Bounds on Regge growth of flat space scattering from bounds on chaos

TL;DR

This paper links chaos bounds in conformal field theories to the Regge growth of bulk S matrices in AdS/CFT, showing that chaos constraints limit the flat space S matrix growth to ensure consistency.

Contribution

It establishes a connection between chaos bounds in boundary CFTs and Regge growth constraints on bulk S matrices, deriving a new bound on flat space scattering amplitudes from holographic principles.

Findings

Regge scaling of correlators is constrained by chaos bounds.

Bulk S matrix growth must be no faster than s^2 in the Regge limit.

Chaos bounds imply the Classical Regge Growth conjecture for dual bulk theories.

Abstract

We study four-point functions of scalars, conserved currents, and stress tensors in a conformal field theory, generated by a local contact term in the bulk dual description, in two different causal configurations. The first of these is the standard Regge configuration in which the chaos bound applies. The second is the `causally scattering configuration' in which the correlator develops a bulk point singularity. We find an expression for the coefficient of the bulk point singularity in terms of the bulk S matrix of the bulk dual metric, gauge fields and scalars, and use it to determine the Regge scaling of the correlator on the causally scattering sheet in terms of the Regge growth of this S matrix. We then demonstrate that the Regge scaling on this sheet is governed by the same power as in the standard Regge configuration, and so is constrained by the chaos bound, which turns out to be violated unless the bulk flat space S matrix grows no faster than $s^2$ in the Regge limit. It follows that in the context of the AdS/CFT correspondence, the chaos bound applied to the boundary field theory implies that the S matrices of the dual bulk scalars, gauge fields, and gravitons obey the Classical Regge Growth (CRG) conjecture.