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Particles
Number of Followers: 0 Open Access journal ISSN (Online) 2571-712X Published by MDPI [258 journals] |
- Particles, Vol. 6, Pages 876-885: Diquarks and Λ0/π+,
Ξ−/π+ Ratios in the Framework of the EPNJL Model
Authors: Alexandra Friesen, Yuriy Kalinovsky
First page: 876
Abstract: The applicability of the effective models to the description of baryons and the behaviour of ratios of strange baryons to pions is discussed. In the framework of the EPNJL model, the Bethe–Salpeter equation is used to find masses of baryons, which are considered to be in a diquark-quark state. Baryon melting is discussed at a finite chemical potential, and a flavor dependence of the hadronic deconfinement temperature is pointed out. It is shown that the description of the diquark-quark state at finite chemical potential is limited due to the occurrence of Bose condensate. This effect is strongly manifested in the description of light diquarks and baryons. Both the Λ0/π+ and Ξ−/π+ ratios show a sharp behaviour as functions of the T/μB variable, where T and μB are calculated along the melting lines.
Citation: Particles
PubDate: 2023-10-10
DOI: 10.3390/particles6040056
Issue No: Vol. 6, No. 4 (2023)
- Particles, Vol. 6, Pages 886-897: Effect of a Wake-Field on the
Dissociation of Quarkonium in Collisional Quark–Gluon Plasma
Authors: Yernur Kuanyshbaiuly, Ardak Junissov, Mukhit Muratov
First page: 886
Abstract: We have studied wake effects on the dissociation of heavy quarkonia states J/ψ and Y by introducing an in-medium modification to the inter-quark potential. The wakes in the quark–gluon plasma were modeled using linear response theory using a dynamic dielectric function obtained from kinetic theory (Boltzmann equation) with a Bhatnagar–Gross–Krook (BGK) collision term. The in-medium modified potential was used to investigate the dissociation character depending on various parameters such as the velocity of quarkonium moving through the medium and the collision frequency. We have also calculated critical values of the dissociation temperature. Modifications of the dissociation energy due to wake-field effects were found.
Citation: Particles
PubDate: 2023-10-12
DOI: 10.3390/particles6040057
Issue No: Vol. 6, No. 4 (2023)
- Particles, Vol. 6, Pages 898-912: Development of a Combined Horizontal and
Vertical Correcting Magnet for Siam Photon Source II
Authors: Supachai Prawanta, Prapaiwan Sunwong, Pariwat Singthong, Thongchai Leetha, Pajeeraphorn Numanoy, Warissara Tangyotkhajorn, Apichai Kwankasem, Visitchai Sooksrimuang, Sukho Kongtawong, Supat Klinkiew
First page: 898
Abstract: A prototype of a combined horizontal and vertical correcting magnet was designed and fabricated for the 3 GeV storage ring of Siam Photon Source II, which will be the second synchrotron light source in Thailand. The magnet will be employed for fast-orbit feedback correction, with a required magnetic field integral of approximately 8 Tesla.mm. The magnet pole and yoke were manufactured using laminated silicon steel to minimize hysteresis and eddy current losses during operation. Magnet modeling and magnetic field calculations were performed using Opera-3D. The size of the gap between the magnet poles is limited by the size of the vacuum chamber over which the magnet will be installed; in this case, it was designed to be 65 mm. Mechanical analysis of the structure of the magnet was performed using SOLIDWORKS and ANSYS. Magnetic field measurements were obtained using the Hall probe technique. The entire prototype, from its design to manufacturing and measurement, was completed in-house. This design will be appropriate for application at the Siam Photon Source II storage ring.
Citation: Particles
PubDate: 2023-10-13
DOI: 10.3390/particles6040058
Issue No: Vol. 6, No. 4 (2023)
- Particles, Vol. 6, Pages 913-922: Poincaré–Chetaev Equations
in Dirac’s Formalism of Constrained Systems
Authors: Alexei A. Deriglazov
First page: 913
Abstract: We single out a class of Lagrangians on a group manifold, for which one can introduce non-canonical coordinates in the phase space, which simplify the construction of the Poisson structure without explicitly calculating the Dirac bracket. In the case of the SO(3) manifold, the application of this formalism leads to the Poincaré–Chetaev equations. The general solution to these equations is written in terms of an exponential of the Hamiltonian vector field.
Citation: Particles
PubDate: 2023-10-13
DOI: 10.3390/particles6040059
Issue No: Vol. 6, No. 4 (2023)
- Particles, Vol. 6, Pages 923-942: Order, Chaos and Born’s
Distribution of Bohmian Particles
Authors: Athanasios C. Tzemos, George Contopoulos
First page: 923
Abstract: We study order, chaos and ergodicity in the Bohmian trajectories of a 2D quantum harmonic oscillator. We first present all the possible types (chaotic, ordered) of Bohmian trajectories in wavefunctions made of superpositions of two and three energy eigenstates of the oscillator. There is no chaos in the case of two terms and in some cases of three terms. Then, we show the different geometries of nodal points in bipartite Bohmian systems of entangled qubits. Finally, we study multinodal wavefunctions and find that a large number of nodal points does not always imply the dominance of chaos. We show that, in some cases, the Born distribution is dominated by ordered trajectories, something that has a significant impact on the accessibility of Born’s rule P= Ψ 2 by initial distributions of Bohmian particles with P0≠ Ψ0 2.
Citation: Particles
PubDate: 2023-11-01
DOI: 10.3390/particles6040060
Issue No: Vol. 6, No. 4 (2023)
- Particles, Vol. 6, Pages 943-974: Off-Shell Duality Invariance of
Schwarzschild Perturbation Theory
Authors: Adam R. Solomon
First page: 943
Abstract: We explore the duality invariance of the Maxwell and linearized Einstein–Hilbert actions on a non-rotating black hole background. On-shell, these symmetries are electric–magnetic duality and Chandrasekhar duality, respectively. Off-shell, they lead to conserved quantities; we demonstrate that one of the consequences of these conservation laws is that even- and odd-parity metric perturbations have equal Love numbers. Along the way, we derive an action principle for the Fackerell–Ipser equation and Teukolsky–Starobinsky identities in electromagnetism.
Citation: Particles
PubDate: 2023-11-07
DOI: 10.3390/particles6040061
Issue No: Vol. 6, No. 4 (2023)
- Particles, Vol. 6, Pages 975-992: Neutrino Masses in Supersymmetric Models
with R-Symmetry
Authors: Marcos Cardoso Rodriguez, Ion Vasile Vancea
First page: 975
Abstract: In this article, we give a brief review of the origin of the neutrino mass in some interesting non-linear supersymmetric models with R-symmetry. These models are able to address and solve the most important problems of particle physics and provide mechanisms for neutrino mass generation and their mixing parameters in agreement with the current experimental data. Their prediction could be experimentally tested in the near future by collider experiments.
Citation: Particles
PubDate: 2023-11-08
DOI: 10.3390/particles6040062
Issue No: Vol. 6, No. 4 (2023)
- Particles, Vol. 6, Pages 993-1008: Finiteness of N=4
Super-Yang–Mills Effective Action in Terms of Dressed N=1
Superfields
Authors: Igor Kondrashuk, Ivan Schmidt
First page: 993
Abstract: We argue in favor of the independence on any scale, ultraviolet or infrared, in kernels of the effective action expressed in terms of dressed N=1 superfields for the case of N=4 super-Yang–Mills theory. Under “scale independence” of the effective action of dressed mean superfields, we mean its “finiteness in the off-shell limit of removing all the regularizations”. This off-shell limit is scale independent because no scale remains inside these kernels after removing the regularizations. We use two types of regularization: regularization by dimensional reduction and regularization by higher derivatives in its supersymmetric form. Based on the Slavnov–Taylor identity, we show that dressed fields of matter and of vector multiplets can be introduced to express the effective action in terms of them. Kernels of the effective action expressed in terms of such dressed effective fields do not depend on the ultraviolet scale. In the case of dimensional reduction, by using the developed technique, we show how the problem of inconsistency of the dimensional reduction can be solved. Using Piguet and Sibold formalism, we indicate that the dependence on the infrared scale disappears off shell in both the regularizations.
Citation: Particles
PubDate: 2023-11-08
DOI: 10.3390/particles6040063
Issue No: Vol. 6, No. 4 (2023)
- Particles, Vol. 6, Pages 682-692: Neutrino Spectrum and Energy Loss Rates
Due to Weak Processes on Hot 56Fe in Pre-Supernova Environment
Authors: A. A. Dzhioev, A. V. Yudin, N. V. Dunina-Barkovskaya, A. I. Vdovin
First page: 682
Abstract: Applying TQRPA calculations of Gamow–Teller strength functions in hot nuclei, we compute the (anti)neutrino spectra and energy loss rates arising from weak processes on hot 56Fe under pre-supernova conditions. We use a realistic pre-supernova model calculated by the stellar evolution code MESA. Taking into account both charged and neutral current processes, we demonstrate that weak reactions with hot nuclei can produce high-energy (anti)neutrinos. We also show that, for hot nuclei, the energy loss via (anti)neutrino emission is significantly larger than that for nuclei in their ground state. It is found that the neutral current de-excitation via the νν¯-pair emission is presumably a dominant source of antineutrinos. In accordance with other studies, we confirm that the so-called single-state approximation for neutrino spectra might fail under certain pre-supernova conditions.
