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Particles, Volume 4, Issue 1 (March 2021) – 11 articles

Cover Story (view full-size image): The center vortex model of quantum chromodynamics can explain confinement and chiral symmetry breaking by center vortices and closed color magnetic flux lines, percolating the vacuum. Their evolution in time creates a closed surface in four-dimensional spacetime. The SU(2) lattice simulation shows that the curvature of this surface correlates with fluctuations in color space and that color-homogeneous regions of finite size are embedded on the vortex surface. Both observations proved to be stable under Pisa cooling and for the investigated range of lattice spacings, hence they are expected to persist in smoothed lattice configurations. The vortex color structure is related to the chiral condensate. View this paper.
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Article
Properties of SU(2) Center Vortex Structure in Smooth Configurations
Particles 2021, 4(1), 93-105; https://0-doi-org.brum.beds.ac.uk/10.3390/particles4010011 - 03 Mar 2021
Cited by 1 | Viewed by 552
Abstract
New analysis regarding the structure of center vortices is presented: Using data from gluonic SU(2) lattice simulation with Wilson action, a correlation of fluctuations in color space to the curvature of vortex fluxes was found. Finite size effects of the S2-homogeneity hint at [...] Read more.
New analysis regarding the structure of center vortices is presented: Using data from gluonic SU(2) lattice simulation with Wilson action, a correlation of fluctuations in color space to the curvature of vortex fluxes was found. Finite size effects of the S2-homogeneity hint at color homogeneous regions on the vortex surface. Full article
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Article
Event Rates for the Scattering of Weakly Interacting Massive Particles from 23Na and 40Ar
Particles 2021, 4(1), 75-92; https://0-doi-org.brum.beds.ac.uk/10.3390/particles4010010 - 24 Feb 2021
Viewed by 583
Abstract
Detection rates for the elastic and inelastic scattering of weakly interacting massive particles (WIMPs) off 23Na are calculated within the framework of Deformed Shell Model (DSM) based on Hartree-Fock states. At first, the spectroscopic properties of the detector nucleus, like energy spectra and magnetic moments, are evaluated and compared with experimental data. Following the good agreement of these results, DSM wave functions are used for obtaining elastic and inelastic spin structure functions, nuclear structure coefficients and so forth for the WIMP-23Na scattering. Then, the event rates are also computed with a given set of supersymmetric parameters. In the same manner, using DSM wavefunctions, nuclear structure coefficients and event rates for elastic scattering of WIMPs from 40Ar are also obtained. These results for event rates and also for annual modulation will be useful for the ongoing and future WIMP detection experiments involving detector materials with 23Na and 40Ar nuclei. Full article
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Conference Report
Transport Properties in Magnetized Compact Stars
Particles 2021, 4(1), 63-74; https://0-doi-org.brum.beds.ac.uk/10.3390/particles4010009 - 21 Feb 2021
Viewed by 501
Abstract
Transport properties of dense quark matter are discussed in the strong magnetic field, B. B dependence as well as density dependence of the Hall conductivity is discussed, based on the microscopic Kubo formula. We took into account the possibility of the inhomogeneous [...] Read more.
Transport properties of dense quark matter are discussed in the strong magnetic field, B. B dependence as well as density dependence of the Hall conductivity is discussed, based on the microscopic Kubo formula. We took into account the possibility of the inhomogeneous chiral phase at moderate densities, where anomalous Hall effect is intrinsic and resembles the one in Weyl semimetals in condensed matter physics. Some theoretical aspects inherent in anomalous Hall effect are also discussed. Full article
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Conference Report
Reconstruction of Photon Conversions in the MPD Experiment
Particles 2021, 4(1), 55-62; https://0-doi-org.brum.beds.ac.uk/10.3390/particles4010008 - 17 Feb 2021
Viewed by 1031
Abstract
Spectra of thermal photons carry important information on the temperature of the hot and dense medium produced in heavy ion collisions. Photons can be measured via their conversion into electron-positron pairs in the detector material. In this contribution, challenges in the photon reconstruction [...] Read more.
