Search Results (55)

Constraining neutrino mass through cosmological observations relies on precise simulations to calibrate their effects on large scale structure, while these simulations must overcome computational challenges like dealing with large velocity dispersions and small intrinsic neutrino perturbations. We present an efficient N-body implementation with semi-linear neutrino mass response which gives accurate power spectra and halo statistics. We explore the necessity of correcting the expansion history caused by massive neutrinos and the transition between relativistic and non-relativistic components. The above method of including neutrino masses is built into the memory-, scalability-, and precision-optimized parallel N-body simulation code CUBE 2.0. Through a suite of neutrino simulations, we precisely quantify the neutrino mass effects on the nonlinear matter power spectra and halo statistics. Full article

Laboratory magnetoplasmas can become an intriguing experimental environment for fundamental studies relevant to nuclear astrophysics processes. Theoretical predictions indicate that the ionization state of isotopes within the plasma can significantly alter their lifetimes, potentially due to nuclear and atomic mechanisms such as bound-state β-decay. However, only limited experimental evidence on this phenomenon has been collected. PANDORA (Plasmas for Astrophysics, Nuclear Decay Observations, and Radiation for Archaeometry) is a novel facility which proposes to investigate nuclear decays in high-energy-density plasmas mimicking some properties of stellar nucleosynthesis sites (Big Bang Nucleosynthesis, s-process nucleosynthesis, role of CosmoChronometers, etc.). This paper focuses on the case of ⁷Be electron capture (EC) decay into ⁷Li, since its in-plasma decay rate has garnered considerable attention, particularly concerning the unresolved Cosmological Lithium Problem and solar neutrino physics. Numerical simulations were conducted to assess the feasibility of this possible lifetime measurement in the plasma of PANDORA. Both the ionization and atomic excitation of the ⁷Be isotopes in a He buffer Electron Cyclotron Resonance (ECR) plasma within PANDORA were explored via numerical modelling in a kind of “virtual experiment” providing the expected in-plasma EC decay rate. Since the decay of ⁷Be provides γ-rays at 477.6 keV from the ⁷Li excited state, Monte-Carlo GEANT4 simulations were performed to determine the γ-detection efficiency by the HPGe detectors array of the PANDORA setup. Finally, the sensitivity of the measurement was evaluated through a virtual experimental run, starting from the simulated plasma-dependent γ-rate maps. These results indicate that laboratory ECR plasmas in compact traps provide suitable environments for β-decay studies of ⁷Be, with the estimated duration of experimental runs required to reach 3σ significance level being few hours, which prospectively makes PANDORA a powerful tool to investigate the decay rate under different thermodynamic conditions and related charge state distributions. Full article

A new non-minimal version of the Einstein–Dirac-axion theory is established. This version of the non-minimal theory describing the interaction of gravitational, spinor, and axion fields is of the second order in derivatives in the context of the Effective Field Theory and is of the first order in the spinor particle number density. The model Lagrangian contains four parameters of non-minimal coupling and includes, in addition to the Riemann tensor, Ricci tensor, and Ricci scalar, as well as left-dual and right-dual curvature tensors. The pseudoscalar field appears in the Lagrangian in terms of trigonometric functions providing the discrete symmetry associated with axions, which is supported. The coupled system of extended master equations for the gravitational, spinor, and axion fields is derived; the structure of new non-minimal sources that appear in these master equations is discussed. Application of the established theory to the isotropic homogeneous cosmological model is considered; new exact solutions are presented for a few model sets of guiding non-minimal parameters. A special solution is presented, which describes an exponential growth of the spinor number density; this solution shows that spinor particles (massive fermions and massless neutrinos) can be born in the early Universe due to the non-minimal interaction with the spacetime curvature. Full article

Jets emanating from active galactic nuclei (AGNs) represent some of the most formidable particle accelerators in the universe, thereby emerging as viable candidates responsible for the detection of ultra-high-energy cosmic rays (UHECRs). If AGN jets indeed serve as origins of UHECRs, then the diffuse flux of these cosmic rays would be dependent on the power and duty cycle of these jets, which are inherently connected to the nature of black hole accretion flows. In this article, we present our cosmological semi-analytic framework, JET (Jets from Early Times), designed to trace the evolution of jetted AGN populations. This framework serves as a valuable tool for predictive analyses of cosmic ray energy density and, potentially, neutrino energy density. By using JET, we model the formation and evolution of galaxies and supermassive black holes (SMBHs) from $z=20$ to $z=1$, incorporating jet formation and feedback mechanisms and distinguishing between various accretion states determined by the SMBH Eddington ratios. The implications of different SMBH growth models on predicting cosmic ray flux are investigated. We provide illustrative examples demonstrating how the associated diffuse UHECR fluxes at the source may vary in relation to the jet production efficiencies and the selected SMBH growth model, linking cosmological models of SMBH growth with astroparticle backgrounds. Full article

