERN SPS has been upgraded to allow for precise measurements of particles with a short lifetime. A new vertex detector (Small Acceptance version of the Vertex Detector (SAVD)) was constructed to meet the challenges of open charm measurements in nucleus-nucleus collisions. The first exploratory data taking of Pb + Pb collisions at 150A GeV/c with the SAVD was performed in 2016, and a D 0 signal was extracted in its D 0 → π + + K − decay channel. This was the first, direct observation of open charm in nucleus-nucleus collisions at the SPS energies. Furthermore, the future plans of open charm measurements in the NA61/SHINE experiment related to the upgraded version of the Vertex Detector are discussed.

]]>Universe doi: 10.3390/universe5010013

Authors: Jacques L. Rubin

The &lsquo;projective theory of relativity&rsquo; is a theory developed historically by Oswald Veblen and Banesh Hoffmann, Jan Arnoldus Schouten and David van Dantzig. This theory differs radically from Kaluza-Klein/conformal type theories of spacetime, although it shares with these theories geometric aspects in five-dimensional spaces. The peculiarity of the projective geometries involved in this theory was that it is based on spaces coordinated by five so-called &lsquo;homogeneous coordinates.&rsquo; Since then, no physical observables could be ascribed to these five homogeneous coordinates and, in particular, during the elaboration of this theory which consequently fell completely into oblivion. We will present how this projective theory of relativity can be fully justified physically from the causal structures and localizing protocols involved in so-called &lsquo;relativistic localizing systems&rsquo; that extend &lsquo;relativistic positioning systems.&rsquo; We explain the correspondence between &lsquo;homogeneous coordinates&rsquo; of the projective theory of relativity and the physical observables defined in relativistic localizing systems. Then, possible astrophysical manifestations will be presented based on projective effects, invariance of interactions, or observations with respect to projective transformations.

]]>Universe doi: 10.3390/universe5010012

Authors: Zacharias Roupas

The gravitational instability, responsible for the formation of the structure of the Universe, occurs below energy thresholds and above spatial scales of a self-gravitating expanding region, when thermal energy can no longer counterbalance self-gravity. I argue that at sufficiently-large scales, dark energy may restore thermal stability. This stability re-entrance of an isothermal sphere defines a turnaround radius, which dictates the maximum allowed size of any structure generated by gravitational instability. On the opposite limit of high energies and small scales, I will show that an ideal, quantum or classical, self-gravitating gas is subject to a high-energy relativistic gravothermal instability. It occurs at sufficiently-high energy and small radii, when thermal energy cannot support its own gravitational attraction. Applications of the phenomenon include neutron stars and core-collapse supernovae. I also extend the original Oppenheimer&ndash;Volkov calculation of the maximum mass limit of ideal neutron cores to the non-zero temperature regime, relevant to the whole cooling stage from a hot proto-neutron star down to the final cold state.

]]>Universe doi: 10.3390/universe5010011

Authors: Carla Sbarra On behalf of the ATLAS Collaboration

LUCID (LUminosity Cerenkov Integrating Detector) is the main luminosity monitor of the ATLAS (A Toroidal LHC Apparatus) experiment at the Large Hadron Collider (LHC) and in particular is the only one capable of providing bunch-by-bunch luminosity information, both online and offline, for all beam conditions and luminosity ranges. LUCID-2 refers to the detector upgrade designed to cope with the running conditions to be met in Run-2 (2015–2018): a center of mass energy of 13 TeV, with 50 pp interactions per bunch-crossing on average and a 25 ns bunch-spacing. This report summarizes all changes with respect to the detector deployed in Run-1 (2010–2012), including smaller sensors for higher granularity, new readout electronics for early signal digitization, and a completely new calibration concept guaranteeing long-term stability of the detector response. In addition, the overall detector performance in Run-2 and preliminary results on luminosity measurements are presented.

