International Journal of Modern Physics A

Based upon the color-dipole picture, we provide closed analytic expressions for the longitudinal and the transverse photoabsorption cross-sections at low values of the Bjorken variable of $x\lesssim 0.1$. We compare with the experimental data for the longitudinal-to-transverse ratio of the (virtual) photoabsorption cross-section and with our previous fit to the experimental data for the total photoabsorption cross-section. Scaling in terms of the low-$x$ scaling variable $\eta (W^2,Q^2)$ is analyzed in terms of the reduced cross-section of deep inelastic scattering.

Complete expressions of the $\bar{s}bg$ and $\bar{s}b\gamma$ vertices are derived in the framework of minimal supersymmetric extension of the standard model. With some assumptions on parameters of the model, a numerical analysis of the supersymmetric contributions to the branching ratio and CP-asymmetry of $\bar{B}\to X_{{}_s}\gamma$ is presented.

In this paper, using a deformed algebra $[X,P]=i\hslash /(1-{\alpha }^2{P}^2)$ which is originated from various theories of gravity, we study thermodynamical properties of the classical and extreme relativistic gases in canonical ensembles. In this regards, we exactly calculate the modified partition function, Helmholtz free energy, internal energy, entropy, heat capacity and the thermal pressure which conclude to the familiar form of the equation of state for the ideal gas. The advantage of applying this algebra is not only considering all natural cutoffs but also its structure is similar to the other effective quantum gravity models such as polymer, Snyder and noncommutative space–time frameworks. Moreover, after obtaining some thermodynamical quantities including internal energy and entropy, we conclude at high temperature limits due to the decreasing of the number of microstates, these quantities reach to maximal bounds which do not exist in standard cases and it concludes that at the presence of gravity for both micro-canonic and canonic ensembles, the internal energy and the entropy tend to these upper bounds.

Inspired by the recent measurements on two-body nonleptonic $J/\psi$ weak decay at BESIII, the charm-changing $J/\psi \to D_{s,d}V$ weak decays are studied with perturbative QCD approach, where $V$ denotes $\rho$ and $K^{\ast }$ vector mesons. It is found that branching ratio for $J/\psi \to D_s\rho$ decay can reach up to ${𝒪}(10^{-9})$, which is within the potential measurement capability of the future high-luminosity experiments.

This paper examines the interaction of an intense fermion field with all of the particle species of an attometer primordial black hole’s (PBH) high energy Hawking radiation spectrum. By extrapolating to Planck-sized PBHs, it is shown that although Planck-sized PBHs closely simulate the zero absorption requirement of white holes, the absorption probability is not truly zero, and therefore, thermodynamically, Planck-sized primordial black holes are not true white holes.

In this paper, we show how to obtain from a scalar superfield its first component via a similarity transformation. We prove that in $D=4$ the generators of this similarity transformation live in the enveloping algebra of supersymmetry while for $D=1$ they belong to the basic algebra.