Modern Physics Letters A

In this paper, we study a non-renormalizable $\mathrm{\text{U}}{(1)}_{B-L}$ extension of the Standard Model with $D_4$ and $Z_4$ symmetries accommodating the most recent neutrino data within the type-I seesaw mechanism. The two squared mass differences and three mixing angles can get the best-fit values while the leptonic Dirac CP phase is in $1\sigma$ range of the best-fit values for both normal and inverted orderings. The sum of active neutrino mass and the effective neutrino masses are, respectively, predicted to be $\sum m_{\nu }=60.03\text{meV}$, $〈m_{ee}〉=2.307\text{meV}$ and $〈m_{\beta }〉=8.903\text{meV}$ for normal ordering while $\sum m_{\nu }=101.20\text{meV}$, $〈m_{ee}〉=49.93\text{meV}$ and $〈m_{\beta }〉=49.95\text{meV}$ for inverted ordering, which are well consistent with the current experimental constraints.

The main motivation of our study is to explore Rényi holographic dark energy, Sharma–Mittal holographic dark energy, Rényi new agegraphic dark energy, and Sharma–Mittal new agegraphic dark energy in the context of generalized Rastall gravity with the two-fluid system, dark energy, and dark matter. In this regard, we have considered the scale factors into two distinct categories, one of which corresponds to the future singularity, whereas the other represents initial singularity. By employing future event horizon as infrared (IR)-cutoff, different cosmological quantities like deceleration parameter, equation of state (EoS) parameter are evaluated, and their ramifications have been described graphically. Analyzing the squared speed of sound, we have seen classically stable and unstable behavior for each of the considered models. Finally, we study ${\omega }_D$–${\omega }_D^{\prime }$ plane and find the thawing/freezing regions.

The concept of dark matter (DM) hypothesis comes out as a result from the input of the observed flat rotational velocity. With the assumption that the galactic halo is pseudo-spheroidal and filled with charged perfect fluid, we have obtained a solution which has inkling to a (nearly) flat universe, compatible with the modern day cosmological observations. Various other important aspects of the solution such as attractive gravity in the halo region and the stability of the circular orbit are also explored. Also, the matter in the halo region satisfies the known equation of state which indicates its non-exotic nature.

To describe $n+{}^{12}\mathrm{\text{C}}$ interactions with production of three $\alpha$-particles at incident neutron kinetic energy of 14 MeV in a nuclear (photo) emulsion, a Monte Carlo model is proposed for four channels of decay of an excited carbon-12 nucleus into three $\alpha$-particles. The Monte Carlo calculation results describe well the experimental data on the distribution of the angle between the three-dimensional momenta of all pairs of $\alpha$-particles in a collision event, on the distribution of the angle between the projections of the momentum vectors of all pairs of $\alpha$-particles in collision event on each of the coordinate planes, on the distribution of the sum of the kinetic energies of all pairs of $\alpha$-particles in a collision event, and the distribution of projections of the momenta of $\alpha$-particles on the coordinate planes. The best agreement of the Monte Carlo model results with the experimental data is achieved if the direct decay ${\mathrm{\text{C}}}^{12^{\ast }}\to 3\alpha$ and decay through the formation of an intermediate beryllium nucleus ${\mathrm{\text{C}}}^{12^{\ast }}\to \alpha +{\mathrm{\text{Be}}}^{8^{\ast }}\to 3\alpha$ are generated with equal probabilities, while the excitation energies of 3.04 MeV, 1.04 MeV, and 0.1 MeV for the beryllium nucleus are generated with relative weights of 75%, 15%, and 10%, respectively.

The elastic scattering cross-sections of ${}^{28}$Si projectile by ${}^{27}$Al, ${}^{28}$Si, ${}^{58}$Ni, ${}^{64}$Ni and ${}^{208}$Pb targets are analyzed using the double folding model based on the effective M3Y interaction which is known as the most popular density independent form. In the calculations of the double folding model, 16 different density distributions of ${}^{28}$Si nucleus are examined. A very good agreement between experimental data and theoretical results is obtained, and also the literature results support our results. In addition, dependence on incident energy, target atomic number and target mass number of the imaginary potential depth is studied, and new and global equations are proposed.

We have investigated the role of central depression parameter on the estimation of survival probability, the Coulomb excitation cross-sections and absorption effects of ${}^{80}\mathrm{\text{Kr}}+{}^{197}\mathrm{\text{Au}}$ system. The variation in central depression is found to be affecting all the above-mentioned quantities significantly. The survival probability and the Coulomb excitation cross-section are found to be decreasing with increase in $w$ while the absorption effects are found to be increasing.

Violation of the null energy condition plays an important role both in the general theory of relativity and quantum field theory in curved spacetimes. Over the years, it has been shown that the violation of the null energy condition leads to instability and violation of causality. In quantum field theory, violation of the energy condition also depends on the quantum states apart from the geometry of curved spacetime. Hence, the quantum effects play an important role in the violation of the null energy condition. We show that the set of all the coherent states does not violate the null energy condition. Further, we also show that under certain conditions, the null energy condition is violated either by a pure state or a mixed state. Furthermore, the dynamical violation of the null energy condition by the quantum states is also discussed here.