International Journal of Modern Physics A

In this paper, we examine the correlation functions associated with intensity interferometry and gravito-optics of gravitational wave (GW) signals from compact binary coalescences (CBC). Previous theoretical studies of the gravito-optics of GWs have concentrated on the characterization of both the classical and the nonclassical properties of signals from cosmological sources in the early Universe. These previous works assume a periodic signal similar to the signals studied widely in optics and quantum optics and do not apply to transient signals. We develop the gravito-optics of intensity correlations for descriptions of the detection of transient signals from CBC and apply these methods to calculate the two-point intensity correlations for the GW discovery. We also discuss the necessary theoretical work required for the description of the quantum gravito-optics of intensity correlations in the detection of signals from binary inspirals.

Inspired by the pronounced effect of gravity’s Rainbow on black hole thermodynamics, entropy relations and bounds have been investigated for $d$-dimensional Reissner–Nordström (RN) black hole in the framework of Rainbow gravity. Basic thermodynamic properties of the black hole have been derived for the event horizon and Cauchy horizon. Except for the horizon radius, they all crucially depend on the Rainbow functions. Bounds of the aforesaid thermodynamic quantities have been deduced for both horizons. Analyzing the specific heat capacity, stability conditions have been obtained. Also, the extremal phase of the black hole has been explored. Further, a comparative study has been carried out to distinguish between the effects of Rainbow gravity model parameters on the entropy bound by considering different Rainbow gravity functions. For massless scalar perturbation, quasinormal modes have been computed using modified WKB approach. We have investigated the quantum correction of the black hole in a Rainbow gravity background to obtain the effects of Extended Uncertainty Principle (EUP) and Generalized Uncertainty Principle (GUP) parameters. We have derived the Hawking temperature, specific heat, entropy and remnant masses of the black hole in the Extended General Uncertainty Principle (EGUP) framework, and with the help of graphical methods, we have compared our findings.

In our work, we compute the 4-dimensional Einstein–Gauss–Bonnet gravity black hole solution by applying the Newman–Janis approach and also examine the Hawking temperature. The generalized uncertainty principle (GUP) is applied to compute the Lagrangian field equation and by using the semi-classical phenomenon, we analyze the modified Hawking temperature. By taking into account the graphical analysis, we check the stable conditions of the black hole with the influence of rotation parameter, charged parameter and quantum gravity parameter. Furthermore, we compute the logarithmic entropy corrections in the background of corrected temperature and standard entropy for corresponding black hole. We study the behavior of different thermodynamics quantities like Helmholtz free energy, internal energy, Gibbs free energy and heat capacity under these fluctuations. In our analysis, we note that these corrections enhance the stability of this system, so, under the effects of these corrections, the considered geometry becomes more stable.

We present a simple algebraic method for the analytic continuation of harmonic sums with integer real or purely imaginary indices near negative and positive integers. We provide a MATHEMATICA code for exact expansion of harmonic sums in a small parameter near these integers. As an application, we consider the analytic continuation of the anomalous dimension of twist-1 operators in the ABJM model, which contains nested harmonic sums with purely imaginary indices. We found that in the BFKL-like limit the result has the same single-logarithmic behavior as in ${𝒩}=4$ SYM and QCD, however, we did not find a general expression for the “BFKL Pomeron” eigenvalue in this model. For the slope function, we found full agreement with the expansion of the known general result and give predictions for the first three perturbative terms in the expansion of the next-to-slope function. The proposed method of analytic continuation can also be used for other generalization of nested harmonic sums.

In this paper, we constructed characteristic identities for the 3-split (polarized) Casimir operators of simple Lie algebras in the adjoint representations $ad$ and deduced a certain class of subrepresentations in ${ad}^{\otimes 3}$. The projectors onto invariant subspaces for these subrepresentations were directly constructed from the characteristic identities for the 3-split Casimir operators. For all simple Lie algebras, universal expressions for the traces of higher powers of the 3-split Casimir operators were found and dimensions of the subrepresentations in ${ad}^{\otimes 3}$ were calculated. All our formulas are in agreement with the universal description of (irreducible) subrepresentations in ${ad}^{\otimes 3}$ for simple Lie algebras in terms of the Vogel parameters.

