Higher-spin localized shocks

TL;DR

This paper explores higher-spin fields in gravitational theories, revealing they admit localized shockwave solutions that relate to quantum chaos, with implications for the chaos bound and information spreading speeds.

Contribution

It demonstrates that higher-spin fields can produce localized shockwaves in black hole backgrounds, extending the understanding of chaos and shockwave solutions beyond spin-2 gravity.

Findings

Higher-spin shockwaves exist on black hole backgrounds.

Lyapunov exponent can violate the chaos bound.

Butterfly velocity may surpass the speed of light.

Abstract

In the context of AdS/CFT, gravitational shockwaves serve as a geometric manifestation of boundary quantum chaos. We study this connection in general diffeomorphism-invariant theories involving an arbitrary number of bosonic fields. Specifically, we demonstrate that theories containing spin-2 or higher-spin fields generally admit classical localized shockwave solutions on black hole backgrounds, whereas spin-0 and spin-1 theories do not. As in the gravitational case, these higher-spin shockwaves provide a means to compute the out-of-time-order correlator. Both the Lyapunov exponent and the butterfly velocity are found to universally agree with predictions from pole skipping. In particular, higher-spin fields lead to a Lyapunov exponent that violates the chaos bound and a butterfly velocity that may exceed the speed of light.