Gauge Fields and Scalars in Rolling Tachyon Backgrounds

TL;DR

This paper studies the behavior of gauge and scalar fields on unstable D-branes with rolling tachyons, revealing how their dynamics are affected by an effective metric and curvature effects in a cosmological setting.

Contribution

It derives the equations of motion for gauge and scalar fields in a rolling tachyon background with an arbitrary potential and scale factor, highlighting the effective metric and curvature corrections.

Findings

Fields experience an effective metric different from the FRW metric.

Large corrections to field equations due to curvature and time-varying gauge coupling.

Equations of state resemble nonrelativistic matter.

Abstract

We investigate the dynamics of gauge and scalar fields on unstable D-branes with rolling tachyons. Assuming an FRW metric on the brane, we find a solution of the tachyon equation of motion which is valid for arbitrary tachyon potentials and scale factors. The equations of motion for a U(1) gauge field and a scalar field in this background are derived. These fields see an effective metric which differs from the original FRW metric. The field equations receive large corrections due to the curvature of the effective metric as well as the time variation of the gauge coupling. The equations of state for these fields resemble those of nonrelativistic matter rather than those of massless particles.