By assuming there exist three massive nondegenerate Majorana neutrinos, it is possible to describe neutrino mixing with a residual, unbroken discrete Klein subgroup of a larger spontaneously broken flavor symmetry group. Motivated by forthcoming measurements of leptonic CP violation, we revisit this framework by applying group presentation rules to it. We develop a method that is able to reproduce all previous results in the literature and may also hint at a possible group theoretical origin of CP violation in the Klein symmetry elements. This is due to the explicit appearance of a phase in them. However, for the cases considered in this analysis, it turns out that this phase can be removed. Still, this new method warrants further study.

This paper is motivationally based on the study revealing the characteristics of Acoustic Schwarzschild BHs in respect of particle dynamics, and weak gravitational plasma lensing. We discuss the particle dynamics by studying the effective potential, ISCO, for massive particle and photon motion. We consider the weak gravitation field to study the gravitational lensed photons. This purpose of lensing is served by taking under consideration three fields of plasma uniform plasma, singular isothermal sphere and a nonsingular isothermal sphere. Each field is separately incorporated to calculate the plasma deflection angle, which is further utilized in the image magnification associated with the source brightness for uniform plasma and singular isothermal sphere as a selective case. All the obtained results are compared with the Schwarzschild black hole case as a standard.

Consider two free Hamiltonians for the same scalar field with two different masses. We find a squeeze operator which maps the ground state of one to the other. The operator is described in both the Dirac and also the Schrödinger wave functional formalisms for quantum field theory. We conjecture that this construction can be generalized to obtain operators which map between distinct topological sectors in the same theory.

We investigate inflationary models in $f(R,T)$ modified gravity with a kinetic coupling term ${\omega }^2{G}^{\mu \nu }{\partial }_{\mu }\varphi {\partial }_{\nu }\varphi$ having a positive factor needed to remove the ghosts. Taking $f(R,T)=R+2\beta T$, we calculate and analyze the relevant observable quantities including the spectral index $n_s$ and the tensor-to-scalar ratio $r$ using the slow-roll approximations. Concretely, we consider two scenarios described by the decoupling and the coupling behaviors between the scalar potential and the $f(R,T)$ gravity via the moduli space by dealing with two potentials being the quartic one $V(\varphi )=\lambda {\varphi }^4$ and the small field inflation $V(\varphi )=V_0(1-{(\frac{\varphi }{\mu })}^{\alpha })$. For the quartic inflation model, we consider a decoupling behavior. For the small field inflation, however, we present the parameter decoupling and coupling scenarios. For both scenarios, we compute and inspect $n_s$ and $r$ showing interesting results. For three different values of the number of e-folds $N=60,65$ and 70, we find that the coupling between $f(R,T)$ and the scalar potential via the moduli space provides an excellent agreement with the observational findings. In the last part of this work, we provide a possible discussion on the amplitude of the scalar power spectrum needed to provide a viability of the proposed theory. Considering the second potential form in the parameter coupling scenario, we find acceptable values in certain points of the moduli space.

In recent years, many tetraquarks and pentaquarks have been discovered by various experimental groups and $X(3872)$, $Z_c(3900)$, $X(4430)$, $P_c^{+}(4312)$, $P_c^{+}(4457)$ are some of the interesting observed tetraquark and pentaquark states. The Regge trajectories of some such states are studied in view of the flux tube model of hadrons with finite quark masses. The effect of flux tube (or string) length variation on the Regge trajectories of these states is analyzed in detail. It is observed that for a fixed angular momentum, the string length has a constant value. Some other states are also proposed and the results obtained are then compared with the studies by others. Our findings correspond rather well with those of other researchers and with those of the experiment.