The cosmological lepton asymmetry, i.e., an excess of leptons over antileptons, is still only loosely constrained, and might be much larger than its tiny baryonic counterpart. If this is the case, charge neutrality requires the lepton asymmetries to be confined in the neutrino sector. We recall the observational effects of neutrino asymmetries on the abundance of light elements produced during Big Bang Nucleosynthesis and on the pattern of cosmic microwave background anisotropies. We point to the necessity of solving the neutrino transport equations, taking into account the effect of flavour oscillation, to derive general and robust constraints on lepton asymmetries. We review the current bounds and briefly discuss prospects for next-generation CMB experiments. Full article

Focusing on elastic neutrino–electron scattering events, we explore the prospect of constraining new physics beyond the Standard Model at the DUNE Near Detector (ND). Specifically, we extract the attainable sensitivities for motivated scenarios such as neutrino generalized interactions (NGIs), the sterile neutrino dipole portal and unitarity violation. We furthermore examine the impact of the $\tau$-optimized flux at the DUNE-ND and compare our results with those obtained using the standard CP-optimized flux. We find that our present analysis is probing a previously unexplored region of the parameter space, complementing existing results from cosmological observations and terrestrial experiments. Full article

In the framework of quantum field theory, we analyze the neutrino oscillations in the presence of a torsion background. We consider the Einstein–Cartan theory and we study the cases of constant torsion and of linearly time-dependent torsion. We derive new neutrino oscillation formulae which depend on the spin orientation. Indeed, the energy splitting induced by the torsion influences oscillation amplitudes and frequencies. This effect is maximal for values of torsion of the same order of the neutrino masses and for very low momenta, and disappears for large values of torsion. Moreover, neutrino oscillation is inhibited for intensities of torsion term much larger than neutrino masses and momentum. The modifications induced by torsion on the $CP$-asymmetry are also presented. Future experiments, such as PTOLEMY, which have as a goal the analysis of the cosmological background of neutrino (which have very low momenta), can provide insights into the effect shown here. Full article

At least two relics of the Big Bang have survived: the cosmological microwave background (CMB) and the cosmological neutrino background (C$\nu$B). Being the second most abundant particle in the universe, the neutrino has a significant impact on its evolution from the Big Bang to the present day. Neutrinos affect the following cosmological processes: the expansion rate of the universe, its chemical and isotopic composition, the CMB anisotropy and the formation of the large-scale structure of the universe. Another relic neutrino background is theoretically predicted, it consists of non-equilibrium antineutrinos of Primordial Nucleosynthesis arising as a result of the decay of neutrons and tritium nuclei. Such antineutrinos are an indicator of the baryon asymmetry of the universe. In addition to experimentally detectable active neutrinos, the existence of sterile neutrinos is theoretically predicted to generate neutrino masses and explain their oscillations. Sterile neutrinos can also solve such cosmological problems as the baryonic asymmetry of the universe and the nature of dark matter. The recent results of several independent experiments point to the possibility of the existence of a light sterile neutrino. However, the existence of such a neutrino is inconsistent with the predictions of the Standard Cosmological Model. The inclusion of a non-zero lepton asymmetry of the universe and/or increasing the energy density of active neutrinos can eliminate these contradictions and reconcile the possible existence of sterile neutrinos with Primordial Nucleosynthesis, the CMB anisotropy, and also reduce the H₀-tension. In this brief review, we discuss the influence of the physical properties of active and sterile neutrinos on the evolution of the universe from the Big Bang to the present day. Full article

I consider the electro-weak (EW) masses and interactions generated by photons using vacuum expectation values of Stueckelberg and Higgs fields. I provide a prescription to relate their parametric values to a cosmological range derived from the fundamental Heisenberg uncertainty principle and the Einstein–de Sitter cosmological constant and horizon. This yields qualitative connections between microscopic ranges acquired by $W^{\pm }$ or $Z^0$ gauge Bosons and the cosmological scale and minimal mass acquired by g-photons. I apply this procedure to an established Stueckelberg–Higgs mechanism, while I consider a similar procedure for a pair of Higgs fields that may spontaneously break all U(1) × SU(2) gauge invariances. My estimates of photon masses and their additional parity-breaking interactions with leptons and neutrinos may be detectable in suitable accelerator experiments. Their effects may also be observable astronomically through massive g-photon condensates that may contribute to dark matter and dark energy. Full article

