Ion acoustic solitary waves in magnetized anisotropic nonextensive plasmas

The nonlinear propagation of ion-acoustic (IA) electrostatic solitary waves (SWs) is studied in a magnetized electron–ion (e–i) plasma in the presence of pressure anisotropy with electrons following Tsallis distribution. The Korteweg–de Vries (KdV) type equation is derived by employing the reductive perturbation method (RPM) and its solitary wave (SW) solution is determined and analyzed. The effect of nonextensive parameter q, parallel component of anisotropic ion pressure p 1, perpendicular component of anisotropic ion pressure p 2, obliqueness angle θ, and magnetic field strength Ω on the characteristics of SW structures is investigated. The present investigation could be useful in space and astrophysical plasma systems.

Non-extensive transverse momentum distribution for identified particles at SNN = 7.7, 11.5, 19.6, 27, 39GeV

The transverse momentum distribution of charged particles formed in Au–Au collisions at Beam Energy Scan (BES) ([Formula: see text][Formula: see text]GeV) is investigated. In addition, [Formula: see text] spectra of [Formula: see text] particle at [Formula: see text][Formula: see text]GeV were examined. Tsallis distribution is used to extract the temperature, volume and the entropic index from the experimental results at mid-rapidity and zero chemical potential. We measure some particle ratios like [Formula: see text] and [Formula: see text] which are puzzling horn in the experiment and in the thermal model. We conclude that the horn vanished when we used Tsallis distribution, but this does not confirm a solution to the puzzle, which is primarily visible in the experimental results.

Theoretical analysis of pT spectra of light-flavor hadrons in p + p collisions at s = 7 TeV under differential and single freeze-out scenarios

We present the published data of ALICE at mid-rapidity region ([Formula: see text]) to study the [Formula: see text] spectra of light-flavor hadrons in different charged-particle multiplicities ([Formula: see text]) for [Formula: see text] collisions at [Formula: see text] TeV. We parametrize the [Formula: see text] spectra of different hadrons such as pion ([Formula: see text]), kaon ([Formula: see text]), [Formula: see text], [Formula: see text] ([Formula: see text]), [Formula: see text], proton ([Formula: see text]), lambda ([Formula: see text]), cascade ([Formula: see text]) and omega ([Formula: see text]) using Tsallis distribution. We perform this analysis by considering both differential and single freeze-out scenarios. In the differential freeze-out scenario, both the Tsallis parameters [Formula: see text] and [Formula: see text] increase with charged multiplicities for most of the particles. This implies that the multipartonic interactions increase the multiplicities in [Formula: see text] collisions and it brings the system towards thermal equilibrium. Here we observe that both [Formula: see text] and [Formula: see text] have different trends with different masses of particles. The parameters [Formula: see text] and [Formula: see text] are higher for massive particles (except for multistrange baryons) in comparison to lighter ones, which supports the differential freeze-out scenario and suggests that massive particles freeze-out earlier from the system. In the case of single freeze-out scenario, the value of parameter [Formula: see text] has a little variation with multiplicity and the parameter [Formula: see text] increases with multiplicity. This implies that the degree of thermalization remains similar for the events of different multiplicity classes.

Phenomenological Tsallis distribution from thermal field theory

Classical and quantum Tsallis distributions have been widely used in many branches of natural and social sciences. But, the quantum field theory of the Tsallis distributions is relatively a less explored arena. In this paper, we derive the expression for the thermal two-point functions in the Tsallis statistics with the help of the corresponding statistical mechanical formulations. We show that the quantum Tsallis distributions used in the literature appear in the thermal part of the propagator much in the same way the Boltzmann–Gibbs distributions appear in the conventional thermal field theory. As an application of our findings, we calculate the thermal mass in the [Formula: see text] scalar field theory within the realm of the Tsallis statistics.

Beyond the relaxation time approximation

The relaxation time approximation (RTA) is a well known method of describing the time evolution of a statistical ensemble by linking distributions of the variables of interest at different stages of their temporal evolution. We show that if all the distributions occurring in the RTA have the same functional form of a quasi-power Tsallis distribution the time evolution of which depends on the time evolution of its control parameter, nonextensivity q(t), then it is more convenient to consider only the time evolution of this control parameter.

