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Volume 5
Issue 2
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Particles, Volume 5, Issue 2 (June 2022) – 10 articles

Cover Story (view full-size image): New Jefferson Lab data allow us to extract QCD effective coupling as over a large range of distances. In the plot, distance is essentially inverse to the energy-momentum Q, with large distances on the left and short distances on the right. The data show that as freezes, i.e., loses its Q-dependence, at large distances (low Q). The freezing, crucial for the use of gauge/gravity duality to study QCD, breaks down when transitioning from the QCD effective degrees of freedom (hadrons) to the fundamental ones (quarks and gluons). This transition, revealed by the drastic variation of as, occurs at a scale indicative of chiral symmetry breaking. The breaking of chiral symmetry at low Q, one of the crucial properties of QCD, is believed to cause the emergence of the global properties of hadrons. View this paper
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12 pages, 1090 KiB  
Article
Stripping Model for Short Gamma-Ray Bursts in Neutron Star Mergers
by Sergei Blinnikov, Andrey Yudin, Nikita Kramarev and Marat Potashov
Particles 2022, 5(2), 198-209; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020018 - 16 Jun 2022
Cited by 7 | Viewed by 1919
Abstract
We overview the current status of the stripping model for short gamma-ray bursts. After the historical joint detection of the gravitational wave event GW170817 and the accompanying gamma-ray burst GRB170817A, the relation between short gamma-ray bursts and neutron star mergers has been reliably [...] Read more.
We overview the current status of the stripping model for short gamma-ray bursts. After the historical joint detection of the gravitational wave event GW170817 and the accompanying gamma-ray burst GRB170817A, the relation between short gamma-ray bursts and neutron star mergers has been reliably confirmed. Many properties of GRB170817A, which turned out to be peculiar in comparison with other short gamma-ray bursts, are naturally explained in the stripping model, suggested by one of us in 1984. We point out the role of late Dmitriy Nadyozhin (1937–2020) in predicting the GRB and kilonova properties in 1990. We also review the problems to be solved in the context of this model. Full article
(This article belongs to the Special Issue Selected Papers from “The Modern Physics of Compact Stars and Relativistic Gravity 2021”)
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10 pages, 1754 KiB  
Article
Approaches to Measuring Direct Photon Yield in A–A Collisions
by Dmitri Peresunko
Particles 2022, 5(2), 188-197; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020017 - 09 Jun 2022
Viewed by 1443
Abstract
An overview of experimental methods for measuring direct photon spectra in pp, p–A and A–A collisions is presented. The advantages and limitations of each method are discussed and illustrated by the results of various experiments. Full article
(This article belongs to the Special Issue Selected Papers from "Physics Performance Studies at FAIR and NICA")
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8 pages, 2882 KiB  
Article
Diurnal Variations of the Count Rates from Dark Photons in PHELEX
by Anatoly Kopylov, Igor Orekhov and Valery Petukhov
Particles 2022, 5(2), 180-187; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020016 - 06 Jun 2022
Cited by 3 | Viewed by 1400
Abstract
This paper reports the PHELEX experiment, i.e., PHoton–ELectron EXperiment, to search for the dark photons (DPs) of cold dark matter using a multicathode counter technique specifically developed for this purpose by the authors. The paper presents new data, a novel upper limit for [...] Read more.
This paper reports the PHELEX experiment, i.e., PHoton–ELectron EXperiment, to search for the dark photons (DPs) of cold dark matter using a multicathode counter technique specifically developed for this purpose by the authors. The paper presents new data, a novel upper limit for the constant of kinetic mixing, and the first results of measurements of the diurnal variations in solar and stellar frames. The perspectives of this method are outlined in terms of the search for DPs. Full article
(This article belongs to the Collection Dark Matter and New Physics of Hidden Particles)
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9 pages, 357 KiB  
Article
Experimental Determination of the QCD Effective Charge αg1(Q)
by Alexandre Deur, Volker Burkert, Jian-Ping Chen and Wolfgang Korsch
Particles 2022, 5(2), 171-179; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020015 - 31 May 2022
Cited by 15 | Viewed by 8060
Abstract
The QCD effective charge αg1(Q) is an observable that characterizes the magnitude of the strong interaction. At high momentum Q, it coincides with the QCD running coupling αs(Q). At low Q, [...] Read more.