Citation: Particles
PubDate: 2023-06-28
DOI: 10.3390/particles6030041
Issue No: Vol. 6, No. 3 (2023)
- Particles, Vol. 6, Pages 693-702: Study of Coherent Smith–Purcell
Radiation in the Terahertz Region Using Ultra-Short Electron Bunches
Authors: Hiroki Yamada, Toshiya Muto, Fujio Hinode, Shigeru Kashiwagi, Ken-ichi Nanbu, Ken Kanomata, Ikuro Nagasawa, Ken Takahashi, Koutaro Shibata, Hiroyuki Hama
First page: 693
Abstract: Smith–Purcell radiation (SPR) can be generated nondestructively, providing valuable applications in light sources and beam monitors. Coherent SPR is expected to enable single-shot measurements of very short bunch lengths on the fs scale. Since the reconstruction of the longitudinal bunch shape from the coherent SPR is based on the reliable SPR spectrum, a more detailed understanding of the properties of the radiation is important in this context. Employing a 100 fs ultrashort electron bunch at the t-ACTS test accelerator, the spectrum, angular distribution, and polarization of the produced coherent SPR were measured in the terahertz frequency region and compared with a model calculation. In addition to the widely known surface current model evaluation, the effect of the geometrical shading effect on induced currents on metal surfaces was evaluated using 3D numerical calculations. The obtained SPR characteristics are also presented. In the evaluation of the grating with a shallow blaze angle, it was found that the shading effect has a non-negligible effect on the generated SPR intensity; the measured angular distribution and polarization results were in good agreement with this result.
Citation: Particles
PubDate: 2023-07-03
DOI: 10.3390/particles6030042
Issue No: Vol. 6, No. 3 (2023)
- Particles, Vol. 6, Pages 703-712: Electron Energy Spectrometer for MIR-THz
FEL Light Source at Chiang Mai University
Authors: Kittipong Techakaew, Kanlayaporn Kongmali, Sakhorn Rimjaem
First page: 703
Abstract: The linear accelerator system of the PBP-CMU Electron Linac Laboratory has been designed with the aim of generating free-electron lasers (FELs) in the mid-infrared (MIR) and terahertz (THz) regions. The quality of the radiation is strongly dependent on the properties of the electron beam. Among the important beam parameters, the electron beam energy and energy spread are particularly important. To accurately measure the electron beam energy, the first dipole magnet in the bunch compressor system and the downstream screen station are employed as an energy spectrometer. The A Space Charge Tracking Algorithm (ASTRA) software is used for the design and optimization of this system. Simulation results demonstrate that the developed spectrometer is capable of accurately measuring the energy within the 5–25 MeV range. The screen station system is designed and constructed to have the ability to capture a beam size with a resolution of 0.1 mm per pixel. This resolution is achieved with a screen-to-camera distance of 1.2 m, which proves sufficient for precise energy measurement. The systematic error in energy measurement is found to be less than 10%, with a minimum energy spread of 0.4% achievable when the horizontal beam size remains below 3 mm.
Citation: Particles
PubDate: 2023-07-07
DOI: 10.3390/particles6030043
Issue No: Vol. 6, No. 3 (2023)
- Particles, Vol. 6, Pages 713-730: Impact of Multiple Phase Transitions in
Dense QCD on Compact Stars
Authors: Armen Sedrakian
First page: 713
Abstract: This review covers several recent developments in the physics of dense QCD with an emphasis on the impact of multiple phase transitions on astrophysical manifestations of compact stars. To motivate the multi-phase modeling of dense QCD and delineate the perspectives, we start with a discussion of the structure of its phase diagram and the arrangement of possible color-superconducting and other phases. It is conjectured that pair-correlated quark matter in β-equilibrium is within the same universality class as spin-imbalanced cold atoms and the isospin asymmetrical nucleonic matter. This then implies the emergence of phases with broken space symmetries and tri-critical (Lifshitz) points. The beyond-mean-field structure of the quark propagator and its non-trivial implications are discussed in the cases of two- and three-flavor quark matter within the Eliashberg theory, which takes into account the frequency dependence (retardation) of the gap function. We then construct an equation of state (EoS) that extends the two-phase EoS of dense quark matter within the constant speed of sound parameterization by adding a conformal fluid with a speed of sound cconf.=1/3 at densities ≥10nsat, where nsat is the saturation density. With this input, we construct static, spherically symmetrical compact hybrid stars in the mass–radius diagram, recover such features as the twins and triplets, and show that the transition to conformal fluid leads to the spiraling-in of the tracks in this diagram. Stars on the spirals are classically unstable with respect to the radial oscillations but can be stabilized if the conversion timescale between quark and nucleonic phases at their interface is larger than the oscillation period. Finally, we review the impact of a transition from high-temperature gapped to low-temperature gapless two-flavor phase on the thermal evolution of hybrid stars.
Citation: Particles
PubDate: 2023-07-14
DOI: 10.3390/particles6030044
Issue No: Vol. 6, No. 3 (2023)
- Particles, Vol. 6, Pages 731-738: Pre/Post-Merger Consistency Test for
Gravitational Signals from Binary Neutron Star Mergers
Authors: Matteo Breschi, Gregorio Carullo, Sebastiano Bernuzzi
First page: 731
Abstract: Gravitational waves from binary neutron star (BNS) mergers can constrain nuclear models, predicting their equation of state (EOS). Matter effects on the inspiral-merger signal are encoded in the multipolar tidal polarizability parameters, whose leading order combination is sufficient to capture, with high accuracy, the key features of the merger waveform. Similar EOS-insensitive relations exist for the post-merger signal and can be used to model the emissions from the remnant. Several works suggested that the appearance of new degrees of freedom in high-density post-merger matter can be inferred by observing a violation of these EOS-insensitive relations. Here, we demonstrate a Bayesian method to test such an EOS-insensitive relation between the tidal polarizability parameters (or any other equivalent parameter) and the dominant post-merger frequency using information from the pre-and-post-merger signal. Technically, the method is similar to the inspiral-merger-ringdown consistency tests of General Relativity with binary black holes. However, differently from the latter, BNS pre/post-merger consistency tests are conceptually less informative and they only address the consistency of the assumed EOS-insensitive relation. Specifically, we discuss how such tests cannot conclusively discriminate between an EOS without respecting such a relation and the appearance of new degrees of freedom (or phase transitions) in high-density matter.
Citation: Particles
PubDate: 2023-07-14
DOI: 10.3390/particles6030045
Issue No: Vol. 6, No. 3 (2023)
- Particles, Vol. 6, Pages 739-745: Amplitude and Phase Control of RF Pulse
Using IQ Modulator to Improve Electron Beam Quality
Authors: Shimon Yamada, Shigeru Kashiwagi, Ikuro Nagasawa, Ken-ichi Nanbu, Toshiya Muto, Ken Takahashi, Ken Kanomata, Kotaro Shibata, Fujio Hinode, Sadao Miura, Hiroki Yamada, Kohei Kumagai, Hiroyuki Hama
First page: 739
Abstract: A test-Accelerator as Coherent Terahertz Source (t-ACTS) has been under development at Tohoku University, in which an intense coherent terahertz radiation is generated from the short electron bunches. Velocity bunching scheme in a traveling wave accelerating structure is employed to generate the short electron bunches. The in-phase and quadrature (IQ) modulator and demodulator were installed to the low-level RF systems of t-ACTS linac to control and measure the amplitude and phase of RF power. The amplitude and phase of the RF power applied to an RF electron gun cavities and the accelerating structure are controlled to produce the electron bunches with a uniform and small momentum spread suitable for the velocity bunching. By installing the feed-forward control system using IQ modulators for the beam conditioning, we have successfully generated flat RF pulses and improved beam quality, including the energy spectrum of the beam. The details of feed-forward control system of the amplitude and phase using the IQ modulator and the beam experiments are presented in this paper.
Citation: Particles
PubDate: 2023-07-18
DOI: 10.3390/particles6030046
Issue No: Vol. 6, No. 3 (2023)
- Particles, Vol. 6, Pages 746-761: R-Symmetries and Curvature Constraints
in A-Twisted Heterotic Landau–Ginzburg Models
Authors: Richard S. Garavuso
First page: 746
Abstract: In this paper, we discuss various aspects of a class of A-twisted heterotic Landau–Ginzburg models on a Kähler variety X. We provide a classification of the R-symmetries in these models which allow the A-twist to be implemented, focusing on the case in which the gauge bundle is either a deformation of the tangent bundle of X or a deformation of a sub-bundle of the tangent bundle of X. Some anomaly-free examples are provided. The curvature constraint imposed by supersymmetry in these models when the superpotential is not holomorphic is reviewed. Constraints of this nature have been used to establish properties of analogues of pullbacks of Mathai–Quillen forms which arise in the correlation functions of the corresponding A-twisted or B-twisted heterotic Landau–Ginzburg models. The analogue most relevant to this paper is a deformation of the pullback of a Mathai–Quillen form. We discuss how this deformation may arise in the class of models studied in this paper. We then comment on how analogues of pullbacks of Mathai–Quillen forms not discussed in previous work may be obtained. Standard Mathai–Quillen formalism is reviewed in an appendix. We also include an appendix which discusses the deformation of the pullback of a Mathai–Quillen form.
