D-instantons in Real Time Dynamics

TL;DR

This paper investigates the role of D-instantons in real-time dynamics within holography, revealing how temperature influences instanton stability and their contributions to real-time fluctuations in a supergravity framework.

Contribution

It introduces a novel analysis of instanton effects in real-time holography by connecting Euclidean correlators to retarded correlators and examining temperature-dependent instanton stability.

Findings

Real-time topological charge fluctuations can destroy instantons.

Instanton lifetime decreases with increasing temperature.

Instanton contributions are suppressed at high temperature.

Abstract

Instanton is known to exist in Euclidean spacetime only. Their role in real time dynamics is usually understood as tunneling effect by Wick rotation. We illustrate other effects of instanton in holography by investigating 5d effective gravity theory of the black D3-brane-D-instanton system. The supergravity description of the D3-brane-D-instanton system is dual to the super Yang-Mills theory with topological excitations of the vacuum. We obtain Euclidean correlators in the presence of instantons by analyzing of the fluctuations of the bulk fields in the 5d effective theory. Furthermore, analytic continuation of Euclidean correlators leads to retarded correlators, which characterize real time dynamics. We find interestingly real time fluctuations of topological charge can destroy instantons and the lifetime of instanton is set by temperature. This implies instanton contribution to "real time dynamics" is suppressed at high temperature, which is analogous to classic field theory results that instanton contribution to "thermodynamics" is suppressed at high temperature.