The QCD effective charge αg1(Q) is an observable that characterizes the magnitude of the strong interaction. At high momentum Q, it coincides with the QCD running coupling αs(Q). At low Q, it offers a nonperturbative definition of the running coupling. We have extracted αg1(Q) from measurements carried out at Jefferson Lab that span the very low to moderately high Q domain, 0.14≤Q≤2.18 GeV. The precision of the new results is much improved over the previous extractions and the reach in Q at the lower end is significantly expanded. The data show that αg1(Q) becomes Q-independent at very low Q. They compare well with two recent predictions of the QCD effective charge based on Dyson–Schwinger equations and on the AdS/CFT duality. Full article
(This article belongs to the Special Issue Strong Interactions in the Standard Model: Massless Bosons to Compact Stars)
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0 pages, 1768 KiB  
Article
Unruh Effect and Information Entropy Approach
by Maksym Teslyk, Larissa Bravina and Evgeny Zabrodin
Particles 2022, 5(2), 157-170; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020014 - 27 May 2022
Cited by 2 | Viewed by 2577 | Correction
Abstract
The Unruh effect can be considered a source of particle production. The idea has been widely employed in order to explain multiparticle production in hadronic and heavy-ion collisions at ultrarelativistic energies. The attractive feature of the application of the Unruh effect as a [...] Read more.
The Unruh effect can be considered a source of particle production. The idea has been widely employed in order to explain multiparticle production in hadronic and heavy-ion collisions at ultrarelativistic energies. The attractive feature of the application of the Unruh effect as a possible mechanism of the multiparticle production is the thermalized spectra of newly produced particles. In the present paper, the total entropy generated by the Unruh effect is calculated within the framework of information theory. In contrast to previous studies, here the calculations are conducted for the finite time of existence of the non-inertial reference frame. In this case, only a finite number of particles are produced. The dependence on the mass of the emitted particles is taken into account. Analytic expression for the entropy of radiated boson and fermion spectra is derived. We study also its asymptotics corresponding to low- and high-acceleration limiting cases. The obtained results can be further generalized to other intrinsic degrees of freedom of the emitted particles, such as spin and electric charge. Full article
(This article belongs to the Collection High Energy Physics)
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11 pages, 1925 KiB  
Article
The Novel Scaling of Tsallis Parameters from the Transverse Momentum Spectra of Charged Particles in Heavy-Ion Collisions
by Junqi Tao, Weihao Wu, Meng Wang, Hua Zheng, Wenchao Zhang, Lilin Zhu and Aldo Bonasera
Particles 2022, 5(2), 146-156; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020013 - 09 May 2022
Cited by 6 | Viewed by 2120
Abstract
The transverse momentum (pT) spectra of charged particles measured in Au + Au collisions from the beam energy scan (BES) program, Cu + Cu collisions at sNN=62.4, 200 GeV at the RHIC and Pb + [...] Read more.
The transverse momentum (pT) spectra of charged particles measured in Au + Au collisions from the beam energy scan (BES) program, Cu + Cu collisions at sNN=62.4, 200 GeV at the RHIC and Pb + Pb, Xe + Xe collisions at the LHC are investigated in the framework of Tsallis thermodynamics. The theory can describe the experimental data well for all the collision systems, energies and centralities investigated. The collision energy and centrality dependence of the Tsallis distribution parameters, i.e., the temperature T and the nonextensive parameter q, for the A + A collisions are also studied and discussed. A novel scaling between the temperature divided by the natural logarithm of collision energy (T/lns) and the nonextensive parameter q is presented. Full article
(This article belongs to the Collection High Energy Physics)
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11 pages, 1611 KiB  
Article
Rabi Frequency Management of Collapsing Quasi-Two-Dimensional Bose-Einstein Condensates with Pseudospin-1/2
by Shukhrat N. Mardonov and Bobomurat J. Ahmedov
Particles 2022, 5(2), 135-145; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020012 - 28 Apr 2022
Viewed by 1739
Abstract
The collapse of quasi-two-dimensional pseudospin-1/2 Bose-Einstein condensate of attracting atoms with intra- and cross-spin interaction is studied in the presence of the Rabi coupling. The condensate dynamics is presented as a function of the self-interaction and Rabi frequency. The evolution of two components [...] Read more.
