Coupling of Rolling Tachyon to Closed Strings

TL;DR

This paper investigates the late-time dynamics of the rolling tachyon boundary state, revealing exponential growth in coupling to massive closed string modes and discussing energy dissipation and boundary state relations.

Contribution

It provides new insights into the late-time behavior of the rolling tachyon boundary state and its coupling to closed strings, highlighting the finite validity of the boundary state description.

Findings

Coupling to massive modes grows exponentially over time.

Boundary state description is valid only for finite times.

Energy can dissipate into the bulk beyond the validity period.

Abstract

We study the late time behavior of the boundary state representing the rolling tachyon constructed by Sen. It is found that the coupling of the rolling tachyon to massive modes of the closed string grows exponentially as the system evolves. We argue that the description of rolling tachyon by a boundary state is valid during the finite time determined by string coupling, and that energy could be dissipated to the bulk beyond this time. We also comment on the relation between the rolling tachyon boundary state and the spacelike D-brane boundary state.