Citation: Particles
PubDate: 2023-08-07
DOI: 10.3390/particles6030047
Issue No: Vol. 6, No. 3 (2023)
- Particles, Vol. 6, Pages 762-770: Supersymmetric AdS Solitons, Ground
States, and Phase Transitions in Maximal Gauged Supergravity
Authors: Antonio Gallerati
First page: 762
Abstract: We review some recent soliton solutions in a class of four-dimensional supergravity theories. The latter can be obtained from black hole solutions by means of a double Wick rotation. For special values of the parameters, the new configurations can be embedded in the gauged maximal N=8 theory and uplifted in the higher-dimensional D=11 theory. We also consider BPS soliton solutions, preserving a certain fraction of supersymmetry.
Citation: Particles
PubDate: 2023-08-12
DOI: 10.3390/particles6030048
Issue No: Vol. 6, No. 3 (2023)
- Particles, Vol. 6, Pages 771-783: Net-Baryon Probability Distributions
from Lattice Simulations
Authors: Roman Rogalyov, Vladimir Goy
First page: 771
Abstract: We use the results of lattice simulations of the net-baryon number density at imaginary baryon chemical potential in Nf=2 QCD to construct the equation of state of dense and hot strong-interacting matter both above the Roberge–Weiss temperature T>TRW and below the critical temperature T<Tc. For these cases, we also evaluate probability distributions of the net-baryon number, as well as the respective cumulants and moments. The consequences of the asymptotic behavior of these probability distributions for the problem of reconstruction of the net-baryon probability distributions from cumulants are discussed.
Citation: Particles
PubDate: 2023-08-23
DOI: 10.3390/particles6030049
Issue No: Vol. 6, No. 3 (2023)
- Particles, Vol. 6, Pages 784-800: Stripping Model for Short GRBs: The
Impact of Nuclear Data
Authors: Andrey Yudin, Nikita Kramarev, Igor Panov, Anton Ignatovskiy
First page: 784
Abstract: We investigate the impact of forthcoming nuclear data on the predictions of the neutron star (NS) stripping model for short gamma-ray bursts. The main area to which we pay attention is the NS crust. We show that the uncertain properties of the NS equation of state can significantly influence the stripping time tstr, the main dynamical parameter of the model. Based on the known time delay (tstr≈1.7 s) between the peak of the gravitational wave signal GW170817 and the detection of gamma photons from GRB170817A, we obtain new restrictions on the nuclear matter parameters, in particular, the symmetry energy slope parameter: L<114.5MeV. In addition, we study the process of nucleosynthesis in the outer and inner crusts of a low-mass NS. We show that the nucleosynthesis is strongly influenced by both the forthcoming nuclear data and the equation of state of the NS matter.
Citation: Particles
PubDate: 2023-08-24
DOI: 10.3390/particles6030050
Issue No: Vol. 6, No. 3 (2023)
- Particles, Vol. 6, Pages 801-818: Exploring the Interaction of Cosmic Rays
with Water by Using an Old-Style Detector and Rossi’s Method
Authors: Marco Arcani, Domenico Liguori, Andrea Grana
First page: 801
Abstract: Cosmic ray air showers are a phenomenon that can be observed on Earth when high-energy particles from outer space collide with the Earth’s atmosphere. These energetic particles in space are called primary cosmic rays and consist mainly of protons (about 89%), along with nuclei of helium (10%) and heavier nuclei (1%). Particles resulting from interactions in the atmosphere are called secondary cosmic rays. The composition of air showers in the atmosphere can include several high-energy particles such as mesons, electrons, muons, photons, and others, depending on the energy and type of the primary cosmic ray. Other than air, primary cosmic rays can also produce showers of particles when they interact with any type of matter; for instance, particle showers are also produced within the soil of planets without an atmosphere. In the same way, secondary cosmic particles can start showers of tertiary particles in any substance. In the 1930s, Bruno Rossi conducted an experiment to measure the energy loss of secondary cosmic rays passing through thin metal sheets. Surprisingly, he observed that as the thickness of the metal sheets increased, the number of particles emerging from the metal also increased. However, by adding more metal sheets, the number of particles eventually decreased. This was consistent with the expectation that cosmic rays were interacting with the atoms in the metals and losing energy to produce multiple secondary particles. In this paper, we describe a new–old approach for measuring particle showers in water using a cosmic ray telescope and Rossi’s method. Our instrument consists of four Geiger–Müller tubes (GMT) arranged to detect muons and particle showers. GMT sensors are highly sensitive devices capable of detecting electrons and gamma rays with energies ranging from a few tens of keV up to several tens of MeV. Since Rossi studied the effects caused by cosmic rays as they pass through metals, we wondered if the same process could also happen in water. We present results from a series of experiments conducted with this instrument, demonstrating its ability to detect and measure particle showers produced by the interaction of cosmic rays in water with good confidence. To the best of our knowledge, this experiment has never been conducted before. Our approach offers a low-cost and easy-to-use alternative to more sophisticated cosmic ray detectors, making it accessible to a wider range of researchers and students.
Citation: Particles
PubDate: 2023-08-30
DOI: 10.3390/particles6030051
Issue No: Vol. 6, No. 3 (2023)
- Particles, Vol. 6, Pages 819-833: Is the Universe Anisotropic Right Now'
Comparing the Real Universe with the Kasner’s Space-Time
Authors: Serge Parnovsky
First page: 819
Abstract: We investigate possible astronomical manifestations of space-time anisotropy. The homogeneous vacuum Kasner solution was chosen as a reference anisotropic cosmological model because there are no effects caused by inhomogeneity in this simple model with a constant degree of anisotropy. This anisotropy cannot become weak. The study of its geodesic structure made it possible to clarify the properties of this space-time. It showed that the degree of manifestation of anisotropy varies significantly depending on the travel time of the light from the observed object. For nearby objects, for which it does not exceed half the age of the universe, the manifestations of anisotropy are very small. Distant objects show more pronounced manifestations; for example, in the distribution of objects over the sky and over photometric distances. These effects for each of the individual objects decrease with time but, in general, the manifestations of anisotropy in the Kasner space-time remain constant due to the fact that new sources come from beyond the cosmological horizon. We analyze observable signatures of the Kasner-type anisotropy and compare it to observations. These effects were not found in astronomical observations, including the study of the CMB. We can assume that the Universe has always been isotropic or almost isotropic since the recombination era. This does not exclude the possibility of its significant anisotropy at the moment of the Big Bang followed by rapid isotropization during the inflationary epoch.
Citation: Particles
PubDate: 2023-09-07
DOI: 10.3390/particles6030052
Issue No: Vol. 6, No. 3 (2023)
- Particles, Vol. 6, Pages 834-846: Lee–Yang Zeroes in the Baryon
Fugacity Plane: The Role of High Densities
Authors: Nikolai Gerasimeniuk, Vitaly Bornyakov, Vladimir Goy, Roman Rogalyov, Anatolii Korneev, Alexander Molochkov, Atsushi Nakamura
First page: 834
Abstract: We compute the canonical partition functions and the Lee–Yang zeros in Nf=2 lattice QCD at temperature T=1.20Tc lying above the Roberge–Weiss phase transition temperature TRW. The phase transition is characterized by the discontinuities in the baryon number density at specific values of imaginary baryon chemical potential. We further develop our method to compute the canonical partition functions using the asymptotic expression for respective integral. Then, we compute the Lee–Yang zeros and study their behavior in the limit of high baryon density.
Citation: Particles
PubDate: 2023-09-07
DOI: 10.3390/particles6030053
Issue No: Vol. 6, No. 3 (2023)
- Particles, Vol. 6, Pages 847-863: Hyperonic Interactions in Neutron Stars
Authors: Semyon Mikheev, Dmitry Lanskoy, Artur Nasakin, Tatiana Tretyakova
First page: 847
Abstract: The matter of neutron stars is characterised by the density of the order of typical nuclear densities; hence, it can be described with methods of nuclear physics. However, at high densities, some effects that are absent in nuclear and hypernuclear physics can appear, and this makes neutron stars a good place for studying the properties of baryonic interactions. In the present work, we consider neutron stars consisting of nucleons, leptons and Λ hyperons with Skyrme baryonic forces. We study the character of the ΛN interactions taking place in neutron stars at high densities. In particular, we show the difference between three-body ΛNN and density-dependent ΛN forces. We also demonstrate that the Skyrme ΛN forces proportional to nuclear density are better suited for the modelling of neutron stars than the forces proportional to fractional powers of density. Finally, we emphasize the importance of the point of appearance of hyperons in a further search for parameterizations which are suitable for describing neutron stars.
