Expectation values after an integrable boundary quantum quench

TL;DR

This paper develops a framework to analyze real-time dynamics after an integrable boundary quantum quench, using form factors and validated by numerical methods in the Lee-Yang model.

Contribution

It introduces a general approach for studying boundary quenches in integrable models, extending from conformal to massive regimes.

Findings

Analytical results for boundary quenches in the Lee-Yang model.

Validation of analytical predictions through numerical truncated conformal space approach.

Extension of methods from conformal to massive quantum field theories.

Abstract

We investigate an integrable boundary quench, in which one integrable boundary condition is suddenly switched to another. We develop a general framework for analyzing the resulting real-time dynamics based on form factors of bulk and boundary-changing operators. We first study the problem at the conformal point of the Lee-Yang model and then extend the analysis to its massive perturbation, where we examine the time evolution of the pre-quench vacuum and compute the vacuum-to-vacuum matrix elements of local operators inserted after the quench. The analytical results are validated by numerical calculations using the truncated conformal space approach adapted to boundary-changing situations.