Modern Physics Letters A

The kinematical characteristics of distinct infalling homothetic fields are discussed by specifying the transverse subspace of their generated congruences to the energy–momentum deposit of the chosen gravitational system. This is pursued through the inclusion of the base manifold’s cotangent bundle in a generalized Raychaudhuri equation and its kinematical expressions. Exploiting an electromagnetic energy–momentum tensor as the source of non-gravitational effects, I investigate the evolution of the mentioned homothetic congruences, as they fall onto a Reissner–Nordström black hole. The results show remarkable differences to the common expectations from infalling congruences of massive particles.

We investigate lump-like solutions in models described by a single real scalar field with non-polynomial interactions in (1, 1) dimensions. We start with a model that supports kink-like solutions and then use the deformation procedure to obtain families of models with hyperbolic interactions. The results show that depending on the values of the parameters, the models can support lump-like and kink-like solutions. We illustrate our findings, constructing new models and examining their solutions, energy densities, stability potentials and zero modes.

We investigate the finite-temperature and zero quark chemical potential QCD chiral phase transition of strongly interacting matter within the two-flavor Nambu–Jona-Lasinio (NJL) model as well as the proper time regularization. We use two different regularization processes, as discussed in Refs. 36 and 37, separately, to discuss how the effective mass M varies with the temperature T. Based on the calculation, we find that the M of both regularization schemes decreases when T increases. However, for three different parameter sets, quite different behaviors will show up. The results obtained by the method in Ref. 36 are very close to each other, but those in Ref. 37 are getting farther and farther from each other. This means that although the method in Ref. 37 seems physically more reasonable, it loses the advantage in Ref. 36 of a small parameter dependence. In addition, we also, find that two regularization schemes provide similar results when T $<$ 100 MeV, while when T is larger than 100 MeV, the difference becomes obvious: the M calculated by the method in Ref. 36 decreases more rapidly than that in Ref. 37.

Quantum secure direct communication allows one participant to transmit secret messages to another directly without generating a shared secret key first. In most of the existing schemes, quantum secure direct communication can be achieved only when the two participants have full quantum ability. In this paper, we propose two semi-quantum secure direct communication protocols to allow restricted semi-quantum or “classical” users to participate in quantum communication. A semi-quantum user is restricted to measure, prepare, reorder and reflect quantum qubits only in the classical basis $\{|0〉,|1〉\}$. Both protocols rely on quantum Alice to randomly prepare Bell states, perform Bell basis measurements and publish the initial Bell states, but the semi-quantum Bob only needs to measure the qubits in classical basis to obtain secret information without quantum memory. Security and qubit efficiency analysis have been given in this paper. The analysis results show that the two protocols can avoid some eavesdropping attacks and their qubit efficiency is higher than some current related quantum or semi-quantum protocols.

We propose a renormalizable T′ flavor model based on the $\mathrm{\text{SU}}{(3)}_C\times \mathrm{\text{SU}}{(3)}_L\times \mathrm{\text{U}}{(1)}_X\times \mathrm{\text{U}}{(1)}_{{ℒ}}$ gauge symmetry, consistent with the observed pattern of lepton masses and mixings. The small masses of the light active neutrinos are produced from an interplay of type I and type II seesaw mechanisms, which are induced by three heavy right-handed Majorana neutrinos and three $\mathrm{\text{SU}}{(3)}_L$ scalar antisextets, respectively. Our model is only viable for the scenario of normal neutrino mass hierarchy, where the obtained physical observables of the lepton sector are highly consistent with the current neutrino oscillation experimental data. In addition, our model also predicts an effective Majorana neutrino mass parameter of $m_{\beta }\sim 1.41541\times 10^{-2}$ eV, a Jarlskog invariant of the order of $J_{\mathrm{\text{CP}}}\sim -0.032$ and a leptonic Dirac CP violating phase of $\delta =238^{\circ }$, which is inside the $1\sigma$ experimentally allowed range.

Mazharimousavi and Halilsoy [S. H. Mazharimousavi and M. Halilsoy, Mod. Phys. Lett. A 31, 1650192 (2016)] recently proposed wormhole solutions in f(R)-gravity that satisfy energy conditions but are unstable. We show here that stability could still be achieved for thin-shell wormholes obtained by gluing the wormholes in f(R)-gravity with the exterior Schwarzschild vacuum. Using the new geometrical constraints from thin-shell “mass” and from external “force” developed by Garcia, Lobo and Visser, we demarcate and analyze the stability regions.

The recently introduced by us, two- and three-parameter (p, q)- and (p, q, $\mu$)-deformed extensions of the Heisenberg algebra were explored under the condition of their direct link with the respective (nonstandard) deformed quantum oscillator algebras. In this paper, we explore certain Hermitian Hamiltonians build in terms of non-Hermitian position and momentum operators obeying definite $\eta$(N)-pseudo-hermiticity properties. A generalized nonlinear (with the coefficients depending on the particle number operator N) one-mode Bogoliubov transformation is developed as main tool for the corresponding study. Its application enables to obtain the spectrum of “almost free” (but essentially nonlinear) Hamiltonian.

The study of the baryon–antibaryon pair production from the charmonium states provides a favorable test and an input for the perturbative quantum chromodynamics calculation. Based on a Monte Carlo study via a single tag baryon strategy, a clear observation of $\psi$(3686)$\to \mathrm{\Xi }$(1530)$\bar{\mathrm{\Xi }}$(1530)⁰ is predicted at BESIII with the current 3.08$\times$10⁶ $\psi$(3686) dataset. The averaged precision of the $\alpha$ parameters in the decay angular distribution formula is estimated as 0.25, and is not effective to separate the theoretical predictions. It will be an opportunity to distinguish them with 3.0$\times$10⁹ $\psi$(3686) events taken by BESIII detector in the next few years.

Stueckelberg QED with massive photon is known to be renormalizable. But the limit of the mass going to zero is interesting because it brings the resolution to infrared questions through the role of Stueckelberg field at null infinity in addition to providing new asymptotic symmetries. Such symmetries facilitate the soft photon theorems also.

It is known that wormhole geometry could be found solving the Einstein field equations by tolerating the violation of null energy condition (NEC). Violation of NEC is not possible for the physical matter distributions, however, it can be achieved by considering distributions of “exotic matter”. The main purpose of this work is to find generating functions comprising the wormhole-like geometry and discuss the nature of these generating functions. We have used the Herrera et al. [Phys. Rev. D 77, 027502 (2008)] approaches of obtaining generating functions in the background of wormhole spacetime. Here we have adopted two approaches for solving the field equations to find wormhole geometry. In the first method, we have assumed the redshift function f(r) and the shape function b(r) and solve for the generating functions. In another attempt, we assume generating functions and redshift functions and then try to find shape functions of the wormholes.