Non-Thermal Behavior in Conformal Boundary States

TL;DR

This paper explains the non-thermal, periodic behavior of certain conformal boundary states in 1+1 CFTs, showing they are conformal transformations of ground states and discussing implications for thermalization and holography.

Contribution

It demonstrates that specific boundary states are Lorentz conformal transformations of ground states, revealing their non-thermal nature and extending understanding of thermalization in CFTs.

Findings

States are Lorentz conformal transformations of ground states.

Such states exhibit periodic, non-thermal behavior.

Implications for holographic dual descriptions.

Abstract

Cardy has recently observed that certain carefully tuned states of 1+1 CFTs on a timelike strip are periodic with period set by the light-crossing time. The states in question are defined by Euclidean time evolution of conformal boundary states associated with the particular boundary conditions imposed on the edges of the strip. We explain this behavior, and the associated lack of thermalization, by showing that such states are Lorentz-signature conformal transformations of the strip ground state. Taking the long-strip limit implies that states used to model thermalization on the Minkowski plane admit non-thermal conformal extensions beyond future infinity of the Minkowski plane, and thus retain some notion of non-thermal behavior at late times. We also comment on the holographic description of these states.