Modern Physics Letters A

This work examines some aspects related to the existence of negative mass. The requirement for the partition function to converge leads to two distinct approaches. Initially, convergence is achieved by assuming a negative absolute temperature, which results in an imaginary partition function and complex entropy. Subsequently, convergence is maintained by keeping the absolute temperature positive while introducing an imaginary velocity. This modification leads to a positive partition function and real entropy. It seems the utilization of imaginary velocity may yield more plausible physical results compared to the use of negative temperature, at least for the partition function and entropy.

Ruppeiner scalar curvature can be considered as an empirical tool to explore the nature of interaction among the microstructures of black holes. In the extended phase space, the phase transitions and criticality are investigated for the dyonic black holes in an ensemble, where the electric potential ${\mathrm{\Phi }}_e$ is fixed. At first, we described the thermodynamic properties of dyonic black holes to investigate the $P-V$ criticality. Further, the Ruppeiner scalar curvature is calculated in an ensemble with fixed ${\mathrm{\Phi }}_e$ utilizing the fluctuation coordinates $(T,V)$. The behavior of interactions among the microstructures of the dyonic black holes in AdS is studied where the dominance of attractive or repulsive interaction is found to be dependent on the values of electric potential ${\mathrm{\Phi }}_e$.

In this work, we propose a parity-invariant Maxwell–Chern–Simons $\mathrm{\text{U}}(1)\times \mathrm{\text{U}}(1)$ model coupled with two charged scalar fields in $2+1$ dimensions, and show that it admits finite-energy topological vortices. We describe the main features of the model and find explicit numerical solutions for the equations of motion, considering different sets of parameters and analyzing some interesting particular regimes. We remark that the structure of the theory follows naturally from the requirement of parity invariance, a symmetry that is rarely envisaged in the context of Chern–Simons theories. Another distinctive aspect is that the vortices found here are characterized by two integer numbers.

Quantum signature has become a hot topic in the current research of digital signature schemes due to its unconditional security. As a special kind of digital signature, ring signatures are frequently employed in practical situations because of their superior anonymity. In this work, we propose a quantum ring signature scheme based on secret sharing that does not use entanglement states. To guarantee the complete security of the participants’ secret keys, the idea of secret sharing is incorporated into the quantum key distribution process during the key distribution stage. Each ring member contributes his private key share to the final verification formula through a recursive relationship throughout the signing and verification phases, and the verifier can utilize his private key share along with the user’s public key to confirm the ring members’ authenticity; The $\epsilon$-AS2U hash function is used to encrypt the ring signer’s identity during the entire signature process, which assures the signer’s identity’s complete anonymity, effectively protects the signer’s privacy, and is more in line with practical requirements.

The $\alpha$-decay and spontaneous fission (SF) half-lives for even–even isotopes of superheavy nuclei in the range $106\le Z\le 124$ are predicted using nuclear double-folding and Coulomb potentials. The $\alpha$-decay half-lives are computed based on WKB approximation for tunneling probability through potential barrier. The half-lives of SF have also been calculated using a semi-empirical relation constructed by Santhosh et al. [Nucl. Phys. A 832, 220 (2009)]. Our calculated half-lives of cold SF and $\alpha$-decay are compared with the available experimental data. This comparison indicates that our obtained half-lives are in good agreement with the available experimental data. The competition between $\alpha$-decay and SF is also analyzed in detail and the decay modes are predicted for the unknown cases. Variation of $\alpha$-decay and SF half-lives with mass number of the parent isotopes for each nucleus revealed the major role played with shell effect.

The connection between gravitational and inertial masses of compound objects (e.g. nucleons, nuclei, atoms, and molecules) in the presence of rapid internal motions of their constituent parts is considered. The equality of gravitational and inertial masses of such objects confirming the weak equivalence principle is proven provided that their moving constituent parts are confined. The result is very nontrivial because of a substantial difference between particle dynamics in noninertial frames and gravitational fields. Paradoxically, gravitational effects are different for the same particles moving in the closed box and in the free space. The gravitational and inertial masses are equal to the corresponding kinematic masses. In contrast, gravitational masses of ensembles of noninteracting moving particles cannot be introduced because the total gravitational forces acting on these ensembles do not correspond to their kinematic masses.