Search Results (51)

The contraction method is a procedure that allows to establish non-trivial relations between Lie algebras and has had successful applications in both mathematics and theoretical physics. This work deals with generalizations of the contraction procedure, with a main focus on the so-called S-expansion method, as it includes most of the other generalized contractions. Basically, the S-expansion combines a Lie algebra $\mathcal{G}$ with a finite abelian semigroup S in order to define new S-expanded algebras. After giving a description of the main ingredients used in this paper, we present a Java library that automates the S-expansion procedure. With this computational tool, we are able to represent Lie algebras and semigroups, so we can perform S-expansions of Lie algebras using arbitrary semigroups. We explain how the library methods have been constructed and how they work; then, we give a set of example programs aimed to solve different problems. They are presented so that any user can easily modify them to perform their own calculations, without necessarily being an expert in Java. Finally, some comments about further developments and possible new applications are made. Full article

The temperature and polarization anisotropies of the cosmic microwave background (CMB) as measured today can offer key insights into the topology of the early universe prior to inflation, for example by discriminating between flat and warped geometries. In this paper, we focus on a Kaluza–Klein model with an extra spatial dimension that compactifies at the Grand Unified Theory (GUT) epoch, subject to mixed Neumann/Dirichlet boundary conditions at fixed points. As a consequence, a set of Infrared (IR) cutoffs emerges in both the scalar and tensor spectra, leading to observable consequences in the CMB. We examine the possible signatures of such a topology in detail, particularly in relation to the even–odd parity imbalance already reported by the COBE, WMAP and Planck missions in the temperature angular correlations. Furthermore, we extend our analysis to the existing Planck E-mode polarization data and to the high-precision B-mode polarization measurements expected from the forthcoming LiteBIRD mission. Full article

Future $e^{+}{e}^{-}$ colliders are expected to play a fundamental role in measuring Standard Model (SM) parameters with unprecedented precision and in probing physics beyond the SM (BSM). This study investigates two-particle angular correlation distributions involving final-state SM charged hadrons. Unexpected correlation structures in these distributions is considered to be a hint for new physics perturbing the QCD partonic cascade and thereby modifying azimuthal and (pseudo)rapidity correlations. Using Pythia8 Monte Carlo generator and fast simulation, including selection cuts and detector effects, we study potential structures in the two-particle angular correlation function. We adopt the QCD-like Hidden Valley (HV) scenario as implemented in Pythia8 generator, with relatively light HV v-quarks (below about 100 GeV), to illustrate the potential of this method. Full article

The polynomial affine model of gravity was proposed as an alternative to metric and metric-affine gravitational models. What, in the beginning, was thought to be a source of unpredictability—the presence of many terms in the action—turned out to be a milestone since it contains all possible combinations of the fields compatible with the covariance under diffeomorphisms. Here, we present a review of the advances in the analysis of the model after 10 years of its proposal and sketch the guidelines for our future perspectives. Full article

A ready-to-use spectrometer-based product, which focuses on data acquisition using a BeagleBone board and a Hamamatsu C12666MA spectrometer module, is presented. The device meets stringent requirements, including the ability to measure the visible light spectrum over a wide range of intensities, being compact and lightweight, and having customizable electronics to suit different application needs. The system’s primary component is a Hamamatsu C12666MA spectrometer module with a measurement range of 341 nm to 780 nm, which is supplemented by supporting electronics such as a microcontroller and an analog-to-digital converter. The development encompasses hardware design, the fabrication of a control board, and software development for spectral acquisition and visualization. The software controls the spectral measurement process and facilitates data processing and analysis. The results demonstrate that the designed system can accurately capture spectra and fulfill the specified requirements. Additionally, this work investigates and evaluates the potential migration of the data acquisition system to Field-Programmable Gate Array technology. Such a migration offers several advantages, including real-time processing, parallel data handling capabilities, reduced latency, and greater flexibility in adapting to various spectrometer configurations, as well as the possibility to work in a synchronized way with other devices. These improvements would significantly expand the system’s potential applications in real-time spectroscopy and other demanding optical measurement tasks. The proposed system thus provides a foundation for future enhancements, which could exploit Field-Programmable Gate Array technology, potentially revolutionizing the efficiency and application scope of portable spectrometry devices. Full article