The collapse of quasi-two-dimensional pseudospin-1/2 Bose-Einstein condensate of attracting atoms with intra- and cross-spin interaction is studied in the presence of the Rabi coupling. The condensate dynamics is presented as a function of the self-interaction and Rabi frequency. The evolution of two components of the condensate by using the Gross-Pitaevskii equations is investigated. The initial Gaussian ansatz for two-component wave functions is selected for the better interpretation of the numerical results. The intra-spin-coupling modifies the critical number of atoms causing the collapse while the collapse is observed only in a single pseudospin component. It is demonstrated that for cross-spin-coupling only double spin-components collapse can occur. Full article
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7 pages, 1161 KiB  
Article
Effect of Protoneutron Star Magnetized Envelops in Neutrino Energy Spectra
by Vladimir N. Kondratyev, Tamara D. Lobanovskaya and Dimash B. Torekhan
Particles 2022, 5(2), 128-134; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020011 - 12 Apr 2022
Cited by 5 | Viewed by 1805
Abstract
The neutrino dynamics in hot and dense magnetized matter, which corresponds with protoneutron star envelopes in the core collapse supernova explosions, is considered. The kinetic equation for a neutrino phase space distribution function is obtained, taking into account inelastic scattering by nuclear particles. [...] Read more.
The neutrino dynamics in hot and dense magnetized matter, which corresponds with protoneutron star envelopes in the core collapse supernova explosions, is considered. The kinetic equation for a neutrino phase space distribution function is obtained, taking into account inelastic scattering by nuclear particles. The transfer component in a momentum space using transport properties is studied. The energy transfer coefficient is shown to change from positive to negative values when the neutrino energy exceeds four times the matter temperature. In the vicinity of a neutrino sphere, such effects are illustrated to lead to the energy strengthening in the neutrino spectra. As this paper demonstrates, such a property is favorable for the possibility of observing supernova neutrino fluxes using Large Volume Neutrino Telescopes. Full article
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18 pages, 3612 KiB  
Article
Electrostatic Simulations for the DUNE ND-GAr Field Cage
by Christopher Hayes and Jon Urheim
Particles 2022, 5(2), 110-127; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020010 - 06 Apr 2022
Viewed by 2064
Abstract
ND-GAr is one of three detector systems in the design of the DUNE Near Detector complex, which will be located on the Fermilab campus, sixty meters underground and 570 m from the source of an intense neutrino beam. ND-GAr will consist of a [...] Read more.
ND-GAr is one of three detector systems in the design of the DUNE Near Detector complex, which will be located on the Fermilab campus, sixty meters underground and 570 m from the source of an intense neutrino beam. ND-GAr will consist of a cylindrical 10-bar gaseous Argon Time Projection Chamber (TPC) and a surrounding sampling electromagnetic calorimeter embedded within a superconducting solenoid, the cryostat and yoke for which together serve as the pressure vessel. While various options for the specific configuration of ND-GAr are being explored, essential design work for the detector has moved forward in recent months. This document describes basic mechanical, electrostatic, and gas flow design features of the ND-GAr TPC and presents results of electrostatic simulations of the interior of the pressure vessel for both single and dual-anode arrangements. Simulations are implemented with the Elmer finite-element software suite and related programs. Full article
(This article belongs to the Special Issue Selected Papers from "New Horizons in Time Projection Chambers")
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14 pages, 948 KiB  
Article
Multiplicity Distribution and KNO Scaling of Charged Particles Production from pp Collisions at Different Energies
by Mohammed Attia Mahmoud
Particles 2022, 5(2), 96-109; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020009 - 31 Mar 2022
Cited by 1 | Viewed by 2877
Abstract
The multiplicity distribution of charged particles produced from proton–proton collisions at energies s = 2.36, 2.76, 5, 7, 8, 10, 13 and 14 TeV were studied in the present work. Furthermore, multiplicity distribution was studied in different pseudorapidity regions ∣η∣ < [...] Read more.
The multiplicity distribution of charged particles produced from proton–proton collisions at energies s = 2.36, 2.76, 5, 7, 8, 10, 13 and 14 TeV were studied in the present work. Furthermore, multiplicity distribution was studied in different pseudorapidity regions ∣η∣ < 0.5, 1, 1.5, 2, and 2.5. KNO scaling was studied at the same pseudorapidity regions. This is valid in the pseudorapidity region ∣η∣ < 0.5, but with increasing pseudorapidity, the violation increases. The influence of MPI and color reconnection in violation of KNO scaling were studied. The relation between mean multiplicity and collisions energy was explored, noted that it increases with the increasing energy of collisions. Full article
(This article belongs to the Special Issue Particles: Feature Papers)
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