Citation: Particles
PubDate: 2023-09-08
DOI: 10.3390/particles6030054
Issue No: Vol. 6, No. 3 (2023)
- Particles, Vol. 6, Pages 864-875: Unruh Entropy of a Schwarzschild Black
Hole
Authors: Maksym Teslyk, Olena Teslyk, Larissa Bravina, Evgeny Zabrodin
First page: 864
Abstract: The entropy produced by Unruh radiation is estimated and compared to the entropy of a Schwarzschild black hole. We simulate a spherical system of mass M by a set of Unruh horizons and estimate the total entropy of the outgoing radiation. Dependence on the mass and spin of the emitted particles is taken into account. The obtained results can be easily extended to any other intrinsic degrees of freedom of outgoing particles. The ratio of Unruh entropy to the Schwarzschild black hole entropy is derived in exact analytical form. For large black holes, this ratio exhibits high susceptibility to quantum numbers, e.g., spin s, of emitted quanta and varies from 0% for s=0 to 19.0% for s=5/2.
Citation: Particles
PubDate: 2023-09-14
DOI: 10.3390/particles6030055
Issue No: Vol. 6, No. 3 (2023)
- Particles, Vol. 6, Pages 470-484: Chaos in QCD' Gap Equations and
Their Fractal Properties
Authors: Thomas Klähn, Lee C. Loveridge, Mateusz Cierniak
First page: 470
Abstract: In this study, we discuss how iterative solutions of QCD-inspired gap-equations at the finite chemical potential demonstrate domains of chaotic behavior as well as non-chaotic domains, which represent one or the other of the only two—usually distinct—positive mass gap solutions with broken or restored chiral symmetry, respectively. In the iterative approach, gap solutions exist which exhibit restored chiral symmetry beyond a certain dynamical cut-off energy. A chirally broken, non-chaotic domain with no emergent mass poles and hence with no quasi-particle excitations exists below this energy cut-off. The transition domain between these two energy-separated domains is chaotic. As a result, the dispersion relation is that of quarks with restored chiral symmetry, cut at a dynamical energy scale, and determined by fractal structures. We argue that the chaotic origin of the infrared cut-off could hint at a chaotic nature of confinement and the deconfinement phase transition.
Citation: Particles
PubDate: 2023-04-11
DOI: 10.3390/particles6020026
Issue No: Vol. 6, No. 2 (2023)
- Particles, Vol. 6, Pages 485-496: A Monte Carlo Study of Hyperon
Production with the MPD and BM@N Experiments at NICA
Authors: Alexander Zinchenko, Mikhail Kapishin, Viktar Kireyeu, Vadim Kolesnikov, Alexander Mudrokh, Dilyana Suvarieva, Veronika Vasendina, Dmitry Zinchenko
First page: 485
Abstract: Study of the strangeness production in heavy-ion collisions is one of the most important parts of the physics program of the BM@N and MPD experiments at the NICA accelerator complex. With collision energies sNN of 2.3–3.3 GeV in the fixed target mode at BM@N and 4–11 GeV in the collider mode at MPD, the experiments will cover the region of the maximum net baryon density and provide high-statistics complementary data on different physics probes. In this paper, some results of Monte Carlo studies of hyperon production with the BM@N and MPD experiments are presented, demonstrating their performance for investigation of the objects with strangeness.
Citation: Particles
PubDate: 2023-04-18
DOI: 10.3390/particles6020027
Issue No: Vol. 6, No. 2 (2023)
- Particles, Vol. 6, Pages 497-514: Centrality Selection Effect on Elliptic
Flow Measurements in Relativistic Heavy-Ion Collisions at NICA Energies
Authors: Dim Idrisov, Petr Parfenov, Arkadiy Taranenko
First page: 497
Abstract: The elliptic flow (v2) of produced particles is one of the important observables sensitive to the transport properties of the strongly interacting matter created in relativistic heavy-ion collisions. Detailed differential measurements of v2 are also foreseen in the future Multi-Purpose Detector (MPD) experiment at the Nuclotron based Ion Collider fAcility (NICA) at collision energies sNN = 4–11 GeV. Elliptic flow strongly depends on collision geometry, defined by the impact parameter b. Usually b is an input to theoretical calculations and can be deduced from experimental observables in the final state using the centrality procedure. In this work, we investigate the influence of the choice of centrality procedure on the elliptic flow measurements at NICA energies.
Citation: Particles
PubDate: 2023-04-26
DOI: 10.3390/particles6020028
Issue No: Vol. 6, No. 2 (2023)
- Particles, Vol. 6, Pages 515-545: Several Topics on Transverse
Momentum-Dependent Fragmentation Functions
Authors: Kai-Bao Chen, Tianbo Liu, Yu-Kun Song, Shu-Yi Wei
First page: 515
Abstract: The hadronization of a high-energy parton is described by fragmentation functions which are introduced through QCD factorizations. While the hadronization mechanism per se remains uknown, fragmentation functions can still be investigated qualitatively and quantitatively. The qualitative study mainly concentrates on extracting genuine features based on the operator definition in quantum field theory. The quantitative research focuses on describing a variety of experimental data employing the fragmentation function given by the parameterizations or model calculations. With the foundation of the transverse-momentum-dependent factorization, the QCD evolution of leading twist transverse-momentum-dependent fragmentation functions has also been established. In addition, the universality of fragmentation functions has been proven, albeit model-dependently, so that it is possible to perform a global analysis of experimental data in different high-energy reactions. The collective efforts may eventually reveal important information hidden in the shadow of nonperturbative physics. This review covers the following topics: transverse-momentum-dependent factorization and the corresponding QCD evolution, spin-dependent fragmentation functions at leading and higher twists, several experimental measurements and corresponding phenomenological studies, and some model calculations.
Citation: Particles
PubDate: 2023-04-27
DOI: 10.3390/particles6020029
Issue No: Vol. 6, No. 2 (2023)
- Particles, Vol. 6, Pages 546-555: Probing the Hot QCD Matter via Quarkonia
at the Next-Generation Heavy-Ion Experiment at LHC
Authors: Yuri Kharlov, Yeghishe Hambardzumyan, Antony Varlamov
First page: 546
Abstract: Quarkonia represent one of the most valuable probes of the deconfined quark–gluon hot medium since the very first experimental studies with ultrarelativistic heavy-ion collisions. A significant step forward in characterizing the QCD matter via systematic studies of quarkonia production will be performed by the next-generation heavy-ion experiment ALICE 3, a successor of the ongoing ALICE experiment at the Large Hadron Collider. The new advanced detector of ALICE 3 will allow for exploring the production of S- and P-state quarkonia at high statistics, at low and moderate transverse momenta ranges. The performance of ALICE 3 for quarkonia measurements and the requirements for the detectors are discussed.
Citation: Particles
PubDate: 2023-05-02
DOI: 10.3390/particles6020030
Issue No: Vol. 6, No. 2 (2023)
- Particles, Vol. 6, Pages 556-567: The van der Waals Hexaquark Chemical
Potential in Dense Stellar Matter
Authors: Keith Andrew, Eric V. Steinfelds, Kristopher A. Andrew
First page: 556
Abstract: We explore the chemical potential of a QCD-motivated van der Waals (VDW) phase change model for the six-quark color-singlet, strangeness S = −2 particle known as the hexaquark with quark content (uuddss). The hexaquark may have internal structure, indicated by short range correlations that allow for non-color-singlet diquark and triquark configurations whose interactions will change the magnitude of the chemical potential. In the multicomponent VDW Equation of State (EoS), the quark-quark particle interaction terms are sensitive to the QCD color factor, causing the pairing of these terms to give different interaction strengths for their respective contributions to the chemical potential. This results in a critical temperature near 163 MeV for the color-singlet states and tens of MeV below this for various mixed diquark and triquark states. The VDW chemical potential is also sensitive to the number density, leading to chemical potential isotherms that exhibit spinodal extrema, which also depend upon the internal hexaquark configurations. These extrema determine regions of metastability for the mixed states near the critical point. We use this chemical potential with the chemical potential-modified TOV equations to investigate the properties of hexaquark formation in cold compact stellar cores in beta equilibrium. We find thresholds for hexaquark layers and changes in maximum mass values that are consistent with observations from high mass compact stellar objects such as PSR 09043 + 10 and GW 190814. In general, we find that the VDW-TOV model has an upper stability mass and radius bound for a chemical potential of 1340 MeV with a compactness of C~0.2.
Citation: Particles
PubDate: 2023-05-09
DOI: 10.3390/particles6020031
Issue No: Vol. 6, No. 2 (2023)
- Particles, Vol. 6, Pages 568-579: Centrality Determination in Heavy-Ion
Collisions Based on Monte-Carlo Sampling of Spectator Fragments
Authors: Ilya Segal
First page: 568
Abstract: The size and evolution of the matter created in a relativistic heavy-ion collision strongly depend on collision geometry, defined by centrality. Experimentally the centrality of collisions can be characterized by the measured multiplicities of the produced particles at midrapidity or by the energy measured in the forward rapidity region, which is sensitive to the spectator fragments. This serves as a proxy for the true collision centrality, as defined by the impact parameter in the models of collisions. In this work, the procedure for centrality determination based on Monte-Carlo sampling of spectator fragments has been proposed. The validity of the procedure has been checked using the fully reconstructed DCM-QGSM-SMM model events and published data from the NA61/SHINE experiment.
