Research

18 pages, 648 KiB

Open AccessFeature PaperArticle

Particle Multiplicity Fluctuations and Spatiotemporal Properties of Particle-Emitting Source of Strongly Interacting Matter for NICA and RHIC Energies

by Mariya Cheremnova, Alexey Chernyshov, Yevheniia Khyzhniak, Olga Kodolova, Valentin Kuzmin, Igor Lokhtin, Ludmila Malinina, Konstantin Mikhaylov and Grigory Nigmatkulov

Symmetry 2022, 14(7), 1316; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14071316 - 25 Jun 2022

Cited by 1 | Viewed by 1419

Abstract

The results of the model analysis of hadron femtoscopic correlations and factorial moments of particle multiplicity in heavy ion collisions for the energy range of the Beam Energy Scan (BES) program at RHIC and future NICA collider are presented. For this purpose, the [...] Read more.

The results of the model analysis of hadron femtoscopic correlations and factorial moments of particle multiplicity in heavy ion collisions for the energy range of the Beam Energy Scan (BES) program at RHIC and future NICA collider are presented. For this purpose, the simulation of Au+Au collisions at center-of-mass energies 7.7 and 11.5 GeV per nucleon pair using the UrQMD, vHLLE+UrQMD (with the crossover and first-order equation of states), and HYDJET++ event generators was performed. The sensitivity of pion and kaon correlation radii and the dependence of the factorial moments on heavy ion beam energy to quark–hadron phase transition details was studied. In addition, the possible influence of some relevant detector effects on the corresponding experimental observables is discussed. Full article

(This article belongs to the Special Issue Physics and Symmetry Section: Feature Papers 2021)

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23 pages, 396 KiB

Open AccessFeature PaperArticle

Topological BF Description of 2D Accelerated Chiral Edge Modes

by Erica Bertolini, Filippo Fecit and Nicola Maggiore

Symmetry 2022, 14(4), 675; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14040675 - 24 Mar 2022

Cited by 4 | Viewed by 1539

Abstract

In this paper, we consider the topological abelian BF theory with radial boundary on a generic 3D manifold, as we were motivated by the recently discovered accelerated edge modes on certain Hall systems. Our aim was to research if, where, and how the [...] Read more.

In this paper, we consider the topological abelian BF theory with radial boundary on a generic 3D manifold, as we were motivated by the recently discovered accelerated edge modes on certain Hall systems. Our aim was to research if, where, and how the boundary keeps the memory of the details of the background metrics. We discovered that some features were topologically protected and did not depend on the bulk metric. The outcome was that these edge excitations were

a c c e l e r a t e d

, as a direct consequence of the non-flat nature of the bulk spacetime. We found three possibilities for the motion of the edge quasiparticles: same directions, opposite directions, and a single-moving mode. However, requiring that the Hamiltonian of the 2D theory is bounded by below, the case of the edge modes moving in the same direction was ruled out. Systems involving parallel Hall currents (for instance, a fractional quantum Hall effect with

ν = 2 / 5

) cannot be described by a BF theory with the boundary, independently from the geometry of the bulk spacetime, because of positive energy considerations. Thus, we were left with physical situations characterized by edge excitations moving with opposite velocities (for example, the fractional quantum Hall effect with

ν = 1 - 1 / n

, with the n positive integer, and the helical Luttinger liquids phenomena) or a single-moving mode (quantum anomalous Hall). A strong restriction was obtained by requiring time reversal symmetry, which uniquely identifies modes with equal and opposite velocities, and we know that this is the case of topological insulators. The novelty, with respect to the flat bulk background, is that the modes have local velocities, which correspond to topological insulators with

a c c e l e r a t e d

edge modes. Full article

(This article belongs to the Special Issue Physics and Symmetry Section: Feature Papers 2021)

17 pages, 872 KiB

Open AccessArticle

Nonlinear Axion Electrodynamics: Axionically Induced Electric Flares in the Early Magnetized Universe

by Alexander B. Balakin, Vladimir V. Bochkarev and Albina F. Nizamieva

Symmetry 2021, 13(11), 2038; https://0-doi-org.brum.beds.ac.uk/10.3390/sym13112038 - 29 Oct 2021

Cited by 4 | Viewed by 1227

Abstract

We consider the nonlinearly extended Einstein–Maxwell-axion theory, which is based on the account for two symmetries: first, the discrete symmetry associated with the properties of the axion field, and second, the Jackson’s symmetry, prescribing to the electrodynamics to be invariant with respect to [...] Read more.