]]>Universe doi: 10.3390/universe5010010

Authors: Alessio Caminata Douglas Adams Chris Alduino Krystal Alfonso Frank Avignone Oscar Azzolini Giacomo Bari Fabio Bellini Giovanni Benato Andrea Bersani Matteo Biassoni Antonio Branca Chiara Brofferio Carlo Bucci Alice Campani Lucia Canonica Xi-Guang Cao Silvia Capelli Luigi Cappelli Laura Cardani Paolo Carniti Nicola Casali Davide Chiesa Nicholas Chott Massimiliano Clemenza Simone Copello Carlo Cosmelli Oliviero Cremonesi Richard Creswick Jeremy Cushman Antonio D’Addabbo Damiano D’Aguanno Ioan Dafinei Christopher Davis Stefano Dell’Oro Milena Deninno Sergio Di Domizio Valentina Dompè Alexey Drobizhev De-Qing Fang Guido Fantini Marco Faverzani Elena Ferri Fernando Ferroni Ettore Fiorini Massimo Alberto Franceschi Stuart Freedman Brian Fujikawa Andrea Giachero Luca Gironi Andrea Giuliani Paolo Gorla Claudio Gotti Thomas Gutierrez Ke Han Karsten Heeger Raul Hennings-Yeomans Roger Huang Huan Zhong Huang Joe Johnston Giorgio Keppel Yury Kolomensky Alexander Leder Carlo Ligi Yu-Gang Ma Laura Marini Maria Martinez Reina Maruyama Yuan Mei Niccolo Moggi Silvio Morganti Tommaso Napolitano Massimiliano Nastasi Claudia Nones Eric Norman Valentina Novati Angelo Nucciotti Irene Nutini Thomas O’Donnell Jonathan Ouellet Carmine Pagliarone Marco Pallavicini Luca Pattavina Maura Pavan Gianluigi Pessina Valerio Pettinacci Cristian Pira Stefano Pirro Stefano Pozzi Ezio Previtali Andrei Puiu Carl Rosenfeld Claudia Rusconi Michinari Sakai Samuele Sangiorgio Benjamin Schmidt Nick Scielzo Vivek Singh Monica Sisti Danielle Speller Luca Taffarello Francesco Terranova Claudia Tomei Marco Vignati Sachinthya Wagaarachchi Barbara Wang Bradford Welliver Jeffrey Wilson Kevin Wilson Lindley Winslow Tom Wise Luigi Zanotti Sergio Zimmermann Stefano Zucchelli

The Cryogenic Underground Observatory for Rare Events (CUORE) is the first bolometric experiment searching for neutrinoless double beta decay that has been able to reach the 1-ton scale. The detector consists of an array of 988 TeO 2 crystals arranged in a cylindrical compact structure of 19 towers, each of them made of 52 crystals. The construction of the experiment was completed in August 2016 and the data taking started in spring 2017 after a period of commissioning and tests. In this work we present the neutrinoless double beta decay results of CUORE from examining a total TeO 2 exposure of 86.3 kg yr , characterized by an effective energy resolution of 7.7 keV FWHM and a background in the region of interest of 0.014 counts / ( keV kg yr ) . In this physics run, CUORE placed a lower limit on the decay half-life of neutrinoless double beta decay of 130 Te &gt; 1.3 &middot; 10 25 yr (90% C.L.). Moreover, an analysis of the background of the experiment is presented as well as the measurement of the 130 Te 2 &nu; &beta; &beta; decay with a resulting half-life of T 1 / 2 2 &nu; = [ 7.9 &plusmn; 0.1 ( stat . ) &plusmn; 0.2 ( syst . ) ] &times; 10 20 yr which is the most precise measurement of the half-life and compatible with previous results.

]]>Universe doi: 10.3390/universe5010009

Authors: Margaret Carrington Christopher Phillips

We work with a symmetric scalar theory with quartic coupling in 4-dimensions. Using a 2PI effective theory and working at 4 loop order, we renormalize with a renormalization group method. All divergences are absorbed by one bare coupling constant and one bare mass which are introduced at the level of the Lagrangian. The method is much simpler than counterterm renormalization, and can be generalized to higher order nPI effective theories.

]]>Universe doi: 10.3390/universe5010008

Authors: Nikolaos E. Mavromatos Sarben Sarkar

On extending the Standard Model (SM) Lagrangian, through a non-linear Born&ndash;Infeld (BI) hypercharge term with a parameter &beta; (of dimensions of [mass] 2 ), a finite energy monopole solution was claimed by Arunasalam and Kobakhidze. We report on a new class of solutions within this framework that was missed in the earlier analysis. This new class was discovered on performing consistent analytic asymptotic analyses of the nonlinear differential equations describing the model; the shooting method used in numerical solutions to boundary value problems for ordinary differential equations is replaced in our approach by a method that uses diagonal Pad&eacute; approximants. Our work uses the ansatz proposed by Cho and Maison to generate a static and spherically-symmetric monopole with finite energy and differs from that used in the solution of Arunasalam and Kobakhidze. Estimates of the total energy of the monopole are given, and detection prospects at colliders are briefly discussed.

