Journal Description

Particles

Particles is an international, open access, peer-reviewed journal covering all aspects of nuclear physics, particle physics and astrophysics science, and is published quarterly online by MDPI.

Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
High Visibility: indexed within ESCI (Web of Science), Inspec, CAPlus / SciFinder, and many other databases.
Rapid Publication: manuscripts are peer-reviewed and a first decision provided to authors approximately 18.8 days after submission; acceptance to publication is undertaken in 5.7 days (median values for papers published in this journal in the second half of 2021).
Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.

Imprint Information Journal Flyer Open Access ISSN: 2571-712X

Latest Articles

Open AccessArticle

Stripping Model for Short Gamma-Ray Bursts in Neutron Star Mergers

and

Particles 2022, 5(2), 198-209; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020018 - 16 Jun 2022

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 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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Open AccessArticle

Approaches to Measuring Direct Photon Yield in A–A Collisions

Dmitri Peresunko

Particles 2022, 5(2), 188-197; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020017 - 09 Jun 2022

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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Open AccessArticle

Diurnal Variations of the Count Rates from Dark Photons in PHELEX

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

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 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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Open AccessArticle

Experimental Determination of the QCD Effective Charge α_g1(Q)

and

Particles 2022, 5(2), 171-179; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020015 - 31 May 2022

Abstract

The QCD effective charge

α_{g_{1}} (Q)

is an observable that characterizes the magnitude of the strong interaction. At high momentum Q, it coincides with the QCD running coupling

α_{s} (Q)

. At low Q, [...] Read more.

The QCD effective charge

α_{g_{1}} (Q)

is an observable that characterizes the magnitude of the strong interaction. At high momentum Q, it coincides with the QCD running coupling

α_{s} (Q)

. At low Q, it offers a nonperturbative definition of the running coupling. We have extracted

α_{g_{1}} (Q)

from measurements carried out at Jefferson Lab that span the very low to moderately high Q domain,

0.14 \leq Q \leq 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

α_{g_{1}} (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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Open AccessArticle

Unruh Effect and Information Entropy Approach

and

Particles 2022, 5(2), 157-170; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020014 - 27 May 2022

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 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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Open AccessArticle

The Novel Scaling of Tsallis Parameters from the Transverse Momentum Spectra of Charged Particles in Heavy-Ion Collisions

and

Particles 2022, 5(2), 146-156; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020013 - 09 May 2022

Abstract

The transverse momentum

(p_{T})

spectra of charged particles measured in Au + Au collisions from the beam energy scan (BES) program, Cu + Cu collisions at

\sqrt{s_{N N}} = 62.4

, 200 GeV at the RHIC and Pb + [...] Read more.

The transverse momentum

(p_{T})

spectra of charged particles measured in Au + Au collisions from the beam energy scan (BES) program, Cu + Cu collisions at

\sqrt{s_{N N}} = 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 / ln \sqrt{s})

and the nonextensive parameter q is presented. Full article

(This article belongs to the Collection High Energy Physics)

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Open AccessArticle

Rabi Frequency Management of Collapsing Quasi-Two-Dimensional Bose-Einstein Condensates with Pseudospin-1/2

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

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 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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Open AccessArticle

Effect of Protoneutron Star Magnetized Envelops in Neutrino Energy Spectra

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

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. 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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Open AccessArticle

Electrostatic Simulations for the DUNE ND-GAr Field Cage

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

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 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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Open AccessArticle

Multiplicity Distribution and KNO Scaling of Charged Particles Production from pp Collisions at Different Energies

Mohammed Attia Mahmoud

Particles 2022, 5(2), 96-109; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020009 - 31 Mar 2022

Abstract

The multiplicity distribution of charged particles produced from proton–proton collisions at energies

\sqrt{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

\sqrt{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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Open AccessArticle

Track Reconstruction in a High-Density Environment with ALICE

and

Particles 2022, 5(1), 84-95; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5010008 - 10 Mar 2022

Abstract

ALICE is the dedicated heavy-ion experiment at the CERN Large Hadron Collider (LHC). Its main tracking and particle-identification detector is a large volume Time Projection Chamber (TPC). The TPC has been designed to perform well in the high-track density environment created in high-energy heavy-ion collisions. In this proceeding, we describe the track reconstruction procedure in ALICE. In particular, we focus on the two main challenges that were faced during the Run 2 data-taking period (2015–2018) of the LHC, which were the baseline fluctuations and the local space charge distortions in the TPC. We present the corresponding solutions in detail and describe the software tools that allowed us to circumvent these challenges. Full article