Citation: Particles
PubDate: 2023-05-10
DOI: 10.3390/particles6020032
Issue No: Vol. 6, No. 2 (2023)
- Particles, Vol. 6, Pages 580-594: Mechanisms of Producing Primordial Black
Holes and Their Evolution
Authors: Maxim A. Krasnov, Valery V. Nikulin
First page: 580
Abstract: Primordial black holes have become a highly intriguing and captivating field of study in cosmology due to their potential theoretical and observational significance. This review delves into a variety of mechanisms that could give rise to PBHs and explores various methods for examining their evolution through mass accretion.
Citation: Particles
PubDate: 2023-05-14
DOI: 10.3390/particles6020033
Issue No: Vol. 6, No. 2 (2023)
- Particles, Vol. 6, Pages 595-610: Parameters and Pulsation Constant of
Cepheid
Authors: Sergei V. Sinitsyn
First page: 595
Abstract: The analysis of fifty empirical period-radius relations and forty-three empirical period-luminosity relations is performed for the Cepheids. It is found that most of these relations have significant systematic errors. A new metrological method is suggested to exclude these systematic errors using the new empirical metrological relations and the empirical temperature scale of the various samples of the Cepheids. In this regard, the reliable relations between the mass, radius, effective surface temperature, luminosity, absolute magnitude on the one hand, and the pulsation period on the other hand, as well as the reliable dependence of the radius on the mass are determined for the Cepheids of types δ Cephei and δ Scuti from the Galaxy. These reliable relations permit us to accurately determine the empirical value of the pulsation constant for the Cepheids of both types for the first time. It is found that the pulsation constant very weakly depends on the pulsation period of the Cepheid, contrary to the known theoretical calculation. Hence, the Cepheids pulsate almost as a unified whole and homogeneous spherical body in wide ranges of a star’s mass and evolutionary state with an extremely inhomogeneous distribution of stellar substance over its volume. Therefore, it is first suggested that the pulsation of the Cepheid is, first of all, the pulsation of the almost unified whole and homogenous shell of its gravitational mass. This pulsation is triggered by well-known effects; for example, the local optical opacity of the stellar substance and overshooting, using the usual pulsation of the stellar substance.
Citation: Particles
PubDate: 2023-05-26
DOI: 10.3390/particles6020034
Issue No: Vol. 6, No. 2 (2023)
- Particles, Vol. 6, Pages 611-621: Testing the Paradigm of Nuclear
Many-Body Theory
Authors: Omar Benhar
First page: 611
Abstract: Nuclear many-body theory is based on the tenet that nuclear systems can be accurately described as collections of point-like particles. This picture, while providing a remarkably accurate explanation of a wealth of measured properties of atomic nuclei, is bound to break down in the high-density regime, in which degrees of freedom other than protons and neutrons are expected to come into play. Valuable information on the validity of the description of dense nuclear matter in terms of nucleons, needed to firmly establish its limit of applicability, can be obtained from electron–nucleus scattering data at large momentum transfer and low energy transfer. The emergence of y-scaling in this kinematic region, unambiguously showing that the beam particles couple to high-momentum nucleons belonging to strongly correlated pairs, indicates that at densities as large as five times nuclear density—typical of the neutron star interior—nuclear matter largely behaves as a collection of nucleons.
Citation: Particles
PubDate: 2023-05-31
DOI: 10.3390/particles6020035
Issue No: Vol. 6, No. 2 (2023)
- Particles, Vol. 6, Pages 622-637: Toward the System Size Dependence of
Anisotropic Flow in Heavy-Ion Collisions at sNN = 2–5GeV
Authors: Mikhail Mamaev, Arkadiy Taranenko
First page: 622
Abstract: The study of the high-density equation of state (EOS) and the search for a possible phase transition in dense baryonic matter is the main goal of beam energy scan programs with relativistic heavy ions at energies sNN= 2–5 GeV. The most stringent constraints currently available on the high-density EOS of symmetric nuclear matter come from the present measurements of directed (v1) and elliptic flow (v2) signals of protons in Au + Au collisions. In this energy range, the anisotropic flow is strongly affected by the presence of cold spectators due to the sizable passage time. The system size dependence of anisotropic flow may help to study the participant–spectator contribution and improve our knowledge of the EOS of symmetric nuclear matter. In this work, we discuss the layout of the upgraded BM@N experiment and the anticipated performance for differential anisotropic flow measurements of identified hadrons at Nuclotron energies: sNN= 2.3–3.5 GeV.
Citation: Particles
PubDate: 2023-06-02
DOI: 10.3390/particles6020036
Issue No: Vol. 6, No. 2 (2023)
- Particles, Vol. 6, Pages 638-646: The Particle-Tracking Simulation of a
New Photocathode RF Gun in the Free-Electron Laser Facility, KU-FEL
Authors: Yuhao Zhao, Heishun Zen, Hideaki Ohgaki
First page: 638
Abstract: A project is underway that aims to generate attosecond pulses via high-harmonic generation in rare gases, driven by extremely short and highly intense pulses from free-electron-laser oscillators. For this purpose, it has been planned that a new photocathode RF gun, dedicated to high-bunch-charge operation, will be installed at the KU-FEL (Kyoto University Free Electron Laser) oscillator facility. In this study, RF guns with two different structures (1.6-cell and 1.4-cell) were compared, from the perspective of exploring the possibility of introducing bunch-interval modulation, which is important for achieving high extraction efficiency in the FEL oscillator. As a result, it was confirmed that the introduction of bunch-phase modulation would be possible only in the case of the 1.6-cell RF gun. After the structure of the RF gun was decided on, particle-tracking simulations were performed, to study the electron-beam parameters using the 1.6-cell RF gun and 1 nC bunch charge. The results showed that we could obtain the peak current of 1 kA without a large degradation of the other parameters.
Citation: Particles
PubDate: 2023-06-06
DOI: 10.3390/particles6020037
Issue No: Vol. 6, No. 2 (2023)
- Particles, Vol. 6, Pages 647-663: Density and Mass Function for Regular
Rotating Electrically Charged Compact Objects Determined by Nonlinear
Electrodynamics Minimally Coupled to Gravity
Authors: Irina Dymnikova
First page: 647
Abstract: We address the question of the electromagneticdensity and the mass function for regular rotating electrically charged compact objects as determined by dynamical equations of nonlinear electrodynamics minimally coupled to gravity. The rotating electrically charged compact objects are described by axially symmetric geometry, in which their electromagnetic fields are governed by four source-free equations for two independent field components of the electromagnetic tensor Fμν, with two constraints on the integration functions. An additional condition of compatibility of four dynamical equations for two independent field functions imposes the constraint on the Lagrange derivative LF=dL/dF, directly related to the electromagnetic density. As a result, the compatibility condition determines uniquely the generic form of the electromagnetic density and the mass function for regular rotating electrically charged compact objects.
Citation: Particles
PubDate: 2023-06-06
DOI: 10.3390/particles6020038
Issue No: Vol. 6, No. 2 (2023)
- Particles, Vol. 6, Pages 664-673: Development of Type A Quadrupole Magnet
for Siam Photon Source II
Authors: Supachai Prawanta, Thongchai Leetha, Pariwat Singthong, Pajeeraphorn Numanoy, Apichai Kwankasem, Visitchai Sooksrimuang, Chaiyut Preecha, Supat Klinkiew, Prapaiwan Sunwong
First page: 664
Abstract: A prototype of a type A quadrupole magnet has been designed and manufactured for the 3 GeV storage ring of Siam Photon Source II, the second synchrotron light source in Thailand. The required quadrupole gradient is 51 T/m with the magnet effective length being 162 mm. Magnet modeling and magnetic field calculation were performed using Radia and Opera-3D. The bore radius of the magnet is 16 mm. The magnet will be operated at the excitation of 5544 A-turns. A mechanical analysis of the magnet structure was performed in SOLIDWORKS and ANSYS, where the maximum deformation of 0.003 mm was found at the magnet poles, and the first-mode natural frequency was higher than 100 Hz. The magnet yoke is made of AISI 1006 low-carbon steel with a fabrication tolerance of ±0.020 mm. Magnet coils are water-cooled and made of high-purity copper. The temperature rise of the coils was below 3.0 °C at the maximum excitation of 6664 A-turns, which is 20% above the operating point. Magnetic field measurement was carried out using the Hall probe technique. The measured magnetic field and coil temperature of the prototype show good agreement with the calculations.
Citation: Particles
PubDate: 2023-06-09
DOI: 10.3390/particles6020039
Issue No: Vol. 6, No. 2 (2023)
- Particles, Vol. 6, Pages 674-681: Design and Beam Dynamic Studies of an
Injector for a Compact THz Coherent Radiation Source
Authors: Siriwan Jummunt, Wanisa Promdee, Thakonwat Chanwattana, Nawin Junthong, Somjai Chunjarean, Supat Klinkhieo
First page: 674
Abstract: An intense narrow-band terahertz (THz) radiation source has been designed to generate a broad tuning range of radiation frequencies between 0.5 THz and 5.0 THz. The THz radiation is produced when a short-bunch electron beam propagates through an undulator. To achieve high-power peak radiation, the source requires high-brightness electron beams with low beam emittance and short bunch length. A proposed design for the photocathode RF gun used as the electron source is presented. The gun with high mode separation and high Q-factor can be achieved for producing a good beam quality. The beam dynamics of the injector have been preliminarily optimized using the software ASTRA and Elegant, investigating the impact of laser pulse shape on electron beam quality. The results of the beam dynamics studies are comprehensively discussed in this paper.