Underwater acoustic (UWA) communication encounters significant challenges, including impulsive noise from breaking waves and marine organisms, as well as long-delay taps caused by ocean properties and high transmission rates. To address these issues, we enhance the channel estimation process by introducing iteratively reweighted least squares (IRLS) methods and propose an impulsive noise suppression algorithm. Furthermore, we analyze the inter-frequency interference (IFI) resulting from channel variability and implement IFI cancellation (IFIC) during iterative processing. Furthermore, an IFIC-based dual decision–feedback equalization (DDFE) algorithm is proposed for fast time-varying channels, enabling a considerable reduction in channel length and subsequent equalizer complexity. The proposed IFIC-based DDFE algorithm with impulsive noise suppression has been validated through sea trial data, demonstrating robustness against impulsive noise. Experimental results indicate that the proposed algorithm reduces click signal energy and significantly improves receiver performance compared to traditional DDFE algorithms. This research highlights the effectiveness of adapted UWA communication strategies in environments characterized by impulsive noise and long delay taps, facilitating more reliable UWA communication. Full article

A fundamental aspect in the evolution of Time-to-Digital Converters (TDCs) implemented within Field-Programmable Gate Arrays (FPGAs), given the increasing demand for detection channels, is the optimization of resource utilization. This study reviews the principal methodologies employed for implementing low-resource TDCs in FPGAs. It outlines the foundational architectures and interpolation techniques utilized to bolster TDC performances without unduly burdening resource consumption. Low-resource Tapped Delay Line, Vernier Ring Oscillator, and Multi-Phase Shift Counter TDCs, including the use of SerDes, are reviewed. Additionally, novel low-resource architectures are scrutinized, including Counter Gray Oscillator TDCs and interpolation expansions using Process–Voltage–Temperature stable IODELAYs. Furthermore, the advantages and limitations of each approach are critically assessed, with particular emphasis on resolution, precision, non-linearities, and especially resource utilization. A comprehensive summary table encapsulating existing works on low-resource TDCs is provided, offering a comprehensive overview of the advancements in the field. Full article

We study the space-time geometry generated by coupling a free scalar field with a noncanonical kinetic term to general relativity in $(2+1)$ dimensions. After identifying a family of scalar Lagrangians that yield exact analytical solutions in static and circularly symmetric scenarios, we classify the various types of solutions and focus on a branch that yields asymptotically flat geometries. We show that the solutions within such a branch can be divided in two types, namely naked singularities and nonsingular objects without a center. In the latter, the energy density is localized around a maximum and vanishes only at infinity and at an inner boundary. This boundary has vanishing curvatures and cannot be reached by any time-like or null geodesic in finite affine time. This allows us to consistently interpret such solutions as nonsingular, lump-like, static compact scalar objects whose eventual extension to the $(3+1)$-dimensional context could provide structures of astrophysical interest. Full article

The KM3NeT Collaboration is building an underwater neutrino observatory at the bottom of the Mediterranean Sea, consisting of two neutrino telescopes, both composed of a three-dimensional array of light detectors, known as digital optical modules. Each digital optical module contains a set of 31 three-inch photomultiplier tubes distributed over the surface of a 0.44 m diameter pressure-resistant glass sphere. The module also includes calibration instruments and electronics for power, readout, and data acquisition. The power board was developed to supply power to all the elements of the digital optical module. The design of the power board began in 2013, and ten prototypes were produced and tested. After an exhaustive validation process in various laboratories within the KM3NeT Collaboration, a mass production batch began, resulting in the construction of over 1200 power boards so far. These boards were integrated in the digital optical modules that have already been produced and deployed, which total 828 as of October 2023. In 2017, an upgrade of the power board, to increase reliability and efficiency, was initiated. The validation of a pre-production series has been completed, and a production batch of 800 upgraded boards is currently underway. This paper describes the design, architecture, upgrade, validation, and production of the power board, including the reliability studies and tests conducted to ensure safe operation at the bottom of the Mediterranean Sea throughout the observatory’s lifespan. Full article

