Advances in High Energy Physics
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Published By Hindawi Limited

1687-7365, 1687-7357

2021 ◽  
Vol 2021 ◽  
pp. 1-5
Author(s):  
Kai Lin

This work discusses the black hole thermodynamics in a weak dynamical Anti-de Sitter spacetime, which should be described by the nonequilibrium thermodynamics, because the metric depends on the time coordinate. Taking the Vaidya-Anti-de Sitter black hole spacetime as an example, the local entropy balance equations and principle of minimum entropy generation are derived, and finally, some irreversible effects in nonequilibrium thermodynamics are studied by using the Onsager reciprocal relation.


2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zhi-Gang Wang

In this article, we take into account our previous calculations based on the QCD sum rules, and tentatively assign the X 4630 as the D s ∗ D ¯ s 1 − D s 1 D ¯ s ∗ tetraquark molecular state or c s P c ¯ s ¯ A + c s A c ¯ s ¯ P tetraquark state with the J P C = 1 − + , and assign the X 3915 and X 4500 as the 1S and 2S c s A c ¯ s ¯ A tetraquark states, respectively, with the J P C = 0 + + . Then, we extend our previous works to investigate the LHCb’s new tetraquark candidate X 4685 as the first radial excited state of the X 4140 with the QCD sum rules and obtain the mass M X = 4.70 ± 0.12   GeV , which is in very good agreement with the experimental value 4684 ± 7 − 16 + 13   MeV . Furthermore, we investigate the two-meson scattering state contributions in details and observe that the two-meson scattering states alone cannot saturate the QCD sum rules, the contributions of the tetraquark states play an unsubstitutable role, and we can saturate the QCD sum rules with or without the two-meson scattering states.


2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Mahmoud Hanafy ◽  
Omnia S. A. Qandil ◽  
Asmaa G. Shalaby

The strangeness enhancement signature of QGP formation at LHC energies is carefully tackled in the present study. Based on HRG, the particle ratios of mainly strange and multistrange particles are studied at energies from lower s ~ 0.001 up to 13 TeV. The strangeness enhancement clearly appeared at more high energies, and the ratios are confronted to the available experimental data. The particle ratios are also studied using the Cosmic Ray Monte Carlo (CRMC) interface model with its two different event generators, namely, EPOS 1.99 and EPOSlhc, which show a good agreement with the model calculations at the whole range of the energy. We utilize them to produce some particles ratios. EPOS 1.99 is used to estimate particle ratios at lower energies from AGS up to the Relativistic Heavy Ion Collider (RHIC) while EPOSlhc is used at LHC energies. The production of kaons and lambda particles is studied in terms of the mean multiplicity in p-p collisions at energies ranging from 4 to 26 GeV. We find that both HRG model and the used event generators, EPOS 1.99 and EPOSlhc, can describe the particle ratios very well. Additionally, the freeze-out parameters are estimated for different collision systems, such as p-p and Pb-Pb, at LHC energies using both models.


2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Márcio M. Cunha ◽  
Edilberto O. Silva

In this manuscript, we study the relativistic quantum mechanics of an electron in external fields in the spinning cosmic string spacetime. We obtain the Dirac equation and write the first- and second-order equations from it, and then, we solve these equations for bound states. We show that there are bound state solutions for the first-order equation Dirac. For the second-order equation, we obtain the corresponding wave functions, which depend on the Kummer functions. Then, we determine the energies of the particle. We examine the behavior of the energies as a function of the physical parameters of the model, such as rotation, curvature, magnetic field, Aharonov-Bohm flux, and quantum numbers. We find that, depending on the values of these parameters, there are energy nonpermissible levels.


2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
M. I. Wanas ◽  
Mona M. Kamal

Using a geometry wider than Riemannian one, the parameterized absolute parallelism (PAP) geometry, we derived a new curve containing two parameters. In the context of the geometrization philosophy, this new curve can be used as a trajectory of charged spinning test particle in any unified field theory constructed in the PAP space. We show that imposing certain conditions on the two parameters, the new curve can be reduced to a geodesic curve giving the motion of a scalar test particle or/and a modified geodesic giving the motion of neutral spinning test particle in a gravitational field. The new method used for derivation, the Bazanski method, shows a new feature in the new curve equation. This feature is that the equation contains the electromagnetic potential term together with the Lorentz term. We show the importance of this feature in physical applications.