]]>Universe doi: 10.3390/universe5010007

Authors: Yuuki Nakano On behalf of the Super-Kamiokande Collaboration

We report the results from a search in Super-Kamiokande for neutrino signals coincident with gravitational-wave events using a neutrino energy range from 3.5 MeV–100 PeV. We searched for coincident neutrino events within a time window of ± 500 s around the gravitational-wave detection time. In this work, we report the number of events within the search-window and the 90 % confidence level upper limits on the neutrino fluence for each gravitational-wave event.

]]>Universe doi: 10.3390/universe5010006

Authors: Maria Vasileiou On behalf of the ALICE Collaboration

We present a comprehensive study of hadronic resonance production in pp, p-Pb and Pb-Pb collisions at different Large Hadron Collider (LHC) energies. In particular, the production of hadronic resonances, such as ρ(770)0, Κ*(892)0, φ(1020), Σ(1385)±, Λ(1520) and Ξ(1530)0 will be discussed in detail. In heavy-ion collisions, hadronic resonances are sensitive to the re-scattering and regeneration processes occurring between chemical freeze-out and kinetic freeze-out due to their short lifetimes. The measurements in pp and p-Pb collisions are used as a reference for heavy-ion collisions and to search for the onset of collective phenomena. We will report on the transverse momentum spectra, integrated yields, mean transverse momenta, particle ratios and nuclear modification factors of hadronic resonances. The results will be compared to those of other experiments, and to theoretical models and Monte Carlo generators.

]]>Universe doi: 10.3390/universe5010005

Authors: Nick E. Mavromatos Sarben Sarkar

We review scenarios of baryogenesis through leptogenesis at early epochs of the universe, in string-inspired minimal extensions of the Standard Model (SM), involving heavy right-handed Majorana neutrinos. Spontaneous violation of CPT symmetry is induced by appropriate (in general, temperature-dependent) backgrounds of the Kalb&ndash;Ramond (KR) axion field, which has its origins in the (bosonic) massless string multiplet. As interesting features of the model, we also discuss two issues associated with quantum (chiral) anomalies: (i) the non-contribution of the KR axion background to the (anomalous) chiral magnetic effect, which arises in the presence of external electromagnetic fields and non-zero chiral chemical potentials of charged fermions; and (ii) the potential role of quantum fluctuations of the KR axion on the (anomalous) radiative generation of a Majorana mass for the right-handed neutrinos themselves.

]]>Universe doi: 10.3390/universe5010002

Authors: Fabio Bellini Oscar Azzolini Maria Teresa Barrera Jeffrey Beeman Mattia Beretta Matteo Biassoni Chiara Brofferio Carlo Bucci Lucia Canonica Silvia Capelli Laura Cardani Paolo Carniti Nicola Casali Lorenzo Cassina Massimiliano Clemenza Oliverio Cremonesi Angelo Cruciani Antonio D’Addabbo Ioan Dafinei Sergio Di Domizio Fernando Ferroni Luca Gironi Andrea Giuliani Paolo Gorla Claudio Gotti Giorgio Keppel Maria Martinez Silvio Morganti Sergei Nagorny Massimiliano Nastasi Stefano Nisi Claudia Nones Donato Orlandi Lorenzo Pagnanini Marco Pallavicini Vincenzo Palmieri Luca Pattavina Maura Pavan Gianluigi Pessina Valerio Pettinacci Stefano Pirro Stefano Pozzi Ezio Previtali Andrei Puiu Claudia Rusconi Karoline Schäffner Claudia Tomei Marco Vignati Anastasia Zolotarova

CUPID-0 is the first large array of scintillating Zn 82 Se cryogenic calorimeters (bolometers) implementing particle identification for the search of the neutrinoless double beta decay (0 &nu; &beta; &beta; ). The detector consists of 24 enriched Zn 82 Se bolometers for a total 82 Se mass of 5.28 kg and it has been taking data in the underground LNGS (Italy) since March 2017. In this article we show how the dual read-out provides a powerful tool for the &alpha; particles rejection. The simultaneous use of the heat and light information allows us to reduce the background down to (3.2 &minus; 1.1 + 1.3 )&times;10 &minus; 3 counts/(keV kg year), an unprecedented level for cryogenic calorimeters. In a total exposure of 5.46 kg year Zn 82 Se we set the most stringent limit on the 0 &nu; &beta; &beta; decay 82 Se half-life T 1 / 2 0 &nu; &gt; 4.0 &times; 10 24 year at 90% C.I.

