A bulk model for dissipation and fixing EFT equations on its boundary

Abstract

Effective field theories (EFTs) with higher derivatives often yield equations of motion that define ill-posed problems. We present an action-based approach that supplements a recent well-posed formulation of Figueras et al. with selective dissipation: the EFT field is coupled to an auxiliary field living in one extra dimension, into which the energy of short-wavelength modes can dissipate. The construction is tested numerically on a scalar EFT with a known ultraviolet completion. We observe a reduction in spurious oscillations, and, for large couplings, in error. We also compare with the fixing-the-equations approach, and outline the extension to gravity.

22 pages, 3 figures