Modern Physics Letters A

In this paper, we give a brief account of the history of neutrino, and how that most aloof of all particles shaped our search for a theory of fundamental interactions ever since it was theoretically proposed. We introduce the necessary concepts and phenomena in a nontechnical language aimed at a physicist with some basic knowledge of quantum mechanics. In showing that neutrino mass could be the door to new physics beyond the Standard Model, we emphasize the need to frame the issue in the context of a complete theory, with testable predictions accessible to present and near future experiments. We argue in favor of the minimal Left–Right symmetric theory as the strongest candidate for such theory, connecting neutrino mass with parity breakdown in nature. This is the theory that led originally to neutrino mass and the seesaw mechanism behind its smallness, but even more important, the theory that sheds light on a fundamental question that touches us all: the symmetry between left and right.

Measurements of disappearance channel of long baseline accelerator-based experiments (like NO$\nu$A) are inflicted with the problem of octant degeneracy. In these experiments, the mass hierarchy (MH) sensitivity depends upon the value of CP-violating phase ${\delta }_{\mathrm{\text{CP}}}$. Moreover, MH of light neutrino masses is still not fixed. Also, the flavor structure of fermions is yet not fully understood. We discuss all these issues in a highly predictive, low-scale inverse seesaw (ISS) model within the framework of $A_4$ flavor symmetry. Recent global analysis has shown a preference for normal hierarchy and higher octant of ${𝜃}_{23}$, and hence we discuss our results with reference to these, and find that the vacuum alignment of $A_4$ triplet flavon $(1,-1,-1)$ favors these results. Finally, we check if our very precise prediction on $m_{ee}$ and the lightest neutrino mass falls within the range of sensitivities of the neutrinoless double beta decay $(0\nu \beta \beta )$ experiments. We note that when octant of ${𝜃}_{23}$ and MH is fixed by more precise measurements of future experiments, then through our results, it would be possible to precisely identify the favorable vacuum alignment corresponding to the $A_4$ triplet field as predicted in our model.

Working in the framework of generalized statistics, the problem of establishing third law of thermodynamics in the black hole physics is studied by focusing on Schwarzschild black hole which easily and clearly exposes the violation of this law in the common approach based on Bekenstein entropy. Additionally, it is addressed that some inconsistencies between the predictions of quantum field theory and thermodynamics about the black hole temperature may be reconciled by using the thermodynamics laws in order to broaden energy definition. It claims that thermodynamics should be employed as a powerful tool in looking for more comprehensive energy definitions in high-energy physics, still mysterious.

In the framework of general relativity (GR) and teleparallel equivalent to GR (TEGR), we investigate the energy–momentum localization of a stringy charged black hole by using Bergman–Thompson’s prescription and the Papapetrou’s prescription. Moreover, we investigate the gravitational energy–momentum (GEM) in TEGR. Our results are consistent with the results of previous studies. Finally, we calculate the GEM flux and gravitational center of mass in TEGR.

The properties of hybrid stars are studied via the hybrid EOSs that are compatible with astrophysical observables. These hybrid EOSs are constructed by interpolating between hadronic EOS at lower densities and the quark EOS at higher densities. The BSR6 EOS derived from the RMF model is adopted as the hadronic EOS, while the quark EOS is calculated via a quasiparticle model. The maximum masses obtained from the hybrid EOSs are larger than $2M_{\odot }$, and the tidal deformabilities for $1.4M_{\odot }$ hybrid stars are smaller than 800. The combined tidal deformability $\tilde{\mathrm{\Lambda }}$ is a monotonically increasing function of mass ratio $\eta$ for both hybrid EOSs and hadronic EOS, and it depends weakly on $\eta$. The results of all hybrid EOSs can strictly satisfy the constraint of $70<\tilde{\mathrm{\Lambda }}<720$ and the mass and radius constraints from the newest joint analysis of NICER, XMM-Newton and GW170817 data.

Owing to the advantages of entanglement, in this work, an efficient and simple quantum sharing of two unknown state (QSTUS) protocol based on a six-qubit entangled state as the quantum channel is proposed. During the procession of the protocol, sender Alleyn possesses two unknown quantum states, at the same time, she wishes her four agents to share her quantum states. Hence, Alleyn implements two Bell basis measurements on her qubits, meanwhile the appointed controllers make a single-qubit measurement on her own qubit. Applying the suitable unitary operations, the state receivers can recover the original states. Analysis shows that only if all agents cooperate with each other, the proposed protocol QSTUS will be realized easily and successfully.

Recently, Fan et al. [Mod. Phys. Lett. A 36, 2150223 (2021)] presented a generalized Clauser–Horne–Shimony–Holt (CHSH) inequality, to identify $N$-qubit Greenberger–Horne–Zeilinger states. They showed an interesting phenomenon that the maximal violation of the generalized CHSH inequality is robust under some specific noises. In this work, we map the inequality to the CHSH game, and consequently to the CHSH* game in a single-qubit system. This mapping provides an explanation for the robust violations in $N$-qubit systems. Namely, the robust violations, resulting from the degeneracy of the generalized CHSH operators correspond to the symmetry of the maximally entangled two-qubit states and the identity transformation in the single-qubit game. This explanation enables us to exactly demonstrate that the degeneracy is $2^{N-2}$.