We consider the nonlinearly extended Einstein–Maxwell-axion theory, which is based on the account for two symmetries: first, the discrete symmetry associated with the properties of the axion field, and second, the Jackson’s symmetry, prescribing to the electrodynamics to be invariant with respect to the rotation in the plane coordinated by the electric and magnetic fields. We derive the master equations of the nonlinearly extended theory and apply them to the Bianchi-I model with magnetic field. The main result, describing the behavior of the nonlinearly coupled axion, electromagnetic, and gravitational fields is the anomalous growth of the axionically induced electric field in the early magnetized Universe. The character of behavior of this anomalous electric field can be indicated by the term flare. We expect, that these electric flares can produce the electron–positron pair creation, significant acceleration of the born charged particles, and the emission of the electromagnetic waves by these accelerated particles. Full article

(This article belongs to the Special Issue Physics and Symmetry Section: Feature Papers 2021)

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14 pages, 406 KiB

Open AccessFeature PaperArticle

Symmetries, Partners and Thresholds: The Case of the X_b

by Pablo G. Ortega, David R. Entem and Francisco Fernández

Symmetry 2021, 13(9), 1600; https://0-doi-org.brum.beds.ac.uk/10.3390/sym13091600 - 31 Aug 2021

Cited by 5 | Viewed by 1396

Abstract

The discovery of the

X (3872)

meant the revival of the heavy meson spectroscopy beyond naive

q \bar{q}

structures. Since the

S U (3)

scheme, which was very useful in the dawn of the quark models, does not [...] Read more.

The discovery of the

X (3872)

meant the revival of the heavy meson spectroscopy beyond naive

q \bar{q}

structures. Since the

S U (3)

scheme, which was very useful in the dawn of the quark models, does not work for these states, one has to use new symmetries, like Heavy Quark Spin Symmetry (HQSS) and Heavy Flavor Symmetry (HFS), to look for new states. However, at the energy regions where these new states appear, new factors are involved and it is not straightforward to relate the predictions of the symmetries with the data. In this work, we present a critical analysis of this problem and show, in a coupled-channels model, how the relative position of the bare

Q \bar{Q}

states with respect to meson-meson thresholds and the coupling with other channels modulate the strength of the interaction and, hence, modify the structure of the predicted states. We found a possible candidate to the

X (3872)

partner at 10,599 MeV

/ c^{2}

. Full article

(This article belongs to the Special Issue Physics and Symmetry Section: Feature Papers 2021)

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14 pages, 577 KiB

Open AccessArticle

The Energy of the Ground State of the Two-Dimensional Hamiltonian of a Parabolic Quantum Well in the Presence of an Attractive Gaussian Impurity

by Silvestro Fassari, Manuel Gadella, Luis Miguel Nieto and Fabio Rinaldi

Symmetry 2021, 13(9), 1561; https://0-doi-org.brum.beds.ac.uk/10.3390/sym13091561 - 25 Aug 2021

Cited by 2 | Viewed by 1585

Abstract

In this article, we provide an expansion (up to the fourth order of the coupling constant) of the energy of the ground state of the Hamiltonian of a quantum mechanical particle moving inside a parabolic well in the x-direction and constrained by [...] Read more.

In this article, we provide an expansion (up to the fourth order of the coupling constant) of the energy of the ground state of the Hamiltonian of a quantum mechanical particle moving inside a parabolic well in the x-direction and constrained by the presence of a two-dimensional impurity, modelled by an attractive two-dimensional isotropic Gaussian potential. By investigating the associated Birman–Schwinger operator and exploiting the fact that such an integral operator is Hilbert–Schmidt, we use the modified Fredholm determinant in order to compute the energy of the ground state created by the impurity. Full article

(This article belongs to the Special Issue Physics and Symmetry Section: Feature Papers 2021)

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12 pages, 300 KiB

Open AccessArticle

Antimatter Free-Fall Experiments and Charge Asymmetry

by Ulrich David Jentschura

Symmetry 2021, 13(7), 1192; https://0-doi-org.brum.beds.ac.uk/10.3390/sym13071192 - 01 Jul 2021

Viewed by 1956

Abstract

We propose a method by which one could use modified antimatter gravity experiments in order to perform a high-precision test of antimatter charge neutrality. The proposal is based on the application of a strong, external, vertically oriented electric field during an antimatter free-fall [...] Read more.

