Energy Quantisation in Bulk Bouncing Tachyon

TL;DR

The paper proposes that closed string energy in a bulk bouncing tachyon background is quantized as if strings are confined in a finite time, supported by three different theoretical perspectives.

Contribution

It introduces a simple quantization scheme for closed string energy in the bulk bouncing tachyon background and explores its relation to S-branes and tachyon potential.

Findings

Quantization of energy resembles strings in a finite time interval.

Identification of a critical coupling  that signifies the bottom of the tachyon potential.

Parallel drawn between bulk bouncing tachyon and full S-brane decay.

Abstract

We argue that the closed string energy in the bulk bouncing tachyon background is to be quantised in a simple manner as if strings were trapped in a finite time interval. We discuss it from three different viewpoints; (1) the timelike continuation of the sinh-Gordon model, (2) the dual matrix model description of the (1+1)-dimensional string theory with the bulk bouncing tachyon condensate, (3) the c_L=1 limit of the timelike Liouville theory with the dual Liouville potential turned on. There appears to be a parallel between the bulk bouncing tachyon and the full S-brane of D-brane decay. We find the critical value \lambda_c of the bulk bouncing tachyon coupling which is analogous to \lambda_o=1/2 of the full S-brane coupling, at which the system is thought to be at the bottom of the tachyon potential.