We show that in the isentropic scenario the first order thermodynamical particle creation model gives an emergent universe solution even when the chemical potential is non-zero. However there exists no emergent universe scenario in the second order non-equilibrium theory for the particle creation model. We then point out a correspondence between the particle creation model with barotropic equation of state and the equation of state giving rise to an emergent universe without particle creation in spatially flat FRW cosmology.

In this paper we consider the flat FRW cosmology with a scalar field coupled with the metric along with generalized Chaplygin gas and perfect fluid comprising the matter sector. We use the Schutz's formalism to deal with the generalized Chaplygin gas sector. The full theory is then quantized canonically using the Wheeler-DeWitt Hamiltonian formalism. We then solve the WD equation with appropriate boundary conditions. Then by defining a proper completeness relation for the self-adjointness of the WD equation we arrive at the wave packet for the universe. It is observed that the peak in the probability density gets affected due to both fluids in the matter sector, namely, the Chaplygin gas and perfect fluid.

In this article we employ the matching method to analytically investigate the properties of holographic superconductors in the framework of Maxwell electrodynamics taking into account the effects of back reaction on spacetime. The relationship between the critical temperature (T c ) and the charge density (ρ) has been obtained first. The influence of back reaction on Meissner like effect in this holographic superconductor is then studied. The results for the critical temperature indicate that the condensation gets harder to form when we include the effect of back reaction. The expression for the critical magnetic field (B c ) above which the superconducting phase vanishes is next obtained. It is observed from our investigation that the ratio of B c and T 2 c increases with the increase in the back reaction parameter. However, the critical magnetic field B c decreases with increase in the back reaction parameter. *

In this paper, we study a noncommutative quantum description of Kantowski–Sachs cosmological model in the presence of perfect fluid matter field which governs the time evolution of the wave function for the universe. The effect of the noncommutative parameter for this cosmological model has also been analyzed through the behavior of the probability density function. It is observed that a multiverse universe model is possible even in the absence of noncommutativity. The effect of noncommutativity is revealed by a decrease in the highest value of the individual peaks. We also discuss on the unitarity of the model and show that it can be restored with a proper definition of inner product as it has been shown to happen in other models of anisotropic quantum cosmologies.

The implications of considering interaction between Chaplygin gas and a barotropic fluid with constant equation of state have been explored. The unique feature of this work is that assuming an interaction Q ∝ Hρ d , analytic expressions for the energy density and pressure have been derived in terms of the Hypergeometric 2F1 function. It is worthwhile to mention that an interacting Chaplygin gas model was considered in 2006 by Zhang and Zhu, nevertheless, analytic solutions for the continuity equations could not be determined assuming an interaction proportional to H times the sum of the energy densities of Chaplygin gas and dust. Our model can successfully explain the transition from the early decelerating phase to the present phase of cosmic acceleration. Arbitrary choice of the free parameters of our model through trial and error show at recent observational data strongly favors wm = 0 and wm = − case. Interestingly, the present model also incorporates the transition of dark energy into the phantom domain, however, future deceleration is forbidden.