We propose a method by which one could use modified antimatter gravity experiments in order to perform a high-precision test of antimatter charge neutrality. The proposal is based on the application of a strong, external, vertically oriented electric field during an antimatter free-fall gravity experiment in the gravitational field of the Earth. The proposed experimental setup has the potential to drastically improve the limits on the charge-asymmetry parameter

{\bar{ϵ}}_{q}

of antimatter. On the theoretical side, we analyze possibilities to describe a putative charge-asymmetry of matter and antimatter, proportional to the parameters

ϵ_{q}

and

{\bar{ϵ}}_{q}

, by Lagrangian methods. We found that such an asymmetry could be described by four-dimensional Lorentz-invariant operators that break CPT without destroying the locality of the field theory. The mechanism involves an interaction Lagrangian with field operators decomposed into particle or antiparticle field contributions. Our Lagrangian is otherwise Lorentz, as well as PT invariant. Constraints to be derived on the parameter

{\bar{ϵ}}_{q}

do not depend on the assumed theoretical model. Full article

(This article belongs to the Special Issue Physics and Symmetry Section: Feature Papers 2021)

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6 pages, 1201 KiB

Open AccessArticle

What Density of Magnetosheath Sodium Ions Can Provide the Observed Decrease in the Magnetic Field of the “Double Magnetopause” during the First MESSENGER Flyby?

by Elena Belenkaya and Ivan Pensionerov

Symmetry 2021, 13(7), 1168; https://0-doi-org.brum.beds.ac.uk/10.3390/sym13071168 - 29 Jun 2021

Cited by 3 | Viewed by 1240

Abstract

On 14 January 2008, the MESSENGER spacecraft, during its first flyby around Mercury, recorded the magnetic field structure, which was later called the “double magnetopause”. The role of sodium ions penetrating into the Hermean magnetosphere from the magnetosheath in generation of this structure [...] Read more.

On 14 January 2008, the MESSENGER spacecraft, during its first flyby around Mercury, recorded the magnetic field structure, which was later called the “double magnetopause”. The role of sodium ions penetrating into the Hermean magnetosphere from the magnetosheath in generation of this structure has been discussed since then. The violation of the symmetry of the plasma parameters at the magnetopause is the cause of the magnetizing current generation. Here, we consider whether the change in the density of sodium ions on both sides of the Hermean magnetopause could be the cause of a wide diamagnetic current in the magnetosphere at its dawn-side boundary observed during the first MESSENGER flyby. In the present paper, we propose an analytical approach that made it possible to determine the magnetosheath Na⁺ density excess providing the best agreement between the calculation results and the observed magnetic field in the double magnetopause. Full article

(This article belongs to the Special Issue Physics and Symmetry Section: Feature Papers 2021)

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19 pages, 2096 KiB

Open AccessArticle

Late Time Attractors of Some Varying Chaplygin Gas Cosmological Models

by Martiros Khurshudyan and Ratbay Myrzakulov

Symmetry 2021, 13(5), 769; https://0-doi-org.brum.beds.ac.uk/10.3390/sym13050769 - 28 Apr 2021

Cited by 1 | Viewed by 1689

Abstract

The goal of this paper is to study new cosmological models where the dark energy is a varying Chaplygin gas. This specific dark energy model with non-linear EoS had been often discussed in modern cosmology. Contrary to previous studies, we consider new forms [...] Read more.

The goal of this paper is to study new cosmological models where the dark energy is a varying Chaplygin gas. This specific dark energy model with non-linear EoS had been often discussed in modern cosmology. Contrary to previous studies, we consider new forms of non-linear non-gravitational interaction between dark matter and assumed dark energy models. We applied the phase space analysis allowing understanding the late time behavior of the models. It allows demonstrating that considered non-gravitational interactions can solve the cosmological coincidence problem. On the other hand, we applied Bayesian Machine Learning technique to learn the constraints on the free parameters. In this way, we gained a better understanding of the models providing a hint which of them can be ruled out. Moreover, the learning based on the simulated expansion rate data shows that the models cannot solve the

H_{0}

tension problem. Full article

(This article belongs to the Special Issue Physics and Symmetry Section: Feature Papers 2021)

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12 pages, 295 KiB

Open AccessArticle

Analogies between Logistic Equation and Relativistic Cosmology

by Steve Dussault, Valerio Faraoni and Andrea Giusti

Symmetry 2021, 13(4), 704; https://0-doi-org.brum.beds.ac.uk/10.3390/sym13040704 - 17 Apr 2021