]]>Universe doi: 10.3390/universe5010004

Authors: Antonios Leisos Apostolos Tsirigotis George Bourlis Michael Petropoulos Leonidas Xiros Ioannis Manthos Spyros Tzamarias

The HELYCON project aims at the installation of cosmic air-shower detectors on the roofs of high-school buildings in western Greece. During the last four years, the HELYCON project made a substantial progress. Three HELYCON stations were installed and are still in operation at the Hellenic Open University (HOU) campus, while a small-scale air-shower detector ( &mu; Cosmics detector), suitable for in classroom operation, was developed. During the construction and operation of these detectors, many experimental tests and calibration procedures were established, offering the framework for the educational activities of the HELYCON project. In this work, we present the recent developments of the HELYCON project and describe the main aspects of the methodology we use in a five-day training program that introduces the Greek education community to the experimental procedures of HELYCON.

]]>Universe doi: 10.3390/universe5010003

Authors: Antonios Leisos Stavros Nonis Apostolos Tsirigotis George Bourlis Kostas Papageorgiou Ioannis Gkialas Ioannis Manthos Spyros Tzamarias

The Astroneu array comprises 9 large charged particle detectors and 3 RF antennas arranged in three autonomous stations operating at the University Campus of the Hellenic Open University in the city of Patras. Each station of the array detects extensive air showers with primary energy threshold of about 10 TeV, while double station coincidence events select showers with energies higher than 10 3 TeV. In such an environment, the radio detection of air showers is challenging. The RF signals besides being extremely weak they also suffer from strong human made electromagnetic noise. In this work, we present the analysis of double station coincidence events and we study the correlation of the RF data with the particle detectors data. We use the experimental information from the particle detectors and the antennas to select very high energy showers and we compare the timing of the RF signals with the timing of the particle detector signals as well as the strength of the RF signals with the simulation predictions.

]]>Universe doi: 10.3390/universe5010001

Authors: Richard Kerner

If the reality underlying classical physics is quantum in nature, then it is reasonable to assume that the transformations of fields, currents, energy, and momentum observed macroscopically are the result of averaging of symmetry groups acting in the Hilbert space of quantum states of elementary constituents of which classical material bodies are formed. We show how Pauli&rsquo;s exclusion principle based on the discrete Z 2 symmetry group generates the S L ( 2 , C ) symmetry of the space of states of an electron endowed with spin. Then, we generalize this reasoning in the case of quark colors and the corresponding Z 3 symmetry. A ternary generalization of Dirac&rsquo;s equation is proposed, leading to self-confined quarks states. It is shown how certain cubic or quadratic combinations can form freely-propagating entangled states. The entire symmetry of the standard model, S U ( 2 ) &times; U ( 1 ) &times; S U ( 3 ) , is naturally derived, as well.

]]>Universe doi: 10.3390/universe4120149

Authors: Killian Martineau Aurélien Barrau

Emergent cosmological models, together with the Big Bang and bouncing scenarios, are among the possible descriptions of the early Universe. This work aims at clarifying some general features of the primordial tensor power spectrum in this specific framework. In particular, some naive beliefs are corrected. Using a toy model, we investigate the conditions required to produce a scale-invariant spectrum and show to what extent this spectrum can exhibit local features sensitive to the details of the scale factor evolution near the transition time.

]]>Universe doi: 10.3390/universe4120148

Authors: Mattia Dalla Brida

We present an overview of the recent lattice determination of the QCD coupling &alpha; s by the ALPHA Collaboration. The computation is based on the non-perturbative determination of the &Lambda;-parameter of Nf = 3 QCD, and the perturbative matching of the Nf = 3 and Nf = 5 theories. The final result: &alpha; s ( m Z ) = 0.11852 ( 84 ) , reaches sub-percent accuracy.

