I outline some nonperturbative relativistic effects that arise from gravitational corrections to the Boltzmann equations. These may be important for the study of CMB temperature anisotropies, particularly their interpretation. These terms are not included in the canonical treatment as they arise from the exact equations. Here a weakly nonlinear investigation of these effects is defined and inve...

The aim of the present paper is to examine the effect of a quasi-periodic gravitational modulation on the onset of convective instability in Hele-Shaw cell. The quasi-periodic modulation considered here consists in a modulation having two incommensurate frequencies. This study is an extension of a previous work by Aniss et al. [10] in which only a periodic gravitational modulation was considere...

A bstract Effects of massive object’s spin on massive-massless 2 → classical scattering is studied. Focus set the less-considered dimensionless expansion parameter λ/b , where λ massless particle’s wavelength and b impact parameter. Corrections in start to appear from $$ \mathcal{O} O ( G ), with leading corr...

Gravitational counterpart of the chiral magnetic effect, which is referred as gravitational can also be interest in a cosmological setup. In this study, we investigate effect time-dependent asymmetric fermion background and expanding spacetime by formulating effective action waves. We analyze anomaly equation to see how backreaction from waves thermal plasma occurs. find that non-trivial time d...

We estimate the possible variations of the gravitational constant G in the framework of a generalized (BergmannWagoner-Nordtvedt) scalar-tensor theory of gravity on the basis of the field equations, without using their special solutions. Specific estimates are essentially related to the values of other cosmological parameters (the Hubble and acceleration parameters, the dark matter density etc....

The Machian cosmological solution satisfying φ = O(ρ/ω) for the perfect-fluid with negative pressure is discussed. When the coefficient of the equation of state γ → −1/3, the gravitational constant approaches to constant. If we assume the present mass density ρ0 ∼ ρc (critical density), the parameter ǫ (γ = (ǫ− 1)/3) has a value of order 10−3 to support the present gravitational constant. The c...