Modern Physics Letters A

The branching fractions of the decays $\tau \to a_1\pi {\nu }_{\tau }$, $\tau \to K_1\pi {\nu }_{\tau }$ and $\tau \to K_{1}K{\nu }_{\tau }$ are calculated in the framework of the extended $\mathrm{\text{U}}(3)\times \mathrm{\text{U}}(3)$ chiral Nambu–Jona-Lasinio model. There are no experimental data for these decays in the present time, thus the obtained results are considered as predictions. The comparison of these results to the theoretical results of other authors is carried out.

The neutron skin thickness of ⁴⁸Ca was deduced from the interaction cross-section by adopting a microscopic optical potential. The optical potential used was constructed by folding a chiral $g$ matrix and the Skyrme mean-field densities renormalized by considering the information of the interaction cross-section. The result was $R_{\mathrm{\text{skin}}}=0.139\pm 0.058$ fm.

For the inflaton field, we determine a new exact solution by using the Lie symmetry analysis. Specifically, we construct a second-order differential master equation for arbitrary scalar field potential by assuming that the spectral indices for the density perturbations $n_s$ and the scalar-to-tensor ratio $r$ are related as $n_s-1=h(r)$. Function $h(r)$ is classified according to the admitted Lie symmetries for the master equation. The possible admitted Lie symmetries form the $A_2$, $A_{3,2}$, $A_{3,3}$ and $sl(3,R)$ Lie algebras. The new inflationary solution is recovered by the Lie symmetries of the $A_{3,3}$ algebra. Scalar field potential is derived explicitly, while we compare the resulting spectral indices with the observations.

In this research, we have studied a flat Friedmann–Roberston–Walker (FRW) cosmological models with quark and strange quark matter in fractal gravity. We have assumed a fractal parameter $\omega \ne 0$ and the fractal function $v$ in the form of power law to obtain a deterministic solution of the modified field equations of the models. The solution of field equations is obtained in terms of Kummer’s function of first kind. The physical implications of the models are also discussed.

A few Euclidean wormhole configurations are presented using both the analytic and numerical solutions of the field equations in four-dimensional Robertson–Walker Euclidean background with Einstein–Gauss–Bonnet dilaton interaction. In one analytic solution we present transition from a wormhole to an exponential expansion with Lorentzian time $t$ using $\tau =it$ after passing through an era of oscillating Euclidean wormhole. The numerical solutions of the scale factor $a(\tau )$ show multiple local maxima and minima about a global minimum for inverse power law potentials, while for exponential potential the wormholes have a single minimum. An inflationary cosmic scenario away from the throat of the wormhole can be obtained from the Hubble parameter and deceleration parameter obtained by curve fit of $a(\tau )$ of the numerical solution invoking analytic continuation by $\tau =it$. The potential is also observed to decay sharply.

High-dimensional quantum communication plays an important role in long-distance quantum communication. It is shown that two-qubit quantum entanglement can be protected from amplitude damping decoherence. We study the effect of amplitude damping decoherence on two-qubit high-dimensional quantum entanglement. The negativity for high-dimensional quantum entanglement with or without quantum weak measurement and the reversal in amplitude damping decoherence are presented. We found that nonmaximally entangled state may have better performance than maximally entangled state in amplitude damping decoherence. Moreover, we show that arbitrary high-dimensional quantum entanglement can be protected from amplitude damping decoherence by weak measurement and the reversal. The results of our protocol are in agreement with previous analysis for the case of qubits and qutrits.

Ji et al. [Mod. Phys. Lett. A 34, 1950229 (2019)] and Fan et al. [Mod. Phys. Lett. A 37, 2250026 (2022)] proposed two-party quantum private comparison (QPC) protocols based on 7-qubit and 8-qubit states, respectively. However, these two QPC protocols did not consider third-party (TP) attacks. Therefore, this study focuses on TP attacks and demonstrates that the property of a 7-qubit or 8-qubit entanglement state is useless in this attack situation; that is, the participant wastes resources to maintain the qubits. For the same assumption environment proposed by Ji et al. and Fan et al., this study proposes an improvement and simplification protocol that allows participants to reach the goal of private comparison by using only classical computation and the classical communication channel without any entanglement state.