Citation: Particles
PubDate: 2023-06-16
DOI: 10.3390/particles6020040
Issue No: Vol. 6, No. 2 (2023)
- Particles, Vol. 6, Pages 30-56: Constraints on Nuclear Symmetry Energy
Parameters
Authors: James M. Lattimer
First page: 30
Abstract: A review is made of constraints on the nuclear symmetry energy parameters arising from nuclear binding energy measurements, theoretical chiral effective field predictions of neutron matter properties, the unitary gas conjecture, and measurements of neutron skin thicknesses and dipole polarizabilities. While most studies have been confined to the parameters SV and L, the important roles played by, and constraints on Ksym, or, equivalently, the neutron matter incompressibility KN, are discussed. Strong correlations among SV,L, and KN are found from both nuclear binding energies and neutron matter theory. However, these correlations somewhat differ in the two cases, and those from neutron matter theory have smaller uncertainties. To 68% confidence, it is found from neutron matter theory that SV=32.0±1.1 MeV, L=51.9±7.9 MeV and KN=152.2±38.1 MeV. Theoretical predictions for neutron skin thickness and dipole polarizability measurements of the neutron-rich nuclei 48Ca, 120Sn, and 208Pb are compared to recent experimental measurements, most notably the CREX and PREX neutron skin experiments from Jefferson Laboratory. By themselves, PREX I+II measurements of 208Pb and CREX measurement of 48Ca suggest L=121±47 MeV and L=−5±40 MeV, respectively, to 68% confidence. However, we show that nuclear interactions optimally satisfying both measurements imply L=53±13 MeV, nearly the range suggested by either nuclear mass measurements or neutron matter theory, and is also consistent with nuclear dipole polarizability measurements. This small parameter range implies R1.4=11.6±1.0 km and Λ1.4=228−90+148, which are consistent with NICER X-ray and LIGO/Virgo gravitational wave observations of neutron stars.
Citation: Particles
PubDate: 2023-01-04
DOI: 10.3390/particles6010003
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 57-120: Emergence of Hadron Mass and Structure
Authors: Minghui Ding, Craig D. Roberts, Sebastian M. Schmidt
First page: 57
Abstract: Visible matter is characterised by a single mass scale; namely, the proton mass. The proton’s existence and structure are supposed to be described by quantum chromodynamics (QCD); yet, absent Higgs boson couplings, chromodynamics is scale-invariant. Thus, if the Standard Model is truly a part of the theory of Nature, then the proton mass is an emergent feature of QCD; and emergent hadron mass (EHM) must provide the basic link between theory and observation. Nonperturbative tools are necessary if such connections are to be made; and in this context, we sketch recent progress in the application of continuum Schwinger function methods to an array of related problems in hadron and particle physics. Special emphasis is given to the three pillars of EHM—namely, the running gluon mass, process-independent effective charge, and running quark mass; their role in stabilising QCD; and their measurable expressions in a diverse array of observables.
Citation: Particles
PubDate: 2023-01-11
DOI: 10.3390/particles6010004
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 121-133: Interference with Non-Interacting Free
Particles and a Special Type of Detector
Authors: Ioannis Contopoulos, Athanasios C. Tzemos, Foivos Zanias, George Contopoulos
First page: 121
Abstract: This paper demonstrates how a classical detector that collects non-interacting individual classical massive free particles can generate a quantum interference pattern. The proposed classical picture requires that particles carry the information of a phase equal to an action integral along their trajectory. At the point of their detection, a special type of detector collects the phases from all individual particles reaching it, adds them up over time as complex numbers, and divides them by the square root of their number. The detector announces a number of detections equal to the square of the amplitude of the resulting complex number. An interference pattern is gradually built from the collection of particle phases in the detection bins of the detector after several repetitions of the experiment. We obtain perfect agreement with three solutions of the Schrödinger equation for free particles: a Gaussian wavepacket, two Gaussian wavepackets approaching each other, and a Gaussian wavepacket reflecting off a wall. The main conclusion of the present work is that the interference of quantum mechanics is basically due to the detectors that collect the particles when there are macroscopic detectors operating as proposed. Finally, a simple physical experiment with a single-photon detector is proposed that will be able to test our theory.
Citation: Particles
PubDate: 2023-01-17
DOI: 10.3390/particles6010005
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 134-135: Acknowledgment to the Reviewers of
Particles in 2022
Authors: Particles Editorial Office Particles Editorial Office
First page: 134
Abstract: High-quality academic publishing is built on rigorous peer review [...]
Citation: Particles
PubDate: 2023-01-18
DOI: 10.3390/particles6010006
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 136-143: Coulomb Force from Non-Local
Self-Assembly of Multi-Peak Densities in a Charged Space Continuum
Authors: Igor É. Bulyzhenkov
First page: 136
Abstract: Maxwell’s electrodynamics admits radial charge densities of the elementary organization with one vertex of the spherical symmetry. A multi-vertex distribution of sharply inhomogeneous charge densities can also be described by monistic field solutions to Maxwell’s equations–equalities. Coulomb–Lorentz forces are exerted locally to correlated electric densities in their volume organization with the fixed self-energy integral. The long-range Coulomb interaction between the dense peaks of the charged space continuum can be described quantitatively through bulk integrals of local tensions within observable bodies in favor of the monistic all-unity in the material space physics of Descartes and Russian cosmists.
Citation: Particles
PubDate: 2023-01-20
DOI: 10.3390/particles6010007
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 144-172: Beyond the Standard Model with
Six-Dimensional Spinors
Authors: David Chester, Alessio Marrani, Michael Rios
First page: 144
Abstract: Six-dimensional spinors with Spin(3,3) symmetry are utilized to efficiently encode three generations of matter. E8(−24) is shown to contain physically relevant subgroups with representations for GUT groups, spacetime symmetries, three generations of the standard model fermions, and Higgs bosons. Pati–Salam, SU(5), and Spin(10) grand unified theories are found when a single generation is isolated. For spacetime symmetries, Spin(4,2) may be used for conformal symmetry, AdS5→dS4, or simply broken to Spin(3,1) of a Minkowski space. Another class of representations finds Spin(2,2) and can give AdS3 with various GUTs. An action for three generations of fermions in the Majorana–Weyl spinor 128 of Spin(4,12) is found with Spin(3) flavor symmetry inside E8(−24). The 128 of Spin(12,4) can be regarded as the tangent space to a particular pseudo-Riemannian form of the octo-octonionic Rosenfeld projective plane E8(−24)/Spin(12,4)=(OsxO)P2.
Citation: Particles
PubDate: 2023-01-28
DOI: 10.3390/particles6010008
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 173-187: Direct Photon Production in Heavy-Ion
Collisions: Theory and Experiment
Authors: Dmitry Blau, Dmitri Peresunko
First page: 173
Abstract: Direct photons provide a possibility to test properties of hot matter created in proton–proton (pp), proton–nucleus (p–A) or nucleus–nucleus (A–A) collisions. As they are created in charged particles’ scatterings and freely escape the hot region, they provide a tool to test all stages of the collision: the scattering of the partons of incoming nucleons, pre-equilibrium evolution and collective expansion of hot quark–gluon matter created in nucleus–nucleus collisions. Comparing direct photon production in pp, p–A and A–A collisions, one can check the scaling with the number of binary collisions expected at a high transverse momentum range and obtain insight into the hot and cold hadronic matter properties with soft photons. The collective elliptic flow of direct photons is a unique possibility to trace the collective flow formation and space–time evolution of the fireball. We review the experimental results on direct photon production in pp, p–A and A–A collisions at the Super Proton Synchroton (SPS), the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) energies and discuss an agreement of theoretical predictions with measurements. Finally, we present predictions of direct photon spectra and collective flow for lower energy collisions expected at the Nuclotron-based Ion Collider fAcility (NICA) and the Facility for Antiproton and Ion Research (FAIR).
Citation: Particles
PubDate: 2023-01-30
DOI: 10.3390/particles6010009
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 188-197: Charge Asymmetry of Muons Generated in a
Muon Generator from Ultra-Dense Hydrogen D(0) and p(0)
Authors: Holmlid
First page: 188
Abstract: Laser-induced nuclear reactions in ultra-dense hydrogen H(0) (review in Physica Scripta 2019) create mesons (kaons and pions). These mesons decay mainly to muons. The muons created are useful (patented source) for the muon-induced fusion process. The sign of the muons from the source depends on the initial baryons used. With D(0) (ultra-dense deuterium) the source produces mainly positive muons and with p(0) (ultra-dense protium) the source produces mainly negative muons. Negative muons are required for muon-induced fusion. This charge asymmetry was reported earlier, and has now been confirmed by experiments with a coil current transformer as the beam detector. The current coil detector would give no signal from the muons if charge symmetry existed. The charge asymmetry could indicate unknown processes, for example, caused by the different annihilation processes in D(0) and p(0). The conclusions of a new analysis of the results are presented here. Using D(0) in the muon source, the asymmetry is likely due to the capture of µ- in D atoms and D2 molecules. This leads to emission of excess µ+ from D(0). With p(0) in the muon source, the capture rate of µ- is lower than in D(0). The emitted number of µ+ will be decreased by the reaction between µ+ and the surrounding abundant electrons, forming neutral muonium particles. This effect decreases the amount of emitted µ+ for both p(0) and D(0), and it is proposed to be the main reason for a larger fraction of emitted µ- in the case of p(0). Thus, there is no dominant emission of negative muons which would violate charge conservation.