We use Big Bang Nucleosynthesis (BBN) to probe Beyond Standard Model physics in the neutrino sector. Recently, the abundances of primordially produced light elements D and He-4 were determined from observations with better accuracy. The good agreement between the theoretically predicted abundances of primordially produced light elements and those derived from observations allows us to update the BBN constraints on Beyond Standard Model (BSM) physics. We provide numerical analysis of several BSM models of BBN and obtain precise cosmological constraints and indications for new neutrino physics. Namely, we derive more stringent BBN constraints on electron neutrino–sterile neutrino oscillations corresponding to $1\%$ uncertainty of the observational determination of the primordial He-4. The cosmological constraints are obtained both for the zero and non-zero cases of the initial population of the sterile neutrino state. Then, in a degenerate BBN model with neutrino ${\nu }_e\leftrightarrow {\nu }_s$ oscillations, we analyze the change in the cosmological constraints in case lepton asymmetry L is big enough to suppress oscillations. We obtain constraints on the lepton asymmetry L. We discuss a possible solution to the dark radiation problem in degenerate BBN models with ${\nu }_e\leftrightarrow {\nu }_s$ oscillations in case L is large enough to suppress neutrino oscillations during the BBN epoch. Interestingly, the required value of L for solving the DR problem is close to the value of L indicated by the EMPRESS experiment, and also it is close to the value of lepton asymmetry that is necessary to relax Hubble tension. Full article

The matter fluctuation parameter ${\sigma }_8$ is, by model construction, degenerate with the growth index $\gamma$. Here, we study the effect on the cosmological parameter constraints by treating each independently from one another, considering ${\sigma }_8$ as a free and non-derived parameter along with a free $\gamma$. We then try to constrain all parameters using three probes that span from deep to local redshifts, namely the CMB spectrum, the growth measurements from redshift space distortions $f{\sigma }_8$, and the galaxy cluster counts. We also aim to assess the impact of this relaxation on the ${\sigma }_8$ tension between its inferred CMB value in comparison to that obtained from local cluster counts. We also propose a more sophisticated correction, along with the classical one, that takes into account the impact of cosmology on the growth measurements when the parameters are varied in the Monte Carlo process, which consist in adjusting the growth to keep the observed power spectrum, integrated over all angles and scales, as invariant with the background evolution. We found by using the classical correction that untying the two parameters does not shift the maximum likelihood of either ${\sigma }_8$ or $\gamma$, but it rather enables larger bounds with respect to when ${\sigma }_8$ is a derived parameter, and that when considering CMB + $f{\sigma }_8$, or when further combining with cluster counts albeit with tighter bounds. Precisely, we obtain ${\sigma }_8=0.809\pm 0.043$ and $\gamma =0.613\pm 0.046$ in agreement with Planck’s constraint for the former and compatible with ΛCDM for the latter but with bounds wide enough to accommodate both values subject to the tensions. Allowing for massive neutrinos does not change the situation much. On the other hand, considering a tiered correction yields ${\sigma }_8=0.734\pm 0.013$ close to ∼1 $\sigma$ for the inferred local values albeit with a growth index of $\gamma =0.636\pm 0.022$ at ∼2 $\sigma$ from its ΛCDM value. Allowing for massive neutrinos in this case yielded ${\sigma }_8=0.756\pm 0.024$, still preferring low values but with much looser constraints on $\gamma =0.549\pm 0.048$ and a slight preference for $\mathsf{\Sigma }{m}_{\nu }\sim 0.19$. We conclude that untying ${\sigma }_8$ and $\gamma$ helps in relieving the discomfort on the former between the CMB and local probes, and that careful analysis should be followed when using data products treated in a model-dependent way. Full article

We offer a survey of the matter-antimatter evolution within the primordial Universe. While the origin of the tiny matter-antimatter asymmetry has remained one of the big questions in modern cosmology, antimatter itself has played a large role for much of the Universe’s early history. In our study of the evolution of the Universe we adopt the position of the standard model Lambda-CDM Universe implementing the known baryonic asymmetry. We present the composition of the Universe across its temperature history while emphasizing the epochs where antimatter content is essential to our understanding. Special topics we address include the heavy quarks in quark-gluon plasma (QGP), the creation of matter from QGP, the free-streaming of the neutrinos, the vanishing of the muons, the magnetism in the electron-positron cosmos, and a better understanding of the environment of the Big Bang Nucleosynthesis (BBN) producing the light elements. We suggest but do not explore further that the methods used in exploring the early Universe may also provide new insights in the study of exotic stellar cores, magnetars, as well as gamma-ray burst (GRB) events. We describe future investigations required in pushing known physics to its extremes in the unique laboratory of the matter-antimatter early Universe. Full article

