Modern Physics Letters A

The experimental invariant transverse momentum $(p_t)$ spectra of the charged pions and kaons, protons and antiprotons, produced at midrapidity in central (0–10%) Au$+$Au collisions at ${(s_{nn})}^{1/2}=62.4\mathrm{\text{GeV}}$, central (0–10%) Cu$+$Cu collisions at ${(s_{nn})}^{1/2}=200\mathrm{\text{GeV}}$, central (0–10%) Au$+$Au collisions at ${(s_{nn})}^{1/2}=200\mathrm{\text{GeV}}$, and central (0–5%) Pb$+$Pb collisions at ${(s_{nn})}^{1/2}=2.76\mathrm{\text{TeV}}$, measured by BRAHMS, STAR and ALICE collaborations, were analyzed using three different transverse expansion (blast-wave) models: Siemens–Rasmussen blast-wave model, Simple transverse flow model, and Simplified (hydro-inspired) blast-wave model of Schnedermann et al. Combined (simultaneous) minimum ${\chi }^2$ fits of the experimental invariant $p_t$ spectra of the charged pions and kaons, protons and antiprotons with the above three model functions were conducted, using the identical selected optimal fitting ranges in $p_t$ in each studied collision system, and the values of the average transverse expansion velocity $(〈{\beta }_t〉)$ and global kinetic freeze-out temperature $(T_{fo})$ and their dependencies on the collision system $(〈N_{\mathrm{\text{part}}}〉)$ and ${(s_{nn})}^{1/2}$ were extracted. The combined (simultaneous) fits using Hagedorn formula with the (embedded) simple transverse flow describe well the experimental invariant $p_t$ spectra of the charged pions, kaons, protons and antiprotons in the whole measured range in region $p_t\ge 0.5\mathrm{\text{GeV}}/c$ in the analyzed central heavy ion collisions at RHIC and LHC, reproducing qualitatively well all the established dependencies of the parameters $〈{\beta }_t〉$ and $T_{fo}$ on the collision system $(〈N_{\mathrm{\text{part}}}〉)$ and ${(s_{nn})}^{1/2}$. The obtained results were compared with those of the previous analyses of high energy heavy ion collisions.

In this paper, we study four-quark states as di-hadronic molecular states. For this purpose, we apply the Nikiforov–Uvarov method to solve the Schrödinger equation in the presence of the Woods–Saxon plus Coulomb-type potential and we obtain the binding energies and masses of heavy di-mesons. We calculate the root mean square (r.m.s) radius and the wave function for some observed tetraquarks.

In this paper, we compare different measurement strategies for estimating coupling strength of a Hamiltonian. In particular, we estimate the coupling strength coefficient when the Hamiltonian couples the pointer (measuring device) momentum to an observable of the system. We compare the performance of the estimations via four different measurement strategies: measuring the position or the momentum of the pointer with or without postselection of the system state. Without postselection, it turns out that all the information of the coupling strength can be extracted by measuring the position of the pointer. As a contrast, no information of the coupling strength can be extracted if the momentum is measured without postselection. Hence, measuring the position is a better choice if postselection is not allowed. However, when postselection is employed, we find that no matter which observable is measured, one can always achieve a great amplification of the measurement outcome, which can be larger than the initial standard deviation of the pointer observable under certain circumstances, at an acceptable cost of losing a little accuracy for the estimation of the coupling strength. With postselection, the better choice of the observable to be measured depends on the characteristic of the measurement devices.

The relationship between the elastic scattering phase shifts of the $\mathrm{\Omega }\mathrm{\Omega }$ system and the two-particle energy spectrum in elongated boxes is established in center-of-mass frame under periodic boundary conditions. The formulas are also extended to cubic boxes to confirm the results in elongated boxes. Our analytical results will be helpful to the study of $\mathrm{\Omega }\mathrm{\Omega }$ interaction on lattice by using Lüscher’s finite volume method.

In this study, we have investigated generalized anisotropic universe models for magnetized strange quark matter (MSQM) distribution in the framework of $f(R)$ gravitation theory. For this aim, we have used linearly varying deceleration parameter suggested by Akarsu and Dereli (2012) and equation of state for strange quark matter. For LRS Bianchi I universe model, the magnetic field was obtained as zero. But it was found to be different from zero for other universe models. Also, the geometric and physical aspects of the model are discussed in the conclusion.

We study the cosmological consequences of interacting Tsallis holographic dark energy model in the framework of the fractal universe in which the Hubble radius is considered as the IR cutoff. We derive the equation of state (EoS) parameter, deceleration parameter and the evolution equation for the Tsallis holographic dark energy density parameter. Our study shows that this model can describe the current accelerating universe in both non-interacting and interacting scenarios, and also a transition occurs from the deceleration phase to the accelerated phase at the late-time. Finally, we check the compatibility of free parameters of the model with the latest observational results by using the Pantheon supernovae data, eBOSS, 6df, BOSS DR12, CMB Planck 2015, Gamma-Ray Burst.

In this paper, we study perfect, anisotropic and anisotropic dissipative cylindrical quark star for the tilted observer. To this end, the field equations and dynamical equations are formulated and assume MIT bag model to find a numerical solution of the field equations. The behavior of resulting model is investigated by plotting density, pressure, anisotropy and energy conditions. We check viability of the solutions through physical features related to stellar matter configuration. Finally, we discuss stability for all the cases of fluid distribution.

This paper is keen to study the generalized DBI-inspired non-minimal kinetic coupling inflationary model with non-interacting imperfect fluid in the framework of FRW universe. This is a newly proposed model with an interesting feature of having a correction term $k^4$ in the perturbed equation of motion due to the nonlinearity of the kinetic term. The power spectrum remains scale invariant both in large-$k$ and small-$k$ limits. In order to discuss the inflationary dynamics, the non-interacting inflaton and imperfect fluid including bulk viscosity are considered to be the cosmic matter contents. We consider large field potential and derive the exact solution of inflaton and perturbed parameters. Further, we investigate the nature of the perturbed parameters in detail, specifically on the potential-driven case, and compare the consequences to the current PLANCK/BICEP observational data. We also analyze the corresponding tensor spectrum, which will be tested by the future observations on primordial gravitational waves.

We analyze the transverse Kähler–Ricci flow equation on Sasaki-Einstein space $Y^{p,q}$. Explicit solutions are produced representing new five-dimensional Sasaki structures. Solutions which do not modify the transverse metric preserve the Sasaki–Einstein feature of the contact structure. If the transverse metric is altered, the deformed metrics remain Sasaki, but not Einstein.

In this paper, we study the thermodynamic of the charged AdS black holes in Rastall gravity. Firstly, the thermodynamic quantities of the charged AdS black holes in Rastall gravity are reviewed and the state equation of this black hole is obtained. Then, we investigate the $P-V$ critical and the Joule–Thomson expansion of the charged AdS black holes in Rastall gravity in which the critical temperature and the critical exponents are obtained. In addition, we get the inversion temperature and plot the isenthalpic and inversion curves in the $T-P$ plane, and also determine the cooling-heating regions of this black hole through the Joule–Thomson expansion. Finally, we investigate the ratio between the minimum inversion and critical temperatures, and find that the Rastall constant $b$ does not affect of this ratio.