Citation: Particles
PubDate: 2023-01-30
DOI: 10.3390/particles6010010
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 198-216: Bayesian Exploration of Phenomenological
EoS of Neutron/Hybrid Stars with Recent Observations
Authors: Emanuel V. Chimanski, Ronaldo V. Lobato, Andre R. Goncalves, Carlos A. Bertulani
First page: 198
Abstract: The description of the stellar interior of compact stars remains as a big challenge for the nuclear astrophysics community. The consolidated knowledge is restricted to density regions around the saturation of hadronic matter ρ0=2.8×1014gcm−3, regimes where our nuclear models are successfully applied. As one moves towards higher densities and extreme conditions up to the quark/gluons deconfinement, little can be said about the microphysics of the equation of state (EoS). Here, we employ a Markov Chain Monte Carlo (MCMC) strategy to access the variability at high density regions of polytropic piecewise models for neutron star (NS) EoS or possible hybrid stars, i.e., a NS with a small quark-matter core. With a fixed description of the hadronic matter for low density, below the nuclear saturation density, we explore a variety of models for the high density regimes leading to stellar masses near to 2.5M⊙, in accordance with the observations of massive pulsars. The models are constrained, including the observation of the merger of neutrons stars from VIRGO-LIGO and with the pulsar observed by NICER. In addition, we also discuss the possibility of the use of a Bayesian power regression model with heteroscedastic error. The set of EoS from the Laser Interferometer Gravitational-Wave Observatory (LIGO) was used as input and treated as the data set for the testing case.
Citation: Particles
PubDate: 2023-02-02
DOI: 10.3390/particles6010011
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 217-238: Masses of Compact (Neutron) Stars with
Distinguished Cores
Authors: Rico Zöllner, Minghui Ding, Burkhard Kämpfer
First page: 217
Abstract: In this paper, the impact of core mass on the compact/neutron-star mass-radius relation is studied. Besides the mass, the core is parameterized by its radius and surface pressure, which supports the outside one-component Standard Model (SM) matter. The core may accommodate SM matter with unspecified (or poorly known) equation-of-state or several components, e.g., consisting of admixtures of Dark Matter and/or Mirror World matter etc. beyond the SM. Thus, the admissible range of masses and radii of compact stars can be considerably extended.
Citation: Particles
PubDate: 2023-02-02
DOI: 10.3390/particles6010012
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 239-244: The Invariance of Inelastic Overlap
Function
Authors: Sergey Mikhailovich Troshin, Nikolai Evgenjevich Tyurin
First page: 239
Abstract: In this study, we consider the symmetry property of the inelastic overlap function and its relation to the reflective scattering mode appearance. This symmetry property disfavors an exclusion of one of the scattering modes—the reflective mode—when approaching the asymptotic limit. Predominance of the particular mode correlates with the energy and impact parameters ranges.
Citation: Particles
PubDate: 2023-02-03
DOI: 10.3390/particles6010013
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 245-261: Λ Polarization and Vortex Rings
in Heavy-Ion Collisions at NICA Energies
Authors: Yuri B. Ivanov, Alexei A. Soldatov
First page: 245
Abstract: We review recent studies of vortical motion and the resulting polarization of Λ hyperons in heavy-ion collisions at NICA energies, in particular, within the model of three-fluid dynamics (3FD). This includes predictions of the global Λ polarization and ring structures that appear in Au+Au collisions. The global Λ polarization in Au+Au collisions is calculated, including its rapidity and centrality dependence. The contributions of the thermal vorticity and meson-field term (proposed by Csernai, Kapusta, and Welle) to the global polarization are considered. The results are compared with data from recent STAR and HADES experiments. It is predicted that the polarization maximum is reached at sNN≈ 3 GeV if the measurements are performed with the same acceptance. It is demonstrated that a pair of vortex rings are formed, one at forward rapidities and another at backward rapidities, in ultra-central Au+Au collisions at sNN> 4 GeV. The vortex rings carry information about the early stage of the collision, in particular, the stopping of baryons. It is shown that these rings can be detected by measuring the ring observable RΛ, even in the midrapidity region at sNN= 5–20 GeV. At forward/backward rapidities, the RΛ signal is expected to be stronger. The possibility of observing the vortex-ring signal against the background of non-collective transverse polarization is discussed.
Citation: Particles
PubDate: 2023-02-06
DOI: 10.3390/particles6010014
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 262-296: Generalised Parton Distributions in
Continuum Schwinger Methods: Progresses, Opportunities and Challenges
Authors: Cédric Mezrag
First page: 262
Abstract: This paper review the modelling efforts regarding Generalised Parton Distributions (GPDs) using continuum techniques relying on Dyson–Schwinger and Bethe–Salpeter equations. The definition and main properties of the GPDs are first recalled. Then, we detail the strategies developed in the last decade in the meson sector, highlighting that observables connected to the pion GPDs may be measured at future colliders. We also highlight the challenges one will face when targeting baryons in the future.
Citation: Particles
PubDate: 2023-02-08
DOI: 10.3390/particles6010015
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 297-311: Long-Lived Particles Anomaly Detection
with Parametrized Quantum Circuits
Authors: Simone Bordoni, Denis Stanev, Tommaso Santantonio, Stefano Giagu
First page: 297
Abstract: We investigate the possibility to apply quantum machine learning techniques for data analysis, with particular regard to an interesting use-case in high-energy physics. We propose an anomaly detection algorithm based on a parametrized quantum circuit. This algorithm was trained on a classical computer and tested with simulations as well as on real quantum hardware. Tests on NISQ devices were performed with IBM quantum computers. For the execution on quantum hardware, specific hardware-driven adaptations were devised and implemented. The quantum anomaly detection algorithm was able to detect simple anomalies such as different characters in handwritten digits as well as more complex structures such as anomalous patterns in the particle detectors produced by the decay products of long-lived particles produced at a collider experiment. For the high-energy physics application, the performance was estimated in simulation only, as the quantum circuit was not simple enough to be executed on the available quantum hardware platform. This work demonstrates that it is possible to perform anomaly detection with quantum algorithms; however, as an amplitude encoding of classical data is required for the task, due to the noise level in the available quantum hardware platform, the current implementation cannot outperform classic anomaly detection algorithms based on deep neural networks.
Citation: Particles
PubDate: 2023-02-13
DOI: 10.3390/particles6010016
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 312-363: Gauge Sector Dynamics in QCD
Authors: Mauricio Narciso Ferreira, Joannis Papavassiliou
First page: 312
Abstract: The dynamics of the QCD gauge sector give rise to non-perturbative phenomena that are crucial for the internal consistency of the theory; most notably, they account for the generation of a gluon mass through the action of the Schwinger mechanism, the taming of the Landau pole, the ensuing stabilization of the gauge coupling, and the infrared suppression of the three-gluon vertex. In the present work, we review some key advances in the ongoing investigation of this sector within the framework of the continuum Schwinger function methods, supplemented by results obtained from lattice simulations.
Citation: Particles
PubDate: 2023-02-15
DOI: 10.3390/particles6010017
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 364-372: Feasibility Studies for the Measurement
of Open-Charm Mesons at ALICE-3 Using Decay Channels with Neutral Mesons
and Photons in the Final State
Authors: Mikhail Malaev, Victor Riabov
First page: 364
Abstract: ALICE-3 is being designed as a next-generation heavy-ion experiment to be operated at the high-luminosity Large Hadron Collider. With luminosities higher by a factor of fifty, ALICE-3 will be able to study5 properties of quark–gluon matter with probes and precision which were previously unavailable due to small cross sections, high background levels, and insufficient detector sensitivity. In particular, the properties of hot and dense QCD matter will be studied by measuring production cross sections, flow coefficients, azimuthal angular correlations and nuclear modification factors for open-charm hadrons. In this contribution, we present the results of feasibility studies for the measurement of ground and excited states of open-charm mesons in decay channels D0 → K− + π+ + π0, D*(2007)0 → D0 + γ and D*(2010)± → D0 + π± in pp, p-Pb and Pb-Pb collisions at LHC energies using the ALICE-3 experimental setup. We formulate the main requirements for the selection of particles and their combinations to ensure reliable signal extraction in a wide transverse momentum range and estimate the minimum size of the required data samples. The results obtained are also compared to previous findings for the open-charm measurements in different decay channels.