(This article belongs to the Special Issue Selected Papers from "New Horizons in Time Projection Chambers")

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Open AccessArticle

Techniques for TPC Calibration: Application to Liquid Ar-TPCs

José Maneira

Particles 2022, 5(1), 74-83; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5010007 - 23 Feb 2022

Abstract

Large liquid argon TPCs are playing an increasingly important role in neutrino physics, and their calibration will be an essential component of their capability to reach the required performance and precision. Natural sources are extensively used but present limitations, since natural radioactivity from [...] Read more.

^{39} A r

is of low energy, and the rate of cosmic ray muons is low when the detectors are placed deep underground. Argon gas TPCs have been calibrated with ionizing laser beams for several decades, and more recently the technique has been further developed for use in liquid TPCs. Other recent ideas include the use of external neutron generators creating pulses that propagate into the detector. This paper reviews the development of the laser and neutron methods for the calibration of argon TPCs and describes their planned implementation in the upcoming DUNE experiment. Full article

(This article belongs to the Special Issue Selected Papers from "New Horizons in Time Projection Chambers")

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Open AccessReview

High-Precision Calculations of the Higgs Boson Mass

Edilson Reyes

and

Raffaele Fazio

Particles 2022, 5(1), 53-73; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5010006 - 17 Feb 2022

Abstract

In this paper, we review the status of the computations of the perturbative quantum corrections to the Higgs boson mass in the Standard Model and in its supersymmetric extensions. In particular, supersymmetric theories require a very accurate computation of the Higgs boson mass, which includes corrections even up to the three-loop level, since their predictions are limited by theoretical uncertainties. A discussion about these uncertainties in the context of the Minimal and Next To Minimal Supersymmetric Standard Model is included. Full article

(This article belongs to the Special Issue Higgs Physics)

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Open AccessEditorial

Acknowledgment to Reviewers of Particles in 2021

by Particles Editorial Office

Particles 2022, 5(1), 52; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5010005 - 07 Feb 2022

Abstract

Rigorous peer-reviews are the basis of high-quality academic publishing [...] Full article

Open AccessArticle

Pre-Equilibrium Clustering in Production of Spectator Fragments in Collisions of Relativistic Nuclei

Roman Nepeivoda

Aleksandr Svetlichnyi

Nikita Kozyrev

and

Igor Pshenichnov

Particles 2022, 5(1), 40-51; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5010004 - 29 Jan 2022

Abstract

An algorithm of pre-equilibrium clustering of spectator matter based on the construction of the minimum spanning tree (MST) is presented. The algorithm was implemented in the Abrasion-Ablation Monte Carlo for Colliders (AAMCC) model designed to study the characteristics of spectator matter in collisions [...] Read more.

^{208}

Pb–

^{208}

Pb collisions at the LHC, the agreement of simulation results with experimental data on the average multiplicities of spectator nucleons was improved. The results of the AAMCC-MST were compared with experimental data on the interactions of

^{197}

Au nuclei in nuclear photoemulsion. Comparison of the yields of spectator nuclei calculated for

^{16}

O–

^{16}

O collisions with the yields measured in interactions of

^{16}

O with light nuclei of photoemulsion made it possible to estimate the effect of MST-clustering in small nuclear systems. Full article

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Open AccessArticle

Pioneering the Equation of State of Dense Nuclear Matter with Strange Particles Emitted in Heavy-Ion Collisions: The KaoS Experiment at GSI

Peter Senger

Particles 2022, 5(1), 21-39; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5010003 - 17 Jan 2022

Abstract

High-energy heavy-ion collisions offer the unique possibility to study fundamental properties of nuclear matter in the laboratory, which are relevant for our understanding of the structure of compact stellar objects and the dynamics of neutron star mergers. Of particular interest are the nuclear matter equation of state (EOS), the in-medium modifications of hadrons and the degrees of freedom of matter at high densities and temperatures. Pioneering experiments exploring the EOS for symmetric matter were performed at the SIS18 accelerator of GSI, measuring, as function of beam energy, the collective flow of protons and of light fragments and subthreshold strangeness production. These data were reproduced by various microscopic transport model calculations, providing, up to date, the best constraint for the EOS of symmetric matter with an incompressibility of about 200 MeV for densities up to twice the saturation density. This article reviews the experimental results on subthreshold kaon production together with the theoretical interpretation and gives a brief outlook towards future experiments at higher densities. Full article

