Modern Physics Letters A

One of the possible ways to explain the observed flavor structure of fundamental particles is to include flavor symmetries in the theories. In this work, we investigate the rare charged lepton flavor violating (cLFV) decay process $(\mu \to e\gamma )$ in two of the low-scale ($\sim$TeV) seesaw models: (i) the Inverse seesaw (ISS) and (ii) Linear seesaw (LSS) models within the framework of $A_4$ flavor symmetry. Apart from the $A_4$ flavor symmetry, some other symmetries like $U{(1)}_X$, $Z_4$ and $Z_5$ are included to construct the Lagrangian. We use results from our previous work [M. R. Devi and K. Bora, A comparative study of type-II, inverse and linear seesaw mechanisms with $A_4$ flavor symmetry, presented at DAE HEP Symp., 2020, Jatni, Odisha; M. R. Devi and K. Bora, Mod. Phys. Lett. A 37, 2250073] where we computed unknown neutrino oscillation parameters within $3\sigma$ limits of their global best fit values, and apply those results to compute the branching ratio (BR) of the muon decay for both the seesaw models. Next we compare our results with the current experimental bounds and sensitivity limits of BR$(\mu \to e\gamma )$ as projected by various experiments, and present a comparative analysis that which of the two models is more likely to be tested by which current/future experiment. This is done for various values of currently allowed non-unitarity parameter. This comparative study will help us to pinpoint that which of the low-scale seesaw models and triplet flavon VEV alignments will be more viable and favorable for testing under a common flavor symmetry ($A_4$ here), and hence can help discriminate between the two models.

The process of $J/\psi \to \mathrm{\Lambda }\bar{\mathrm{\Lambda }}$ is studied using $1.0\times 10^{12}$ $J/\psi$ Monte Carlo (MC) events at $\sqrt{s}=3.097$ GeV with a fast simulation software at future Super Tau Charm Facility (STCF). The statistical sensitivity for CP violation is determined to be the order of ${𝒪}(10^{-4})$ by measuring the asymmetric parameters of the $\mathrm{\Lambda }$ decay. Furthermore, the decay of $J/\psi \to \mathrm{\Lambda }\bar{\mathrm{\Lambda }}$ also serves as a benchmark process to optimize the detector responses using the interface provided by the fast simulation software.

In this work, we find the asymptotic behavior for a commutative and noncommutative Mixmaster model in a Quantum Cosmology (QC) and semiclassical scenario, showing explicitly the calculus and applying the asymptotically equivalent functions that allow us to analyze the equivalence between Bianchi IX and Bianchi II models.

The thermodynamic properties of a non-interacting ideal hadron resonance gas (HRG) of finite volume have been studied in the presence of an external magnetic field. The inclusion of background magnetic field in the calculation of thermodynamic potential is done by the modification of the dispersion relations of the charged hadrons in terms of Landau quantization. The generalized Matsubara prescription has been employed to take into account the finite size effects in which a periodic (anti-periodic) boundary conditions is considered for the mesons (baryons). We find significant effects of the magnetic field as well as system size on the temperature dependence of energy density, longitudinal and transverse pressure especially in low temperature regions. The HRG is found to exhibit diamagnetism (paramagnetism) in the low (high) temperature region whereas the finite size effect is seen to strengthen the diamagnetic behavior of the medium.

We use a symmetrized Hamiltonian containing Dunkl operators to generate a Dunkl–Schrödinger equation with position-dependent mass. Our equation is shown to admit arbitrary-order Darboux transformations if the mass either has odd parity or is an inverse-square function. We construct the Darboux transformations and apply them to a Dunkl–Schrödinger system featuring a rational double well potential.

Quantum Fisher Information Matrix (QFIM) is a fundamental concept in quantum-theoretical measurement that emphasizes the importance of quantum Cramér–Rao bound in estimating quantum parameters. Many relationships have been discovered between QFIM and many recent areas of research in quantum information. These relationships indicate that QFIM is not just a concept in quantum metrology but is a fundamental quantity in quantum information. The ability to estimate parameters and describe the optimal induced conditions for the thermal state of the two-axis twisting model was examined. QFIM is used as an estimator for multiple parameters. We show that simultaneous estimation reduces the estimate of parameter variation, so the accuracy of simultaneously estimating parameters is much better than individually. Each parameter can be used to control the criterion to reduce the minimum differences between other parameters.

Recently, Cui et al. [Sci. China Phys. 62, 110311 (2019)] proposed a measurement-device-independent quantum key distribution (MDI-QKD) scheme based on high-dimensional encoding to increase the channel capacity of each individual photon. A secret key is shared among two legitimate parties via the help of a dishonest third-party (TP). They claimed that the proposed protocol can improve the drawback of the low-key generation rate that existed in the past MDI-QKD schemes. However, this study pointed out a loophole during the security check of TP. That is, the two legitimate participants merely use the corresponding qubit pairs that are both generated in the diagonal basis for the discussion, which leads to a potential attack that not only allows TP to avoid the security check but also creates partial inconsistency of key bits for both communicating sides. Fortunately, this problem can be fixed by a minor correction of the protocol.