]]>Universe doi: 10.3390/universe4120147

Authors: Alessandro Di Marco Alexander Barabash Pierluigi Belli Rita Bernabei Roman Boiko Viktor Brudanin Fabio Cappella Vincenzo Caracciolo Riccardo Cerulli Dmitry Chernyak Fedor Danevich Antonella Incicchitti Dmytro Kasperovych Vladislav Kobychev Sergey Konovalov Matthias Laubenstein Vittorio Merlo Francesco Montecchia Oksana Polischuk Denys Poda Vladimir Shlegel Vladimir Tretyak Vladimir Umatov Yan Vasiliev Mykola Zarytskyy

Recent developments, results, and perspectives arising from double beta decay experiments at the Gran Sasso National Laboratory (LNGS) of the INFN by using HPGe detectors and crystal scintillators and by exploiting various approaches and different isotopes are summarized. The measurements here presented have been performed in the experimental set-ups of the DAMA collaboration. These setups are optimized for low-background studies and operate deep underground at LNGS. The presented results are of significant value to the field, and the sensitivity achieved for some of the considered isotopes is one of the best available to date.

]]>Universe doi: 10.3390/universe4120146

Authors: Mikhail Zubkov Zakhar Khaidukov Ruslan Abramchuk

Relativistic heavy ion collisions represent an arena for the probe of various anomalous transport effects. Those effects, in turn, reveal the correspondence between the solid state physics and the high energy physics, which share the common formalism of quantum field theory. It may be shown that for the wide range of field&ndash;theoretic models, the response of various nondissipative currents to the external gauge fields is determined by the momentum space topological invariants. Thus, the anomalous transport appears to be related to the investigation of momentum space topology&mdash;the approach developed earlier mainly in the condensed matter theory. Within this methodology we analyse systematically the anomalous transport phenomena, which include, in particular, the anomalous quantum Hall effect, the chiral separation effect, the chiral magnetic effect, the chiral vortical effect and the rotational Hall effect.

]]>Universe doi: 10.3390/universe4120145

Authors: Vadim Kolesnikov

The construction of the NICA accelerator facility is underway at Joint Institute for Nuclear Research (JINR) (Dubna, Russia). The main goal of the MPD experiment at NICA will be the experimental exploration of the Quantum Chromodynamics (QCD) phase structure at high baryon density. In this article, the current status of the NICA/MPD project is presented.

]]>Universe doi: 10.3390/universe4120144

Authors: George Livadiotis

Kappa distributions received impetus as they provide efficient modelling of the observed particle distributions in space and astrophysical plasmas throughout the heliosphere. This paper presents (i) the connection of kappa distributions with statistical mechanics, by maximizing the associated q-entropy under the constraints of the canonical ensemble within the framework of continuous description; (ii) the derivation of q-entropy from first principles that characterize space plasmas, the additivity of energy, and entropy; and (iii) the derivation of the characteristic first order differential equation, whose solution is the kappa distribution function.

]]>Universe doi: 10.3390/universe4120143

Authors: Alessandro Paoloni on Behalf of OPERA Collaboration

The OPERA experiment was designed to observe ν μ → ν τ oscillations through τ appearance on the CERN Neutrino to Gran Sasso (CNGS) beam over a baseline of 730 km. OPERA was a hybrid experiment composed of lead plates and emulsion layers acting as a target for neutrino interactions. The experiment was complemented with electronic detectors: scintillator strips used as Target Trackers and muon spectrometers. A review of the OPERA final results is presented in this paper.

]]>Universe doi: 10.3390/universe4120142

Authors: Herbert Weigel

We cautiously review the treatment of pentaquark exotic baryons in chiral soliton models. We consider two examples and argue that any consistent and self-contained description must go beyond the mean field approximation that only considers the classical soliton and the canonical quantization of its (would-be) zero modes via collective coordinates.

]]>Universe doi: 10.3390/universe4120141

Authors: Guo-Yuan Huang Zhi-Zhong Xing Jing-Yu Zhu

The latest global analysis of neutrino oscillation data indicates that the normal neutrino mass ordering is favored over the inverted one at the 3 &sigma; level. The best-fit values of the largest neutrino mixing angle &theta; 23 and the Dirac CP-violating phase &delta; are located in the higher octant and the third quadrant, respectively. We show that these experimental trends can be naturally explained by the &mu; - &tau; reflection symmetry breaking, triggered by the one-loop renormalization-group equations (RGEs) running from a superhigh energy scale down to the electroweak scale in the framework of the minimal supersymmetric standard model (MSSM). The complete parameter space is numerically explored for both the Majorana and Dirac cases, by allowing the smallest neutrino mass m 1 and the MSSM parameter tan &beta; to vary within their reasonable ranges.