Centrality, transverse momentum and collision energy dependence of the Tsallis parameters in relativistic heavy-ion collisions

The thermodynamic properties of matter created in high-energy heavy-ion collisions have been studied in the framework of the non-extensive Tsallis statistics. The transverse momentum ($$p_\mathrm{T}$$ p T ) spectra of identified charged particles (pions, kaons, protons) and all charged particles from the available experimental data of Au-Au collisions at the Relativistic Heavy Ion Collider (RHIC) energies and Pb-Pb collisions at the Large Hadron Collider (LHC) energies are fitted by the Tsallis distribution. The fit parameters, q and T, measure the degree of deviation from an equilibrium state and the effective temperature of the thermalized system, respectively. The $$p_\mathrm{T}$$ p T spectra are well described by the Tsallis distribution function from peripheral to central collisions for the wide range of collision energies, from $$\sqrt{s_\mathrm{NN}}$$ s NN = 7.7 GeV to 5.02 TeV. The extracted Tsallis parameters are found to be dependent on the particle species, collision energy, centrality, and fitting ranges in $$p_\mathrm{T}$$ p T . For central collisions, both q and T depend strongly on the fit ranges in $$p_\mathrm{T}$$ p T . For most of the collision energies, q remains almost constant as a function of centrality, whereas T increases from peripheral to central collisions. For a given centrality, q systematically increases as a function of collision energy, whereas T has a decreasing trend. A profile plot of q and T with respect to collision energy and centrality shows an anti-correlation between the two parameters.

Study of Production of (Anti-)deuteron Observed in Au+Au Collisions at s NN = 14.5 , 62.4, and 200 GeV

Transverse momentum distributions of deuterons and antideuterons in Au + Au collisions at s NN = 14.5 , 62.4, and 200 GeV with different centrality are studied in the framework of the multisource thermal model. Transverse momentum spectra are conformably and approximately described by the Tsallis distribution. The dependence of parameters (average transverse momenta, effective temperature, and entropy index) on event centrality is obtained. It is found that the parameters T increase and q decrease with increase of the average number of particles involved in collisions, which reveals the transverse excitation degree increases with collision centrality.

Medium effects of charged particles in Xe+Xe collisions at s NN = 5.44 TeV using modified Tsallis distribution

We present a systematic study of transverse momentum [Formula: see text] spectra of charged particles in [Formula: see text] and Xe[Formula: see text]Xe collisions at [Formula: see text] TeV. The published data of invariant yields of charged particles as a function of [Formula: see text] is taken from ALICE at LHC in the mid-pseudorapidity region [Formula: see text]. The modified form of Tsallis distribution is used here to analyze the [Formula: see text] spectra of charged particles. The power law of Tsallis/Hagedorn form gives very good description of the charged particle spectra in [Formula: see text] collisions within a [Formula: see text] range of 0.15 GeV/[Formula: see text] to 50 GeV/[Formula: see text]. When we go from [Formula: see text] collisions to heavy-ion (Xe[Formula: see text]Xe) collisions, the original form of Tsallis/Hagedorn distribution is not able to describe the [Formula: see text] spectra of charged particles properly. This may be occurred due to the medium effects or the final state effects. Here we discuss two types of medium effects of charged particles in Xe[Formula: see text]Xe collisions, one is the transverse flow in the low to intermediate [Formula: see text] region ([Formula: see text] GeV/[Formula: see text]) and the other is the energy loss in the high [Formula: see text] region ([Formula: see text] GeV/[Formula: see text]), using the modified Tsallis distribution.

Head-on collision of two ion-acoustic solitons in pair-ion plasmas with nonthermal electrons featuring Tsallis distribution

The head-on collision between two ion-acoustic solitons (IASs) is studied in pair ions plasmas with hybrid Cairns–Tsallis-distributed electrons. The chosen model is inspired from the experimental studies of Ichiki et al. [Phys. Plasmas 8, 4275 (2001)]. The extended Poincaré–Lighthill–Kuo (PLK) method is employed to obtain the phase shift due to the IASs collision. Both analytical and numerical results reveal that the magnitude of the phase shift is significantly affected by the nonthermal and nonextensive parameters (α and q), the number density ratios (μ and υ) as well as the mass ratio σ. For a given mass ratio σ ≃ 0.27 $\sigma \simeq 0.27$ (Ar+, SF 6 − ${\text{SF}}_{6}^{-}$ ), the magnitude of the phase shift Δ Q ( 0 ) ${\Delta}{Q}^{\left(0\right)}$ decreases slightly (increases) with the increase of q (α). The effect of α on Δ Q ( 0 ) ${\Delta}{Q}^{\left(0\right)}$ is more noticeable in the superextensive distribution case (q < 1). As σ increases [ σ ≃ 0.89 $\sigma \simeq 0.89$ (Xe+, SF 6 − ${\text{SF}}_{6}^{-}$ )], the phase shift becomes wider. In other terms, the phase shift was found to be larger under the effect of higher densities of the negative ions. Our findings should be useful for understanding the dynamics of IA solitons’ head-on collision in space environments [namely, D-regions ( H + ${\text{H}}^{+}$ , O 2 − ${\text{O}}_{2}^{-}$ ) and F-regions (H+, H−) of the Earth’s ionosphere] and in laboratory double pair plasmas [namely, fullerene (C+, C−) and laboratory experiment (Ar+, F−)].