Silicon Photomultipliers find applications across various fields. One potential Silicon Photomultiplier application domain is neutrino telescopes, where they may enhance the angular resolution. However, the elevated dark count rate associated with Silicon Photomultipliers represents a significant challenge to their widespread utilization. To address this issue, it is proposed to use Silicon Photomultipliers and Photomultiplier Tubes together. The Photomultiplier Tube signals serve as a trigger to mitigate the dark count rate, thereby preventing undue saturation of the available bandwidth. This paper presents an investigation into a fast and resource-efficient method for filtering the Silicon Photomultiplier dark count rate. A low-resource and fast coincident filter has been developed, which removes the Silicon Photomultiplier dark count rate by using as a trigger the Photomultiplier Tube input signals. The architecture of the coincidence filter, together with the first results obtained, which validate the effectiveness of this method, is presented. Full article

The Unruh vacuum is widely used as a quantum state to describe black hole evaporation since, near the horizon, it reproduces the physical state of a quantum field, the so-called “in-vacuum”, in the case where a black hole is formed by gravitational collapse. We examine the relation between these two quantum states in the background spacetime of a Reissner–Nordström black hole (both extremal and not), highlighting the similarities and striking differences. Full article

Expert groups recommend that populations adopt dietary patterns higher in whole, plant-based foods and lower in red and processed meat as a high-impact climate action. Yet, there is limited understanding of populations’ willingness to adopt plant-rich dietary patterns. This study examined United States (US) adults’ perceptions, beliefs, and behaviors towards plant-rich dietary patterns and practices over a decade. Fifteen questions from the International Food Information Council’s Food and Health Surveys (2012–2022) were analyzed across four sustainability domains (i.e., human health, environmental, social, and economic domains). Most respondents had favorable perceptions of environmentally sustainable food and beverages, but sustainability influenced less than half of consumers’ purchase decisions. Plant-rich dietary pattern adherence increased across survey years (12.1% [2019] to 25.8% [2022], p < 0.001). One-quarter (28.1%) of Americans reported reducing their red meat intake over 12 months (2020–2022). Yet, another 15.5% reported greater red meat intake, and 18.8% reported greater plant-based meat alternative (PBMA) intake over 12 months. The percentage of respondents who reported greater red meat and PBMA consumption in the previous 12 months significantly increased across the years surveyed (2020–2022, p < 0.05). IFIC Survey findings highlight growing US consumer awareness of health, environmental, and social sustainability but low adoption of plant-rich dietary patterns and practices. Government leadership and coordinated actions by health professionals, civil society, and businesses are needed to educate and incentivize Americans to adopt plant-rich dietary behaviors, and greater industry transparency is needed to show how food and beverage products support human and planetary health. Full article

In this paper, the formulation of Quantum Mechanics in terms of fuzzy logic and fuzzy sets is explored. A result by Pykacz, which establishes a correspondence between (quantum) logics (lattices with certain properties) and certain families of fuzzy sets, is applied to the Birkhoff–von Neumann logic, the lattice of projectors of a Hilbert space. Three cases are considered: the qubit, two qubits entangled, and a qutrit ‘nested’ inside the two entangled qubits. The membership functions of the fuzzy sets are explicitly computed and all the connectives of the fuzzy sets are interpreted as operations with these particular membership functions. In this way, a complete picture of the standard quantum logic in terms of fuzzy sets is obtained for the systems considered. Full article

We analyze the correlations functions across the horizon in Hawking black hole radiation to reveal the correlations between Hawking particles and their partners. The effects of the underlying space–time on this are shown in various examples ranging from acoustic black holes to regular black holes. Full article

This paper encapsulates details of the NEMO laser beacon’s design, offering a profound contribution to the field of the time calibration of underwater neutrino telescopes. The mechanical design of the laser beacon, which operates at a depth of 3500 m, is presented, together with the design of the antibiofouling system employed to endure the operational pressure and optimize the operational range, enhancing its functionality and enabling time calibration among multiple towers. A noteworthy innovation central to this development lies in the battery system. This configuration enhances the device’s portability, a crucial aspect in underwater operations. The comprehensive design of the laser beacon, encompassing the container housing, the requisite battery system for operation, electronics, and an effective antibiofouling system, is described in this paper. Additionally, this paper presents the findings of the laser beacon’s qualification process. Full article