# Overlaps after quantum quenches in the sine-Gordon model

## TL;DR

This paper numerically computes overlaps after quantum quenches in the sine-Gordon model using TCSA, introducing a new running coupling to enhance accuracy, and confirms an analytical Ansatz for the initial state.

## Contribution

It develops a novel running coupling method in TCSA for sine-Gordon model and validates an analytical initial state Ansatz for quantum quenches.

## Key findings

- Numerical overlaps agree with the analytical Ansatz.
- The new running coupling reduces cut-off dependence in TCSA.
- Method applicable to other free boson quantum field theories.

## Abstract

We present a numerical computation of overlaps in mass quenches in sine-Gordon quantum field theory using truncated conformal space approach (TCSA). To improve the cut-off dependence of the method, we use a novel running coupling definition which has a general applicability in free boson TCSA. The numerical results are used to confirm the validity of a previously proposed analytical Ansatz for the initial state in the sinh-Gordon quench.