Modern Physics Letters A

The magnetized strange quark matter (MSQM) solutions are obtained for a Marder type universe using constant deceleration parameter. The exact solutions of field equations are obtained for f(R,T) = R + 2f(T) model given by [T. Harko et al., Phys. Rev. D 84, 024020 (2011)] with cosmological term. Also, we have obtained General Relativity (GR) solutions for MSQM distributions. For $t\to \infty$, we get the dark energy model, i.e. $p\to -B_c$, $\rho \to B_c$ and $\omega =-1$. However, for $t\to \infty$, we find the cosmological constant $\mathrm{\Lambda }$ as negative in f(R,T) theory and GR. These results agree with [S. Aygün et al., Astrophys. Space Sci. 361, 380 (2016); C. Aktaş and S. Aygün, Chinese J. Phys. 55, 71 (2017); P. K. Sahoo et al., Mod. Phys. Lett. A 32, 1750105 (2017)] in f(R,T) theory. The physical consequences of our obtained models are discussed at the end.

This paper discusses three matter-of-principle methods for measuring the general relativity correction to the Newtonian values of the position of collinear Lagrangian points L₁ and L₂ of the Sun–Earth-satellite system. All approaches are based on time measurements. The first approach exploits a pulsar emitting signals and two receiving antennas located at L₁ and L₂, respectively. The second method is based on a relativistic positioning system based on the Lagrangian points themselves. These first two methods depend crucially on the synchronization of clocks at L₁ and L₂. The third method combines a pulsar and an artificial emitter at the stable points L₄ or L₅ forming a basis for the positioning of the collinear points L₁ and L₂. Further possibilities are mentioned and the feasibility of the measurements is considered.

Assuming the universe as a thermodynamical system, the second law of thermodynamics can be extended to another form including the sum of matter and horizon entropies, which is called the generalized second law of thermodynamics. The generalized form of the second law (GSL) is universal which means it holds both in non-equilibrium and equilibrium pictures of thermodynamics. Considering the universe is bounded by a dynamical apparent horizon, we investigate the nature of entropy function for the validity of GSL in the scalar–tensor–vector (STEVE) theory of gravity.

In holography, there is a one-to-one correspondence between physical observables in the bulk and boundary theories. To define physical observables, however, regularization needs to be implemented in both sides of the correspondence. It is arguable whether the correspondence should extend to regularization and renormalization scheme which are not physical in the conventional sense. However, if we are to take the renormalization group (RG) interpretation of holography seriously, its precise understanding appears to require the matching of regularizations and renormalization schemes in the bulk and boundary theories. We address this question in the AdS₅/CFT₄ correspondence by considering the simplest physical quantity, the Casimir energy of the ${𝒩}=4$ super Yang–Mills (SYM) theory on $ℝ\times S^3$, in a $\zeta$-function regularization and show that there are choices of scheme which match the bulk AdS result, including the radial cutoff-dependent corrections when the cutoff is kept finite. We further discuss the implication of this result to the RG interpretation of holography.

This paper is devoted to examine the cracking of spherically symmetric anisotropic fluid configuration for polytropic equation of state. For this purpose, we formulate the corresponding field equations as well as generalized Tolman–Oppenheimer–Volkoff equation. We introduce density perturbations in matter variables and then construct the force distribution function. In order to examine the occurrence of cracking/overturning, we consider two models corresponding to two values of the polytropic index. It is found that the first model exhibits overturning for the considered values of polytropic constant while the second model neither exhibits cracking nor overturning for larger values of polytropic constant.

The Casimir effect is one of the observable consequences of the vacuum fluctuations. The Casimir effect manifests itself as a force between two uncharged conductive plates in a vacuum placed a few nanometers apart. In this work, we try to deduce the Casimir effect directly from the uncertainty principle.

We show that a simple modification of the Lagrangian proposed by Padmanabhan in the paper [Mod. Phys. Lett. A 33, 1830005 (2018)] leads to the most general dynamical invariant in [Ray and Reid, Phys. Lett. A 71, 317 (1979)].