Modern Physics Letters A

Theoretical physicists generally prefer to modify the general theory of relativity rather than avoiding the successful approaches that have been offered to us. Hence, the rainbow formalism of gravity, which is one of the most studied quantum gravity candidates in literature, has recently gained importance in the field. In this study, the energy–momentum localization problem is discussed for the Taub universe within the framework of rainbow gravity. To achieve this goal, energy and momentum components are calculated by making use of diverse values of rainbow functions in the Einstein, Bergmann–Thomson, Landau–Lifshitz, and the Papapetrou prescriptions for the geometry under consideration. Except for the Landau–Lifshitz prescription, all prescriptions depend on the rainbow functions and the momentum components vanish. Graphical analysis is performed for all the energies obtained. Also, it is shown in limiting condition $f_1(\chi )\to 1,f_2(\chi )\to 1$ that the results are compatible with the ones obtained in the general relativity.

We consider the Jaynes–Cummings models (JCMs) of two identical two-level atoms interacting with a single mode of the Arik–Coon and Biedenharn–Macfarlane $q$-boson fields in a cavity. It is shown that there is a constant of motion, so-called the total number of excitation, which leads to decomposition of the total Hilbert space of $q$-deformed system into three invariant subspaces. So, we have the block diagonal structure with three blocks as the Hamiltonian matrices. The exact energy spectrum and eigenstates of the $q$-deformed models are obtained by diagonalizing each block. Assuming that the cavity fields and atoms are in thermal equilibrium, the partition function and thermal density matrix of the models are calculated. Finally, the influence of deformation parameters of the Arik–Coon and Biedenharn–Macfarlane $q$-oscillator light fields at low-temperatures on the entropy and internal energy of the Jaynes–Cummings models as well as on the atom–atom entanglement via the concurrence measure is analyzed.

A new multiparty measurement-device-independent quantum secret sharing (MDI-QSS) protocol is proposed based on entanglement swapping. All the measurement tasks are delegated to an untrusted party, eliminating all detector-side-channel loopholes. Only Einstein–Podolsky–Rosen (EPR) pairs, single photons and Bell-state measurements are required irrespective of the number of participants. Compared with existing MDI-QSS protocols, no additional unitary operations or Greenberger–Horne–Zeilinger (GHZ)-state measurements are needed. Our protocol is feasible experimentally and holds inspiring potential for the application in practical multiparty quantum communication networks.

We have presented the Big Rip singularity in $f(R,T)$ gravity with tilt congruences and creation field. We have solved the field equations by considering a conformally flat universe and the condition $B=A^n$, where $n$ is a constant. The solutions of the field equations have also been investigated by using the method of [J. V. Narlikar and T. Padmanabhan, Phys. Rev. D 32, 1928 (1985)] in which the creation field $C$ is a function of time $t$. Some geometric aspects of the model are also discussed by using MATLAB.

As a function of the barrier height, center-of-mass energy, Coulomb interaction parameter and $Z^2/A$, a new empirical formula for the astronomical $S$-factor has been proposed. Around 14 fusion reactions using ${}^{46,48,50}$Ti as projectiles were taken into consideration for various targets, producing compound nuclei with atomic and mass number ranges of $44\le Z\le 104$ and $92\le A\le 258$, respectively. The geometric factor, Gamow–Sommerfield factor and empirical $S$-factor formulas have been used to determine the fusion cross-sections. Compared to Wong’s formula, this study shows a better agreement with the available experiments except for the ${}^{48}\mathrm{\text{Ti}}+{}^{122}\mathrm{\text{Sn}}$ and ${}^{48}\mathrm{\text{Ti}}+{}^{166}\mathrm{\text{Er}}$ fusion reactions. When employed to correlate with the experimental data on titanium-induced fusion reactions, this study yields a lower standard deviation value than Wong’s formula except for the fusion reactions leading to the formation of compound nuclei ${}^{170}$Hf and ${}^{214}$Th.

Doubly differential transverse momentum spectra of strange mesons $K^{\ast }{(892)}^0$ and $K^{\ast }{(892)}^{\pm }$ within rapidity interval of $|y|<0.5$ are studied by using Monte Carlo event generators in pp, pPb and PbPb collisions at different center-of-mass energies. The predictions of simulations are compared to the ALICE data. The fitting of doubly differential transverse momentum spectra of ALICE data is performed by using Tsallis distribution function. To check the quality of the fitting, chemical potential is also set to zero value. The extracted values of the non-extensive parameter ($q$), a chemical potential $\mu$ and effective Tsallis temperature $T$ for different particle species have been obtained from the thermodynamically consistent Tsallis distribution function. It is observed that the effective Tsallis temperature increases at different center-of-mass energies. The predictions of the MC event generators, i.e. PYTHIA8 CR and HIJING 2.0 are compared to the ALICE data, deviations are observed which may be due to the reshuffling of parton colors and string fragmentation.

The Koopman–von Neumann (KvN) mechanics is an approach that was formulated long ago to answer the question regarding the existence of a Hilbert space representation of classical mechanics. KvN mechanics is a non-relativistic theory, and it is not clear how spin can be included in it, since spin is widely regarded as a relativistic property. Cabrera et al., in Eur. Phys. J. Spec. Top. 227, 2195 (2019) argued that the Spohn equation [Spohn, Ann. Phys. 282, 420 (2000)] is the correct classical framework for the Koopman–von Neumann theory corresponding to the Dirac equation. However, after Lévy-Leblond’s seminal work on this topic, it became clear that spin naturally arises also from the Galilean invariant wave equations, without any need of relativistic considerations. Inspired by this, we propose another possibility of including spin in the KvN formalism: the Lévy-Leblond equation in the Koopman–von Neumann formalism can be obtained as a null reduction of the massless Dirac equation in the Eisenhart–Duval lift metric. To illustrate the idea, we implement it for a one-dimensional classical system without magnetic interactions.

Here, we comment on the paper “Numerical study of the SWKB condition of novel classes of exactly solvable systems.” [Y. Nasuda and N. Sawado, Mod. Phys. Lett. A 36, 2150025 (2021).] We show that it misrepresents our prior work [J. Bougie, A. Gangopadhyaya and C. Rasinariu, J. Phys. A: Math. Theor. 51, 375202 (2018)], and clarify this misunderstanding.