Spectra of thermal photons carry important information on the temperature of the hot and dense medium produced in heavy ion collisions. Photons can be measured via their conversion into electron-positron pairs in the detector material. In this contribution, challenges in the photon reconstruction are discussed and feasibility studies on photon conversion measurements in the future multipurpose detector (MPD) experiment at NICA are presented. The obtained results indicate good prospects for thermal photon measurements. Full article
(This article belongs to the Special Issue Analysis Techniques and Physics Performance Studies for FAIR and NICA)
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Editorial
Particles —First 100 Papers Milestone Achieved
Particles 2021, 4(1), 53-54; https://0-doi-org.brum.beds.ac.uk/10.3390/particles4010007 - 09 Feb 2021
Viewed by 497
Abstract
Particles (ISSN 2571-712X), which is a peer-reviewed, open access journal launched in 2018, has now reached a significant milestone—the 100th paper has been published [...] Full article
Conference Report
Deep Learning Based Impact Parameter Determination for the CBM Experiment
Particles 2021, 4(1), 47-52; https://0-doi-org.brum.beds.ac.uk/10.3390/particles4010006 - 02 Feb 2021
Viewed by 588
Abstract
In this talk we presented a novel technique, based on Deep Learning, to determine the impact parameter of nuclear collisions at the CBM experiment. PointNet based Deep Learning models are trained on UrQMD followed by CBMRoot simulations of Au+Au collisions at 10 A [...] Read more.
In this talk we presented a novel technique, based on Deep Learning, to determine the impact parameter of nuclear collisions at the CBM experiment. PointNet based Deep Learning models are trained on UrQMD followed by CBMRoot simulations of Au+Au collisions at 10 AGeV to reconstruct the impact parameter of collisions from raw experimental data such as hits of the particles in the detector planes, tracks reconstructed from the hits or their combinations. The PointNet models can perform fast, accurate, event-by-event impact parameter determination in heavy ion collision experiments. They are shown to outperform a simple model which maps the track multiplicity to the impact parameter. While conventional methods for centrality classification merely provide an expected impact parameter distribution for a given centrality class, the PointNet models predict the impact parameter from 2–14 fm on an event-by-event basis with a mean error of −0.33 to 0.22 fm. Full article
(This article belongs to the Special Issue Analysis Techniques and Physics Performance Studies for FAIR and NICA)
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Editorial
Acknowledgment to Reviewers of Particles in 2020
Particles 2021, 4(1), 45-46; https://0-doi-org.brum.beds.ac.uk/10.3390/particles4010005 - 28 Jan 2021
Viewed by 534
Abstract
Peer review is the driving force of journal development, and reviewers are gatekeepers who ensure that Particles maintains its standards for the high quality of its published papers [...] Full article
Article
Reduction of the Mass of the Proto-Quark Star during Cooling
Particles 2021, 4(1), 37-44; https://0-doi-org.brum.beds.ac.uk/10.3390/particles4010004 - 06 Jan 2021
Viewed by 668
Abstract
The integral parameters (mass, radius) of hot proto-quark stars that are formed in supernova explosion are studied. We use the MIT bag model to determine the pressure of up-down and strage quark matter at finite temperature and in the regime where neutrinos are [...] Read more.