]]>Universe doi: 10.3390/universe4120140

Authors: Breno L. Giacchini Tibério De Paula Netto

Local gravitational theories with more than four derivatives can have remarkable quantum properties. Namely, they can be super-renormalizable and may be unitary in the Lee-Wick sense, if the massive poles of the propagator are complex. It is important, therefore, to also explore the classical aspects of these theories. In this talk we present recent results in this direction. Specifically, we discuss the effect that that higher-order terms can have on the Newtonian potential and related singularities.

]]>Universe doi: 10.3390/universe4120139

Authors: Iarley P. Lobo Michele Ronco

Hypersurface deformation algebra consists of a fruitful approach to derive deformed solutions of general relativity based on symmetry considerations with quantum-gravity effects, of which the linearization has been recently demonstrated to be connected to the DSR program by &kappa; -Poincar&eacute; symmetry. Based on this approach, we analyzed the solution derived for the interior of a black hole and we found similarities with the so-called rainbow metrics, like a momentum-dependence of the metric functions. Moreover, we derived an effective, time-dependent Planck length and compared different regularization schemes.

]]>Universe doi: 10.3390/universe4120138

Authors: Viktor Abramov Olga Liivapuu Abdenacer Makhlouf

We propose the notion of ( q , &sigma; , &tau; ) -differential graded algebra, which generalizes the notions of ( &sigma; , &tau; ) -differential graded algebra and q-differential graded algebra. We construct two examples of ( q , &sigma; , &tau; ) -differential graded algebra, where the first one is constructed by means of the generalized Clifford algebra with two generators (reduced quantum plane), where we use a ( &sigma; , &tau; ) -twisted graded q-commutator. In order to construct the second example, we introduce the notion of ( &sigma; , &tau; ) -pre-cosimplicial algebra.

]]>Universe doi: 10.3390/universe4120137

Authors: Carlos Sabín

We consider the propagation of light along a 3D nanophotonic structure with the spatial shape of a spacetime containing a traversable wormhole. We show that waves experience significant changes of phase and group velocities when propagating along this curved space. This experiment can be realized with state-of-the-art nanophotonics technology.

]]>Universe doi: 10.3390/universe4120136

Authors: Fulvio Sbisà

We consider the 6D Cascading DGP model, a braneworld model which is a promising candidate to realize the phenomenon of the degravitation of vacuum energy. Focusing on a recently proposed thin limit description of the model, we study solutions where the induced metric on the codimension-2 brane is of the de Sitter form. While these solutions have already been recovered in the literature imposing by hand the bulk to be flat, we show that it is possible to derive them without making this assumption, by solving a suitably chosen subset of the bulk equations.

]]>Universe doi: 10.3390/universe4120135

Authors: Mikhail Zubkov

In the Painleve&ndash;Gullstrand (PG) reference frame, the description of elementary particles in the background of a black hole (BH) is similar to the description of non-relativistic matter falling toward the BH center. The velocity of the fall depends on the distance to the center, and it surpasses the speed of light inside the horizon. Another analogy to non-relativistic physics appears in the description of the massless fermionic particle. Its Hamiltonian inside the BH, when written in the PG reference frame, is identical to the Hamiltonian of the electronic quasiparticles in type II Weyl semimetals (WSII) that reside in the vicinity of a type II Weyl point. When these materials are in the equilibrium state, the type II Weyl point becomes the crossing point of the two pieces of the Fermi surface called Fermi pockets. It was previously stated that there should be a Fermi surface inside a black hole in equilibrium. In real materials, type II Weyl points come in pairs, and the descriptions of the quasiparticles in their vicinities are, to a certain extent, inverse. Namely, the directions of their velocities are opposite. In line with the mentioned analogy, we propose the hypothesis that inside the equilibrium BH there exist low-energy excitations moving toward the exterior of the BH. These excitations are able to escape from the BH, unlike ordinary matter that falls to its center. The important consequences to the quantum theory of black holes follow.

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