Vacuum States in 2D Tachyon Effective Action

TL;DR

This paper investigates the classical and quantum vacuum states of a 2D tachyon effective action model, demonstrating the existence of a family of vacua with no backreaction on the metric and dilaton fields.

Contribution

It constructs classical solutions and analyzes quantum vacuum states of the 2D tachyon effective action, including zero and nonzero modes, showing no backreaction occurs.

Findings

Identified a family of vacuum states parametrized by a single parameter.

Quantum analysis shows no backreaction on metric and dilaton.

Calculated stress-energy tensor and dilaton source expectation values.

Abstract

In this paper we will study the ground states of the toy model of 2D closed string tachyon effective action. We will firstly construct the classical solutions of the tachyon effective action that do not induce backreaction on metric and dilaton. Then we will study the quantum mechanics of the zero mode of the tachyon field. We will find family of vacuum states labelled with single parameter. We will also perform the quantum mechanical analysis of the tachyon effective action when we take into account dynamics of nonzero modes. We will calculate the vacuum expectation values of components of the stress energy tensor and dilaton source and we will argue that there is not any backreaction on metric and dilaton.