Closed String Emission from Unstable D-brane with Background Electric Field

TL;DR

This paper investigates how a constant background electric field affects the emission of closed strings from an unstable D-brane, showing that the electric field makes the energy density finite and negligible compared to the brane tension.

Contribution

It provides explicit calculations of closed string emission and demonstrates the regularizing effect of the electric field on energy density in bosonic string theory.

Findings

Energy density in UV region becomes finite with electric field

Energy converted into closed strings is negligible compared to D-brane tension

Electric field regularizes the emission process

Abstract

We study the closed string emission from an unstable D$p$-brane with constant background electric field in bosonic string theory. The average total number density and the average total energy density of emitted closed strings are explicitly calculated in the presence of electric field. It is explicitly shown that the energy density in the UV region becomes finite whenever the background electric field is switched on. The energy density converted into closed strings in the presence of electric field is negligibly small compared with the D-brane tension in the weak string coupling limit.