(This article belongs to the Collection High Energy Physics)

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Open AccessArticle

Implications of the Conformal Higgs Model

R. K. Nesbet

Particles 2022, 5(1), 12-20; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5010002 - 13 Jan 2022

Abstract

The postulate of universal local Weyl scaling (conformal) symmetry modifies both general relativity and the Higgs scalar field model. The conformal Higgs model (CHM) acquires a cosmological effect that fits the observed accelerating Hubble expansion for redshifts

z \leq 1

(7.33 Gyr) accurately [...] Read more.

z \leq 1

(7.33 Gyr) accurately with only one free constant parameter. Conformal gravity (CG) has recently been fitted to anomalous rotation data for 138 galaxies. Conformal theory explains dark energy and does not require dark matter, providing a viable alternative to the standard ΛCDM paradigm. The theory precludes a massive Higgs particle but validates a composite gauge field

W_{2}

with mass 125 GeV. Full article

(This article belongs to the Special Issue Higgs Physics)

Open AccessArticle

Generic Three-Parameter Wormhole Solution in Einstein-Scalar Field Theory

Bobur Turimov

Ahmadjon Abdujabbarov

Bobomurat Ahmedov

and

Zdeněk Stuchlík

Particles 2022, 5(1), 1-11; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5010001 - 22 Dec 2021

Cited by 1

Abstract

An exact analytical, spherically symmetric, three-parametric wormhole solution has been found in the Einstein-scalar field theory, which covers the several well-known wormhole solutions. It is assumed that the scalar field is massless and depends on the radial coordinate only. The relation between the [...] Read more.

R_{α β} R^{α β} = R^{2}

. The derivation of the Einstein field equations have been explicitly shown, and the exact analytical solution has been found in terms of the three constants of integration. The several wormhole solutions have been extracted for the specific values of the parameters. In order to explore the physical meaning of the integration constants, the solution has been compared with the previously obtained results. The curvature scalar has been determined for all particular solutions. Finally, it is shown that the general solution describes naked singularity characterized by the mass, the scalar quantity and the throat. Full article

Open AccessArticle

The Relation between General Relativity’s Metrics and Special Relativity’s Gravitational Scalar Generalized Potentials and Case Studies on the Schwarzschild Metric, Teleparallel Gravity, and Newtonian Potential

Spyridon Vossos

Elias Vossos

and

Christos G. Massouros

Particles 2021, 4(4), 536-576; https://0-doi-org.brum.beds.ac.uk/10.3390/particles4040039 - 08 Dec 2021

Abstract

This paper shows that gravitational results of general relativity (GR) can be reached by using special relativity (SR) via a SR Lagrangian that derives from the corresponding GR time dilation and vice versa. It also presents a new SR gravitational central scalar generalized [...] Read more.

V = V (r, \dot{r}, \dot{ϕ})

, where r is the distance from the center of gravity and

\dot{r},_{} \dot{ϕ}

are the radial and angular velocity, respectively. This is associated with the Schwarzschild GR time dilation from where a SR scalar generalized potential is obtained, which is exactly equivalent to the Schwarzschild metric. Thus, the Precession of Mercury’s Perihelion, the Gravitational Deflection of Light, the Shapiro time delay, the Gravitational Red Shift, etc., are explained with the use of SR only. The techniques used in this paper can be applied to any GR spacetime metric, Teleparallel Gravity, etc., in order to obtain the corresponding SR gravitational scalar generalized potential and vice versa. Thus, the case study of Newtonian Gravitational Potential according to SR leads to the corresponding non-Riemannian metric of GR. Finally, it is shown that the mainstream consideration of the Gravitational Red Shift contains two approximations, which are valid in weak gravitational fields only. Full article

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Open AccessArticle

Beta Decay in Medium-Mass Nuclei with the In-Medium Similarity Renormalization Group

Steven Ragnar Stroberg

Particles 2021, 4(4), 521-535; https://0-doi-org.brum.beds.ac.uk/10.3390/particles4040038 - 18 Nov 2021

Cited by 2

Abstract

We review the status of ab initio calculations of allowed beta decays (both Fermi and Gamow–Teller), within the framework of the valence-space in-medium similarity renormalization group approach. Full article

(This article belongs to the Special Issue Beta-Decay Processes in Nuclear Systems)

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