Physical renormalization condition for de Sitter QED

Abstract

We considered a new renormalization condition for the vacuum expectation values of the scalar and spinor currents induced by a homogeneous and constant electric field background in de Sitter spacetime. Following a semiclassical argument, the condition named maximal subtraction imposes the exponential suppression on the massive charged particle limit of the renormalized currents. The maximal subtraction changes the behaviors of the induced currents previously obtained by the conventional minimal subtraction scheme. The maximal subtraction is favored for a couple of physically decent predictions including the identical asymptotic behavior of the scalar and spinor currents, the removal of the infrared (IR) hyperconductivity from the scalar current, and the finite current for the massless fermion.

Imprints of Schwinger effect on primordial spectra

“…In short, we focus on the signatures produced. Schwinger effect is studied in 2D [32][33][34] and 4D [35][36][37][38][39] de Sitter space. Unlike the flat space case, strong electric field is not needed in inflation to produce super light particles.…”

Induced energy-momentum tensor of a Dirac field in 2D de Sitter QED

“…Obviously, the infrared hyperconductivity and the negative current phenomena are contrary to physical intuition. In attempting to address these peculiarities, a new renormalization condition defined for the scalar and Dirac induced currents in dS 4 which was named maximal subtraction [94]. The maximal subtraction scheme defines the asymptotic value of the renormalized vacuum expectation value equal to that of obtained from the semiclassical approaches.…”

Kinetic approach to the Schwinger effect during inflation

“…Even the new generation of laser systems such as the Extreme Light Infrastructure [35,36] and the Exawatt Center for Extreme Light Studies [37] could produce the peak field strengths of only ∼ 10 −2 E cr which would still provide a very small production rate. The Schwinger effect may occur in other physical systems such as relativistic heavy-ion collisions [38][39][40][41][42], decays of "hadronic strings" during the process of hadronization [43], condensed matter physics [44], and, finally, in the early Universe [45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63] which is of the prime interest for our investigation.…”

“…[59], this case is unphysical since maintaining a constant electric field in an exponentially expanding universe would require the existence of ad hoc currents that could violate the second law of thermodynamics. Various cases of (1+1)-dimensional [46,48,49], (2+1)-dimensional [47], and (3+1)-dimensional [45,50,51,55,56] de Sitter spacetime with scalar [45-47, 51, 55-57] and spinor charged fields [48-50, 55, 56], including also an external magnetic field [54], were investigated. Unfortunately, the current of created particles obtained by direct averaging of the corresponding current operator contains ultraviolet divergences, which can be regularized using the adiabatic subtraction [45,50] or point-splitting method [51].…”