We present simple new approximate formulas, for both scalar and spinor QED, for the
number of particles produced from vacuum by a time-dependent electric field, incorporating …

We consider quantum field theoretic systems subject to a time-dependent perturbation, and
discuss the question of defining a time-dependent particle number not just at asymptotic …

We consider the time evolution of the adiabatic particle number in both time-dependent
electric fields and in de Sitter spaces, and define a superadiabatic particle number in which …

We investigate particle production à la the Schwinger mechanism in an expanding, flat de
Sitter patch as is relevant for the inflationary epoch of our Universe. Defining states and …

Over the years, de Sitter spacetime has been a central focus in studies involving quantum
fields, for its importance in the early and late expansion stages of the universe. While de …

Since the work of Sauter, and Heisenberg, Euler and Köckel, it has been understood that
vacuum polarization effects in quantum electrodynamics (QED) predict remarkable new …

In the present work we study the process of particle creation for mass dimension one
fermionic fields (sometimes named Elko) as a consequence of expansion of the universe …

Our knowledge about the universe has increased tremendously in the last three decades or
so—thanks to the progress in observations—but our understanding has improved very little …

We discuss several aspects of particle production in (a) a time-dependent electric field and
(b) an expanding Friedmann background. In the first part of the paper, we provide an …

We study the evolution of a quantum scalar field in a toy universe which has three stages of
evolution, viz.,(i) an early (inflationary) de Sitter phase (ii) radiation-dominated phase and …