Citation: Particles
PubDate: 2023-02-17
DOI: 10.3390/particles6010018
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 373-384: Λ and Λ¯ Freeze-Out
Distributions and Global Polarizations in Au+Au Collisions
Authors: Nikita Tsegelnik, Evgeni Kolomeitsev, Vadym Voronyuk
First page: 373
Abstract: The gold–gold collisions at sNN=7.7 and 11.5 GeV are simulated within the PHSD transport model. In each collision event, the spectator nucleons are separated and the fluidization procedure for the participants is performed. The local velocities are determined in the Landau frame and the kinematic and thermal vorticity fields are evaluated. We analyze the thermodynamic properties of the cells where Λs and Λ¯s were born or had their last interaction. Such cells contribute to the formation of the observed global polarization of hyperons induced by the thermal vorticity of the medium. The Λ¯ polarization signal is found to be mainly determined by hot, dense, and highly vortical cells at the earlier stage of the collision, whereas the Λ polarization signal is accumulated over the longer time and includes cells with lower vorticity. The calculated global polarizations for both Λs and Λ¯s agree well with the experimental finding by the STAR collaboration at energy sNN=11.5 GeV. For collisions at sNN=7.7 GeV, we can reproduce the STAR data for Λ hyperons, but significantly underpredict the observed global polarization of Λ¯. Furthermore, we consider the centrality dependence of the hyperon polarization in collisions at 7.7 GeV. It increases with an increase of centrality, reaches a maximum at 65–75% and then starts decreasing rapidly for peripheral collisions.
Citation: Particles
PubDate: 2023-02-27
DOI: 10.3390/particles6010019
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 385-398: Precision Storage Rings for Electric
Dipole Moment Searches: A Tool En Route to Physics
Beyond-the-Standard-Model
Authors: Hans Ströher, Sebastian M. Schmidt, Paolo Lenisa, Jörg Pretz
First page: 385
Abstract: Electric Dipole Moments (EDM) of particles (leptons, nucleons, and light nuclei) are currently deemed one of the best indicators for new physics, i.e., phenomena which lie outside the Standard Model (SM) of elementary particle physics—so-called physics “Beyond-the-Standard-Model” (BSM). Since EDMs of the SM are vanishingly small, a finite permanent EDM would indicate charge-parity (CP) symmetry violation in addition to the well-known sources of the SM, and could explain the baryon asymmetry of the Universe, while an oscillating EDM would hint at a possible Dark Matter (DM) field comprising axions or axion-like particles (ALPs). A new approach exploiting polarized charged particles (proton, deuteron, 3He) in precision storage rings offers the prospect to push current experimental EDM upper limits significantly further, including the possibility of an EDM discovery. In this paper, we describe the scientific background and the steps towards the realization of a precision storage ring, which will make such measurements possible.
Citation: Particles
PubDate: 2023-03-02
DOI: 10.3390/particles6010020
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 399-404: Prospects for the (Hyper)Nuclei Study in
the Nica Energy Range
Authors: Viktar Kireyeu, Vadim Kolesnikov, Alexander Zinchenko, Veronika Vasendina, Alexander Mudrokh
First page: 399
Abstract: The production of nuclei and hypernuclei is of interest for experimental and theoretical studies: it is a big question how such weakly bound objects survive in a hot, dense environment and which new insights on the heavy-ion collisions dynamics they can bring us. We present the results on the hypernuclei feasibility study for the flagship Nuclotron-based Ion Collider fAcility (NICA)/Multi-Purpose Detector (MPD) experiment at the Joint Institute for Nuclear Research (JINR) in Dubna using the Parton-Hadron-Quantum-Molecular Dynamics (PHQMD) transport approach and a realistic reconstruction chain.
Citation: Particles
PubDate: 2023-03-02
DOI: 10.3390/particles6010021
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 405-415: An Improved Core-Corona Model for
Λ and Λ Polarization in Relativistic Heavy-Ion Collisions
Authors: Alejandro Ayala, Isabel Dominguez, Ivonne Maldonado, Maria Elena Tejeda-Yeomans
First page: 405
Abstract: Due to its sensitivity to the dynamics of strongly interacting matter subject to extreme conditions, hyperon global polarization has become an important observable to study the system created in relativistic heavy-ion collisions. Recently, the STAR and HADES collaborations have measured the global polarization of both Λ and Λ¯ produced in semi-central collisions in a wide range of collision energies. The polarization excitation functions show an increasing trend as the collision energy decreases, with the increase being more pronounced for the Λ¯. In this work, we make a summary of a core-corona model that we have developed to quantify the global polarization contributions from Λ and Λ¯ created in different regions of the fireball. The core-corona model assumes that Λs and Λ¯s are produced in both regions, the high-density core and the lower density corona, with different relative abundances which modulate the polarization excitation function. We have shown that the model works well for the description of experimental results. The global polarization excitation functions computed with the model show a peak at different collision energies in the region sNN≤10 GeV. Finally, we discuss and report on the model global polarization predictions for BES-II, NICA and CBM at FAIR and HADES energies.
Citation: Particles
PubDate: 2023-03-03
DOI: 10.3390/particles6010022
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 416-439: Nucleon Resonance Electroexcitation
Amplitudes and Emergent Hadron Mass
Authors: Daniel S. Carman, Ralf W. Gothe, Victor I. Mokeev, Craig D. Roberts
First page: 416
Abstract: Understanding the strong interaction dynamics that govern the emergence of hadron mass (EHM) represents a challenging open problem in the Standard Model. In this paper we describe new opportunities for gaining insight into EHM from results on nucleon resonance (N*) electroexcitation amplitudes (i.e., γvpN* electrocouplings) in the mass range up to 1.8 GeV for virtual photon four-momentum squared (i.e., photon virtualities Q2) up to 7.5 GeV2 available from exclusive meson electroproduction data acquired during the 6-GeV era of experiments at Jefferson Laboratory (JLab). These results, combined with achievements in the use of continuum Schwinger function methods (CSMs), offer new opportunities for charting the momentum dependence of the dressed quark mass from results on the Q2-evolution of the γvpN* electrocouplings. This mass function is one of the three pillars of EHM and its behavior expresses influences of the other two, viz. the running gluon mass and momentum-dependent effective charge. A successful description of the Δ(1232)3/2+ and N(1440)1/2+ electrocouplings has been achieved using CSMs with, in both cases, common momentum-dependent mass functions for the dressed quarks, for the gluons, and the same momentum-dependent strong coupling. The properties of these functions have been inferred from nonperturbative studies of QCD and confirmed, e.g., in the description of nucleon and pion elastic electromagnetic form factors. Parameter-free CSM predictions for the electrocouplings of the Δ(1600)3/2+ became available in 2019. The experimental results obtained in the first half of 2022 have confirmed the CSM predictions. We also discuss prospects for these studies during the 12-GeV era at JLab using the CLAS12 detector, with experiments that are currently in progress, and canvass the physics motivation for continued studies in this area with a possible increase of the JLab electron beam energy up to 22 GeV. Such an upgrade would finally enable mapping of the dressed quark mass over the full range of distances (i.e., quark momenta) where the dominant part of hadron mass and N* structure emerge in the transition from the strongly coupled to perturbative QCD regimes.
Citation: Particles
PubDate: 2023-03-15
DOI: 10.3390/particles6010023
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 440-450: Light-Nuclei Production in Heavy-Ion
Collisions at sNN = 6.4 – 19.6 GeV in THESEUS Generator Based on
Three-Fluid Dynamics
Authors: Marina Kozhevnikova, Yuri B. Ivanov
First page: 440
Abstract: Light-nuclei production in relativistic heavy-ion collisions is simulated within an updated Three-fluid Hydrodynamics-based Event Simulator Extended by UrQMD (Ultra-relativistic Quantum Molecular Dynamics) final State interactions (THESEUS). The simulations are performed in the collision energy range of sNN= 6.4–19.6 GeV. The light-nuclei are produced within the thermodynamical approach on an equal basis with hadrons. Since the light nuclei do not participate in the UrQMD evolution, the only additional parameter related to the light nuclei, i.e., the energy density of late freeze-out, is used for the imitation of the afterburner stage of the collision. The updated THESEUS provides a reasonable reproduction of data on bulk observables of the light nuclei, especially their functional dependence on the collision energy and light-nucleus mass. Various ratios, d/p, t/p, t/d, and N(t)×N(p)/N2(d), are also considered. Imperfect reproduction of the light-nuclei data leaves room for medium effects in produced light nuclei.
Citation: Particles
PubDate: 2023-03-16
DOI: 10.3390/particles6010024
Issue No: Vol. 6, No. 1 (2023)
- Particles, Vol. 6, Pages 451-469: Future of Neutron Star Studies with Fast
Radio Bursts
Authors: Sergei B. Popov, Maxim S. Pshirkov
First page: 451
Abstract: Fast radio bursts (FRBs) were discovered only in 2007. However, the number of known events and sources of repeating bursts grows very rapidly. In the near future, the number of events will be ≳104 and the number of repeaters ≳100. Presently, there is a consensus that most of the sources of FRBs might be neutron stars (NSs) with large magnetic fields. These objects might have different origin as suggested by studies of their host galaxies which represent a very diverse sample: from regions of very active star formation to old globular clusters. Thus, in the following decade we expect to have a very large sample of events directly related to extragalactic magnetars of different origin. This might open new possibilities to probe various aspects of NS physics. In the review we briefly discuss the main directions of such future studies and summarize our present knowledge about FRBs and their sources.
Citation: Particles
PubDate: 2023-03-21
DOI: 10.3390/particles6010025
Issue No: Vol. 6, No. 1 (2023)