Modern Physics Letters A

The 2S $B_c$ states observed by ATLAS, CMS and LHCb Collaborations are discussed. The observation perspectives of $B_c^{\ast }$, 2P wave, 3P wave and D wave states of $B_c$ at LHC experiments are estimated.

A few years ago, the use of standard functional manipulations was demonstrated to imply an unexpected property satisfied by the fermionic Green’s functions of QCD, and called effective locality. This feature of QCD is non-perturbative as it results from a full integration of the gluonic degrees of freedom. In this paper, at eikonal and quenching approximation at least, the relation of effective locality to dynamical chiral symmetry breaking is examined.

The cross-section of $e^{+}{e}^{-}\to K^{+}{K}^{-}J/\psi$ has been measured by BESIII experiment, two enhancements are seen around 4.2 GeV and 4.5 GeV. We try to fit the cross-section with coherent sum of two Breit–Wigner functions, the fit results show $e^{+}{e}^{-}\to K^{+}{K}^{-}J/\psi$ line shape can be described by $Y(4220)$ and a new structure around 4.5 GeV, also can be described by the known charmonium $\psi (4160)$ and $\psi (4415)$. Based on current data, we cannot distinguish which explanation is right. More measurements around 4.2 GeV and 4.5 GeV are desired to improve the understanding of the structures in $e^{+}{e}^{-}\to K^{+}{K}^{-}J/\psi$.

In this paper, we propose a novel model of scalar field fuzzy dark matter based on Stueckelberg theory. Dark matter is treated as a Bose–Einstein condensate of Stueckelberg particles and the resulting cosmological effects are analyzed. Fits are understood for the density and halo sizes of such particles and comparison with existing models is made. Certain attractive properties of the model are demonstrated and lines for future work are laid out.

In this paper, we study thermodynamics of the regular black holes with Bardeen–AdS black hole. The cut-off radius which is the minimal radius of the stable Bardeen–AdS black hole has been obtained from temperature and heat capacity analysis, respectively. Moreover, the thermodynamical stability of the Bardeen–AdS black hole is learned by the Gibbs free energy and the heat capacity. In this work, we find similar properties to the van der Waals liquid-gas system.

We compute the quantum information metrics of a thermal CFT on ${ℝ}^{1,1}$ perturbed by the scalar primary operators of conformal dimensions $\mathrm{\Delta }$ = 3, 4, 5, 6. In particular, we assume that the Hamiltonians of the mixed states commute with each other and the temperature is fixed. Under these conditions, the evaluation is analogous to the pure state case. Then we apply the method of A. Trivella [Class. Quantum Grav. 34, 105003 (2017)] to calculate the mixed state information metric for the scalar primary operator of conformal dimension $\mathrm{\Delta }$ = 4 holographically, and reproduce exactly the result in the CFT₂ by our approach.

In this paper, we study the importance of configurations of the observer’s congruences in the analysis of the dynamical properties of planar relativistic systems in f(R) geometry. To this end, we assume a relativistic distribution of matter contents whose gravitational effects would produce planar geometry. In order to relate matter ingredients seen by tilted and non-tilted observers, we have calculated particular theoretical relationships. After calculating dynamical, Ellis and transport equations, the pace of gravitational collapse as well as the corresponding stable epochs of the systems are discussed. The instability of non-comoving reference frame has been elaborated in a particular background.

A Riccati equation rational expansion (RERE) method is implemented to attain solutions of nonlinear partial differential equations (NLPDEs). Subsequently, the technique is used to attain families or sets of nonlinear solutions for the third extended fifth-order nonlinear equation and the generalized (2 + 1)-dimensional Boussinesq equation. By the use of the RERE method, exciting and new forms of solution such as rational solitary wave solutions, solitary wave solutions and periodic solitary wave solutions are obtained. Some of the solutions are demonstrated graphically with specific values assigned to the parameters. It is worth noting that the application of this method is very effective and reliable.

We propose a new two-party quantum key agreement (QKA) protocol using five-qubit Brown states. One-way quantum transmission can be realized by merging Brown states and decoy photons randomly. The security of this protocol is shown to resist the outsider attack and participant attack over the ideal channel. Some methods are also proposed to ensure its security in noisy and lossy quantum channel. Finally, we generalize it and propose a multi-party QKA protocol based on Brown states.