2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Bouzid Boussaha ◽  
Tariq Bitam

This paper is aimed at studying the feasibility of building an Earth-skimming cosmic tau neutrinos detector, with the aim of eventually identifying the ideal dimensions of a natural site mountain-valley for the detection of very high energy neutrinos tau range from 1 0 16 eV to 1 0 20 eV , as well as possibly locate one such site in Algeria. First, a Monte Carlo simulation of the neutrino-[mountain] matter interaction as well as the resulting decay of the tau lepton is conducted to determine the optimal dimensions of the mountain as well as the location of the tau decay in the valley. Second, a CORSIKA (COsmic Ray Simulation for KAscade) simulation with the CONEX option is conducted to track the evolution of the almost horizontal air shower initiated by the tau lepton. Many particles are produced, which are part of the shower components: electrons, muons, gammas, pions, etc. The study of the spatial distribution of these particles enables the discovery of the optimal width of the valley, and consequently, the distance at which to lay the detection network.


2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
M. Farasat Shamir ◽  
Ammara Usman ◽  
Tayyaba Naz

The main aim of our study is to explore some relativistic configurations of compact object solution in the background of f R gravity, by adopting the Krori-Barua spacetime. In this regard, we establish the field equations for spherically symmetric spacetime along with charged anisotropic matter source by assuming the specific form of the metric potentials, i.e., ν r = B r 2 + C and λ r = A r 2 . Further, to calculate the constant values, we consider the Bardeen model as an exterior spacetime at the surface boundary. To ensure the viability of the f R gravity model, the physical characteristics including energy density, pressure components, energy bonds, equilibrium condition, Herrera cracking concept, mass-radius relation, and adiabatic index are analyzed in detail. It is observed that all the outcomes by graphical exploration and tabular figures show that the Bardeen black hole model describes the physically realistic stellar structures.


2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Ho-Meoyng Choi

We investigate the exclusive semileptonic and rare D ⟶ π K decays within the standard model together with the light-front quark model (LFQM) constrained by the variational principle for the QCD-motivated effective Hamiltonian. The form factors are obtained in the q + = 0 frame and then analytically continue to the physical timelike region. Together with our recent analysis of the current-component independent form factors f ± q 2 for the semileptonic decays, we present the current-component independent tensor form factor f T q 2 for the rare decays to make the complete set of hadronic matrix elements regulating the semileptonic and rare D ⟶ π K decays in our LFQM. The tensor form factor f T q 2 are obtained from two independent sets J T + ⊥ , J T + − of the tensor current J T u v . As in our recent analysis of f − q 2 , we show that f T q 2 obtained from the two different sets of the current components gives the identical result in the valence region of the q + = 0 frame without involving the explicit zero modes and the instantaneous contributions. The implications of the zero modes and the instantaneous contributions are also discussed in comparison between the manifestly covariant model and the standard LFQM. In our numerical calculations, we obtain the q 2 -dependent form factors ( f ± , f T ) for D ⟶ π K and branching ratios for the semileptonic D ⟶ π K ℓ v ℓ ℓ = e , μ decays. Our results show in good agreement with the available experimental data as well as other theoretical model predictions.


2021 ◽  
Vol 2021 ◽  
pp. 1-24
Author(s):  
A. Tripathi ◽  
B. Chauhan ◽  
A. K. Rao ◽  
R. P. Malik

We carry out the Becchi-Rouet-Stora-Tyutin (BRST) quantization of the one 0 + 1 -dimensional (1D) model of a free massive spinning relativistic particle (i.e., a supersymmetric system) by exploiting its classical infinitesimal and continuous reparameterization symmetry transformations. We use the modified Bonora-Tonin (BT) supervariable approach (MBTSA) to BRST formalism to obtain the nilpotent (anti-)BRST symmetry transformations of the target space variables and the (anti-)BRST invariant Curci-Ferrari- (CF-) type restriction for the 1D model of our supersymmetric (SUSY) system. The nilpotent (anti-)BRST symmetry transformations for other variables of our model are derived by using the (anti-)chiral supervariable approach (ACSA) to BRST formalism. Within the framework of the latter, we have shown the existence of the CF-type restriction by proving the (i) symmetry invariance of the coupled Lagrangians and (ii) the absolute anticommutativity property of the conserved (anti-)BRST charges. The application of the MBTSA to a physical SUSY system (i.e., a 1D model of a massive spinning particle) is a novel result in our present endeavor. In the application of ACSA, we have considered only the (anti-)chiral super expansions of the supervariables. Hence, the observation of the absolute anticommutativity of the (anti-)BRST charges is a novel result. The CF-type restriction is universal in nature as it turns out to be the same for the SUSY and non-SUSY reparameterization (i.e., 1D diffeomorphism) invariant models of the (non-)relativistic particles.


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