Fixing EFT equations with a reservoir model

TL;DR

This paper introduces a reservoir model coupling to higher-derivative effective field theories, transforming ill-posed equations into well-posed problems by dissipating short-wavelength energy into an extra dimension.

Contribution

It proposes a novel method of coupling EFTs to an extra-dimensional reservoir to improve control and well-posedness of their equations of motion.

Findings

The method stabilizes the equations of motion.

It effectively dissipates UV energy into the extra dimension.

Comparison shows advantages over existing approaches.

Abstract

Effective Field Theories with higher derivatives often yield equations of motion which define ill-posed problems. We present a method for enhancing control on such theories by coupling them to a field living in one extra dimension. The resulting action principle helps to define a well-posed problem introducing a mechanism to control UV behavior. Physically this is achieved by dissipating the energy in the short-wavelength modes into the extra dimension. We examine the resulting dynamics and compare it to alternative proposals for studying such theories in the non-linear regime.