Screening Stringy Horizons

TL;DR

This paper investigates how string theory effects modify the black hole geometry, focusing on worldsheet instantons' influence on scattering phase-shifts in two-dimensional models, highlighting the dual description's relevance at high energies.

Contribution

It analyzes the role of worldsheet instantons in 2D black hole sigma-models and their impact on scattering phase-shifts, emphasizing the significance of the dual model at high energies.

Findings

Instantons significantly affect the scattering phase-shift.

High-energy physics is better described by the dual model.

Stringy effects modify the effective black hole geometry.

Abstract

It has been argued recently that string theory effects qualitatively modify the effective black hole geometry experienced by modes with radial momentum of order $1/\sqrt{\alpha'}$. At tree level, these $\alpha'$-effects can be explicitly worked out in two-dimensional string theory, and have a natural explanation in the T-dual description as coming from the integration of the zero-mode of the linear dilaton, what yields a contribution that affects the scattering phase-shift in a peculiar manner. It has also been argued that the phase-shift modification has its origin in a region of the moduli space that does not belong to the exterior black hole geometry, leading to the conclusion that at high energy the physics of the problem is better described by the dual model. Here, we elaborate on this argument. We consider the contribution of worldsheet instantons in the 2D Euclidean black hole sigma-model and study its influence on the phase-shift at high energy.