Modern Physics Letters A

According to the Leutwyler–Smilga relation, in Quantum Chromodynamics (QCD), the topological susceptibility vanishes linearly with the quark masses. Calculations of the topological susceptibility in the context of lattice QCD, extrapolated to zero quark masses, show a remnant nonzero value as a lattice artefact. Employing the Atiyah–Singer theorem in the framework of Symanzik’s effective action and chiral perturbation theory, we show the validity of the Leutwyler–Smilga relation in lattice QCD with lattice artefacts of order a² in the lattice spacing a.

We calculate the mass and residue of the newly observed ${\mathrm{\Omega }}_c(3000)$ and ${\mathrm{\Omega }}_c(3066)$ states with quantum numbers $J^P={\frac{1}{2}}^{-}$ and ${\frac{3}{2}}^{-}$ within QCD sum rules. The calculation is carried out by using the general form for interpolating current for $J=\frac{1}{2}$ baryon. Our predictions on masses are in good agreement with the experimental results.

In this paper, by applying the direct symmetry method, we obtain the symmetry reductions, group invariant solutions and some new exact solutions of the Bogoyavlenskii equation, which include hyperbolic function solutions, trigonometric function solutions and power series solutions. We also give the conservation laws of the Bogoyavlenskii equation.

In this paper, for the first time in the context of time orbiting potential (TOP) trap, the necessary and sufficient conditions for the adiabatic evolution of weak field seeking states have been quantitatively examined. It has been well accepted since decades that adiabaticity has to be obeyed by the atoms for successful magnetic trapping. However, we show, on the contrary, that atoms can also be confined beyond the adiabatic limit. For the demonstration, we have considered a toy model of a single weak field seeking atom in its ground state and have calculated its survival probability inside a TOP trap. Our findings open new possibilities to relax the restrictions of atom trapping in laboratories.

The aim of this paper is to study the gravitational collapse of charged cylindrical star in $f({𝒢})$ gravity. For this purpose, we derive dynamical equations by applying Misner–Sharp formalism and examine the effects of effective pressure and charge on the collapse rate. We also construct a relationship between matter variables, Gauss–Bonnet (GB) terms, and the Weyl tensor. For the constant value of $f({𝒢})$, it is found that spacetime is conformally flat if and only if the energy density is homogeneous. We conclude that the rate of collapse slows down in $f({𝒢})$ gravity due to anti-gravitational effects.

The description of the accelerated phases for the current and primordial cosmos has been obtained in the framework of Rényi cosmology. The results show that corrections to the Friedmann equations, originated from differences between Rényi and Bekenstein entropies, can describe both the current accelerated and inflationary eras. The effects of these corrections can be appointed to a hypothetical fluid which is classically unstable. Although inflation can be obtained in Rényi cosmology as the vacuum solution, the values found for the parameters of the hypothetical fluid which supports the current accelerated and primary inflationary cosmos differ from each other.

Recent observations of Stephan’s Quintet (SQ) gave new indications on its formation scenario. Older formation and role of NCG 7317 should be considered in revised numerical models of the compact group. Velocities of group members to recreate are estimated from redshift measurements. Several effects contribute to observed redshifts and a new effect is predicted to be the result of the gravitational interaction between photons and constant magnetic fields creating gravitational waves. The energy carried by these waves is manifested as redshifts of the photons. Cosmological simulation data are used to prove the significant contribution of our effect. The analysis of synthetic observations created from those simulations has shown that redshifts of SQ members could be misinterpreted as caused only from Doppler Effect. The revised models of the group should consider a new method to recreate the formation scenario based on redshift patterns and not mis-estimated velocities.

The extension of exponential rational function method is obtained to construct a series of exact solutions for higher-dimensional Broer–Kaup–Kupershmidt (BKK) dynamical system. New and general solutions are found. The solutions reported in this work are kink solutions, anti-kink solutions and bright solutions. They are expressed in terms of rational exponential functions. A confrontation of our results with the well-known results are done and it comes from this study that the solutions obtained here are new. The mathematical method applied to search for our solutions can be used for other nonlinear partial differential equations. The graphics of the obtained solutions in this paper are shown.

It is found that the controlled quantum secure direct communication (CQSDC) based on a seven-qubit entangled state protocol [S. K. Wang, X. W. Zha and H. Wu, Int. J. Theor. Phys. 57, 48 (2018)] can be passively attacked. That is to say, this protocol has the security loophole of information leakage. To be specific, the first bit of the sender’s two-bit message can be deduced by an attacker Eve according to the first and the third bits of Alice’s announcement and the first bit of the controller Charlie’s announcement. Then, a way to fix this loophole is discussed.