Cited by 2 | Viewed by 1813

Abstract

We develop several formal analogies between the logistic equation and the spatially homogeneous and isotropic relativistic cosmology described by the Einstein–Friedmann equations. These analogies produce an effective Lagrangian and Hamiltonian and new symmetries for the logistic equation. Full article

(This article belongs to the Special Issue Physics and Symmetry Section: Feature Papers 2021)

12 pages, 768 KiB

Open AccessArticle

Ab Initio Spectroscopic Investigation of Pharmacologically Relevant Chiral Molecules: The Cases of Avibactam, Cephems, and Idelalisib as Benchmarks for Antibiotics and Anticancer Drugs

by Elena Molteni, Giovanni Onida, Matteo Ceccarelli and Giancarlo Cappellini

Symmetry 2021, 13(4), 601; https://0-doi-org.brum.beds.ac.uk/10.3390/sym13040601 - 03 Apr 2021

Cited by 2 | Viewed by 1973

Abstract

The ability to accurately measure or predict several physicochemical properties of molecules which play a role as active substances in drugs can be of strategic importance for pharmacological applications, in addition to its possible interest in fundamental research. Chirality is a relevant feature [...] Read more.

The ability to accurately measure or predict several physicochemical properties of molecules which play a role as active substances in drugs can be of strategic importance for pharmacological applications, in addition to its possible interest in fundamental research. Chirality is a relevant feature in the characterization of drug molecules: enantiomers can show different pharmacological activity and adverse effects. The ability to separate stereoisomers and to assign their absolute configuration can thus be crucial. Circular dichroism (CD) spectra are a useful tool to distinguish between enantiomers. In this work we apply an in-house developed code, based on an efficient DFT approach for circular dichroism, to fully characterize the molecular optical properties in the case of few selected fundamental molecules for current medical and pharmaceutical research, namely avibactam, as representative of non

β

-lactam inhibitors, two cephems (cefepime and cefoxitin), as examples of

β

-lactam antibiotics, and idelalisib, as a recent relevant anticancer active substance to treat major leukemias. For the above molecules, in addition to their optical absorption spectra, we calculate their CD spectra within state-of-the-art computational techniques. We then investigate both the conformational and chemical sensitivity of absorption and CD spectra for the chosen molecules. The outcomes of the present research could be of fundamental importance to gain additional information on molecules involved in therapeutic protocols for severe diseases or in drug design. Full article

(This article belongs to the Special Issue Physics and Symmetry Section: Feature Papers 2021)

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128 pages, 6748 KiB

Open AccessArticle

The Cosmological OTOC: A New Proposal for Quantifying Auto-Correlated Random Non-Chaotic Primordial Fluctuations

by Sayantan Choudhury

Symmetry 2021, 13(4), 599; https://0-doi-org.brum.beds.ac.uk/10.3390/sym13040599 - 03 Apr 2021

Cited by 17 | Viewed by 1921

Abstract

The underlying physical concept of computing out-of-time-ordered correlation (OTOC) is a significant new tool within the framework of quantum field theory, which now-a-days is treated as a measure of random fluctuations. In this paper, by following the canonical quantization technique, we demonstrate a [...] Read more.

The underlying physical concept of computing out-of-time-ordered correlation (OTOC) is a significant new tool within the framework of quantum field theory, which now-a-days is treated as a measure of random fluctuations. In this paper, by following the canonical quantization technique, we demonstrate a computational method to quantify the two different types of cosmological auto-correlated OTO functions during the epoch when the non-equilibrium features dominates in primordial cosmology. In this formulation, two distinct dynamical time scales are involved to define the quantum mechanical operators arising from the cosmological perturbation scenario. We have provided detailed explanation regarding the necessity of this new formalism to quantify any random events generated from quantum fluctuations in primordial cosmology. We have performed an elaborative computation for the two types of two-point and four-point auto-correlated OTO functions in terms of the cosmological perturbation field variables and its canonically conjugate momenta to quantify random auto-correlations in the non-equilibrium regime. For both of the cases, we found significantly distinguishable non-chaotic, but random, behaviour in the OTO auto-correlations, which was not pointed out before in this type of study. Finally, we have also demonstrated the classical limiting behaviour of the mentioned two types of auto-correlated OTOC functions from the thermally weighted phase-space averaged Poisson brackets, which we found to exactly match the large time limiting behaviour of the auto-correlations in the super-horizon regime of the cosmological scalar mode fluctuation. Full article

(This article belongs to the Special Issue Physics and Symmetry Section: Feature Papers 2021)

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