Upcoming LIGO–Virgo–KAGRA (LVK) observational runs offer new opportunities to probe the central engines of extreme transient events. Cosmological gamma-ray bursts (GRBs) and core-collapse supernovae (CC-SNe), in particular, are believed to be powered by compact objects, i.e., a neutron star (NS) or black hole (BH). A principal distinction between an NS and BH is the energy reservoir in the angular momentum $E_J$. Per unit mass, this reaches a few percent in a rapidly rotating NS and tens of percent in a Kerr BH, respectively. Calorimetry by ${\mathcal{E}}_{GW}$ on a descending chirp may break the degeneracy between the two. We review this approach, anticipating new observational opportunities for planned LVK runs. GRB170817A is the first event revealing its central engine by a descending chirp in gravitational radiation. An accompanying energy output ${\mathcal{E}}_{GW}\simeq 3.5\%M_{\odot }{c}^2$ is observed during GRB170817A in the aftermath of the double neutron star merger GW170817. The progenitors of normal long GRBs, on the other hand, are the rare offspring of CC-SNe of type Ib/c. Yet, the extended emission to SGRBs (SGRBEEs) shares similar durations and the same Amati-relation of the prompt GRB emission of LGRBs, pointing to a common central engine. The central engine of these extreme transient events has, hitherto, eluded EM observations alone, even when including neutrino observations, as in SN1987A. The trigger signaling the birth of the compact object and the evolution powering these events is expected to be revealed by an accompanying GW signal, perhaps similar to that of GRB170817A. For GRB170817A, ${\mathcal{E}}_{GW}$ exceeds $E_J$ in the initial hyper-massive neutron star (HMNS) produced in the immediate aftermath of GW170817. It identifies the spin-down of a Kerr BH of mass ∼$2.4M_{\odot }$ defined by the total mass of GW170817. This observation is realized in spectrograms generated by Butterfly matched filtering, a time-symmetric analysis with equal sensitivity to ascending and descending chirps, calibrated by signal injection experiments. It is implemented on a heterogeneous computing platform with synaptic parallel processing in F90/C++/C99 under bash. A statistical significance of $5.5\sigma$ is derived from multi-messenger event timing, based on a probability of false alarm (PFA) factored over a probability $p_1=8.3\times {10}^{-4}$ by causality and a p-value $p_2=4.9\times {10}^{-5}$ of consistency between H1 and L1 observations. For upcoming observations, this approach may be applied to similar emissions from SNIb/c and GRBs in the Local Universe, upon the mass-scaling of present results by the mass of their putative black hole-central engines. Full article

The neutrino is perhaps the most elusive member of the particle zoo. The questions about its nature, namely: Dirac or Majorana, the value of its mass and the interactions with other particles, the number of its components including sterile species, are long standing ones and still remain to a large extent without conclusive answers. From the side of the nuclear structure and nuclear reactions, both theories and experiments, the need to elucidate these questions has, and still has, prompt crucial developments in the fields of double beta decay, double charge exchange and neutrino induced reactions. The measurements of neutrino flavor oscillation parameters contribute largely to restrict models with massless neutrinos. From the particle physics side, the possibilities to extend the standard model of electroweak interactions to incorporate a right-handed sector of the electroweak Lagrangian are directly linked to the adopted neutrino model. Here, I would like to address another aspect of the problem by asking the question of the neutrino mass mechanism in the cosmological context, and particularly about dark matter. Full article

The study of massive neutrinos and their interactions is a critical aspect of contemporary cosmology. Recent advances in parallel computation and high-performance computing provide new opportunities for accurately constraining Large-Scale Structures (LSS). In this paper, we introduce the TianNu cosmological N-body simulation during the co-evolution of massive neutrino and cold dark matter components via the CUBEP${}^3$M code running on the supercomputer Tianhe-2 and TianNu’s connected works. We start by analyzing $2.537\times {10}^7$ dark halos from the scientific data of TianNu simulation, and compare their angular momentum with the matched halos from neutrino-free TianZero, revealing a dependence of angular momentum modulus on neutrino injection at scales below 50 Mpc and around 10 Mpc. Full article