Brane Decay and Death of Open Strings

TL;DR

This paper investigates how open strings stop propagating during D-brane decay, analyzing two backgrounds: static tachyon kinks and homogeneous rolling tachyons, revealing different propagation behaviors.

Contribution

It provides a detailed analysis of open string propagation during D-brane decay using BSFT two-point functions in specific tachyon backgrounds, highlighting the collapse of open string excitations.

Findings

Propagation along tachyon kink directions persists in static backgrounds.

All open string excitations cease to propagate in the late-time rolling tachyon background.

Open string light cones collapse, indicating a Carrollian contraction of Lorentz symmetry.

Abstract

We show how open strings cease to propagate when unstable D-branes decay. The information on the propagation is encoded in BSFT two-point functions for arbitrary profiles of open string excitations. We evaluate them in tachyon condensation backgrounds corresponding to (i) static spatial tachyon kink (= lower dimensional BPS D-brane) and (ii) homogeneous rolling tachyon. For (i) the propagation is restricted to the directions along the tachyon kink, while for (ii) all the open string excitations cease to propagate at late time and are subject to a collapsed light cone characterized by Carrollian contraction of Lorentz group.