String-theoretic unitary S-matrix at the threshold of black-hole production

TL;DR

This paper reformulates trans-Planckian collision results in superstring theory into an explicitly unitary S-matrix, revealing black-hole-like features at energies below the threshold, suggesting a smooth transition to black-hole physics.

Contribution

It introduces a new unitary S-matrix framework for high-energy string collisions, highlighting black-hole-like phenomena below the production threshold.

Findings

Final state properties resemble black-hole evaporation near threshold.

Inclusive cross sections exhibit anti-scaling behavior.

Results suggest a transition to black-hole physics at sub-threshold energies.

Abstract

Previous results on trans-Planckian collisions in superstring theory are rewritten in terms of an explicitly unitary S-matrix whose range of validity covers a large region of the energy/impact-parameter plane. Amusingly, as part of this region's border is approached, properties of the final state start resembling those expected from the evaporation of a black-hole even well below its production threshold. More specifically, we conjecture that, in an energy window extending up such a threshold, inclusive cross sections satisfy a peculiar "anti-scaling" behaviour seemingly preparing for a smooth transition to black-hole physics.