The integral parameters (mass, radius) of hot proto-quark stars that are formed in supernova explosion are studied. We use the MIT bag model to determine the pressure of up-down and strage quark matter at finite temperature and in the regime where neutrinos are trapped. It is shown that such stars are heated to temperatures of the order of tens of MeV. The maximum possible values of the central temperatures of these stars are determined. It is shown that the energy of neutrinos that are emitted from proto-quark stars is of the order of 250÷300 MeV. Once formed, the proto-quark stars cool by neutrino emission, which leads to a decrease in the mass of these stars by about 0.16–0.25 M for stars with the rest masses that are in the range Mb=1.221.62 M. Full article
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Conference Report
Resonance Reconstruction in the MPD
Particles 2021, 4(1), 29-36; https://0-doi-org.brum.beds.ac.uk/10.3390/particles4010003 - 06 Jan 2021
Cited by 2 | Viewed by 649
Abstract
The study of hadronic resonance production is an essential part of the physical programs of many heavy-ion experiments. Detailed measurement of the resonance properties is also foreseen in the future Multi-Purpose Detector (MPD) experiment at the NICA collider. In this report, we focus [...] Read more.
The study of hadronic resonance production is an essential part of the physical programs of many heavy-ion experiments. Detailed measurement of the resonance properties is also foreseen in the future Multi-Purpose Detector (MPD) experiment at the NICA collider. In this report, we focus on the experimental challenges for the reconstruction of resonances in heavy-ion experiments and examine the MPD capabilities for the reconstruction of ρ(770)0, K*(892)0,±, φ(1020), Λ(1520), Σ(1385)± and Ξ(1530)0. Full article
(This article belongs to the Special Issue Analysis Techniques and Physics Performance Studies for FAIR and NICA)
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Article
Analysis of the Alignment of Non-Random Patterns of Spin Directions in Populations of Spiral Galaxies
Particles 2021, 4(1), 11-28; https://0-doi-org.brum.beds.ac.uk/10.3390/particles4010002 - 05 Jan 2021
Viewed by 653
Abstract
Observations of non-random distribution of galaxies with opposite spin directions have recently attracted considerable attention. Here, a method for identifying cosine-dependence in a dataset of galaxies annotated by their spin directions is described in the light of different aspects that can impact the [...] Read more.
Observations of non-random distribution of galaxies with opposite spin directions have recently attracted considerable attention. Here, a method for identifying cosine-dependence in a dataset of galaxies annotated by their spin directions is described in the light of different aspects that can impact the statistical analysis of the data. These aspects include the presence of duplicate objects in a dataset, errors in the galaxy annotation process, and non-random distribution of the asymmetry that does not necessarily form a dipole or quadrupole axes. The results show that duplicate objects in the dataset can artificially increase the likelihood of cosine dependence detected in the data, but a very high number of duplicate objects is required to lead to a false detection of an axis. Inaccuracy in galaxy annotations has relatively minor impact on the identification of cosine dependence when the error is randomly distributed between clockwise and counterclockwise galaxies. However, when the error is not random, even a small bias of 1% leads to a statistically significant cosine dependence that peaks at the celestial pole. Experiments with artificial datasets in which the distribution was not random showed strong cosine dependence even when the data did not form a full dipole axis alignment. The analysis when using the unmodified data shows asymmetry profile similar to the profile shown in multiple previous studies using several different telescopes. Full article
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Conference Report
Short-Lived Resonances as Probes of the Medium Produced in Heavy-Ion Collisions
Particles 2021, 4(1), 1-10; https://0-doi-org.brum.beds.ac.uk/10.3390/particles4010001 - 25 Dec 2020
Cited by 1 | Viewed by 769
Abstract
Hadronic resonances play an important role in the study of the physics of heavy-ion collisions. In these proceedings, we discuss how the resonances can probe the reaction dynamics, the strangeness production and the properties of the hadronic phase in heavy-ion collisions at center-of-mass [...] Read more.
Hadronic resonances play an important role in the study of the physics of heavy-ion collisions. In these proceedings, we discuss how the resonances can probe the reaction dynamics, the strangeness production and the properties of the hadronic phase in heavy-ion collisions at center-of-mass energies of sNN = 4–11 GeV. The resonance properties predicted by the general-purpose event generators are found to be very sensitive to the properties and space-time evolution of the medium produced in heavy-ion collisions. Full article
(This article belongs to the Special Issue Analysis Techniques and Physics Performance Studies for FAIR and NICA)
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