Modern Physics Letters A

We study signals of the weak and strong deflection gravitational lensings by an Extended Uncertainty Principle (EUP) black hole, which is based on a modified Heisenberg relation with an additional correction of position-uncertainty. Gravitational lensing observables, including positions, magnifications and differential time delays between lensed images, are obtained in both scenarios and analyzed for the supermassive black holes (SMBHs) in the Galactic Center (Sgr A*) and M87. We find that, for Sgr A*, measurements on the separation between the primary and secondary images in the weak deflection lensing and the apparent size of the photon sphere in the strong deflection lensing are two feasible ways to constrain EUP, imposing comparable lower bounds on the fundamental scale of EUP as $\sim$10¹⁰ m. For the SMBH in M87, measurements on strong deflection lensing observables are only available and they can give a much bigger lower bound as $\sim$10¹³ m. These results might provide hints for probing EUP black holes by gravitational lensings.

We explore the problem of charged perfect fluid spherically symmetric gravitational collapse in f(R, T) gravity (R is Ricci scalar and T is the trace of energy–momentum tensor). We have taken the interior boundary of a star as spherically symmetric metric filled with the charged perfect fluid. In order to study charged perfect fluid collapse, we have investigated the exact solutions of the Maxwell–Einstein field equations solutions using the most simplified form for f(R, T) model f(R, T) = R + 2$\lambda$T, where $\lambda$ is model parameter. This study involves the effects of charge as well as coupling parameter on collapse of a star. We studied the nature of trapped surfaces, apparent horizon and singularity structure in detail. It has been found that singularity is formed earlier than the apparent horizons, so the end state of gravitational collapse in this case is black hole.

This work aimed to investigate the production of ${}^{151}$Sm and ${}^{152,154,155}$Eu on natural Nd and Sm targets via particle accelerator because these radionuclides have the potential for use in nuclear battery technology such as betavoltaic batteries and radioisotope thermoelectric generators. Therefore, this work estimated cross-section curves for proton, deuteron, triton, helium-3, and alpha particles induced reactions in the energy range $E_{\mathrm{\text{particle}}}=100\to 1\mathrm{\text{MeV}}$. The activities and products of yield were simulated for all reaction processes under selected conditions, the particle beam current of 1 mA and the irradiation time of 24 h. Moreover, to understand the formations of ${}^{151}\mathrm{\text{Sm}}$ and ${}^{152,154,155}$Eu in the reaction processes, the appropriate energy region of the reactions by calculating the integral yield curves were determined. Based on the obtained results, determination of suitable targets, energy regions, and reaction processes were discussed by this work.

In this paper, new analytical obliquely propagating wave solutions for the time fractional extended Zakharov–Kuzetsov (FEZK) equation of conformable derivative are investigated. By using the main properties of the conformable derivative, the FEZK equation is transformed into integer-order differential equations, and the reduced equations are solved via the generalized exponential rational function method (GERFM). The shape and features for the resulting solutions are illustrated through three-dimensional (3D) plots and corresponding contour plots for various values of the free parameters.

In this paper, we obtain the quantum effective action for a scalar field which has been used for a special kind of symmetry breaking in gravity. Precisely by making use of some renormalization conditions, we calculate the one-loop path integral of canonical momentum. Moreover, we show that by introducing some new renormalization conditions, one can redefine the new degrees of freedom corresponding to a massive vector field.

The objective of this work is to explore a new parametric class of exact solutions of the Einstein field equations coupled with the Karmarkar condition. Assuming a new metric potential $e^{\lambda (r)}$ with parameter (n), we find a parametric class of solutions which is physically well-behaved and represents compact stellar model of the neutron star in Vela X-1. A detailed study specifically shows that the model actually corresponds to the neutron star in Vela X-1 in terms of the mass and radius. In this connection, we investigate several physical properties like the variation of pressure, density, pressure–density ratio, adiabatic sound speeds, adiabatic index, energy conditions, stability, anisotropic nature and surface redshift through graphical plots and mathematical calculations. All the features from these studies are in excellent conformity with the already available evidences in theory. Further, we study the variation of physical properties of the neutron star in Vela X-1 with the parameter (n).

¹²C isotope composing 3$\alpha$ cluster was investigated in this study. Therefore, ¹²C can be considered as a 3-body system. For studying the interactions in 3$\alpha$ clusters, a central potential was applied. Jacobi relative coordinates were also employed and center of mass motion was removed. In this paper, the Klein–Gordon (K–G) equation was solved using Nikiforov–Uvarov potential. At the end, the energy spectrum and wave function of isotope ¹²C were determined and the results were compared with the experimental data which showed good coincidence reflecting the success of our model in prediction.

The local curvature of the space produced by the Sun causes not only the perihelion precession of Mercury’s elliptical orbit, but also the variations of the whole orbit, in comparison with those predicted by the Newtonian theory of gravitation. Calculations show that the gravitational major-axis contraction of Mercury’s elliptical orbit is 1.3 km which can in principle be confirmed by the present astronomical distance measurement technology.

In this paper, we find the parafermion algebra of order $p$ expressed in terms of bilinear relation (commutator form). We find the correct Hamiltonian of parafermion of order $p$ by using the parasupersymmetry. Finally, we discuss the comparison of specific heats for several parafermions of order $p=1,2,3,4$.