Probing Fuzzballs with Particles, Waves and Strings

TL;DR

This paper investigates how particles, waves, and strings interact with D1D5 fuzzball geometries, providing evidence supporting the fuzzball proposal by analyzing motion, scattering, and phase shifts in these complex gravitational backgrounds.

Contribution

It introduces a comprehensive analysis of probe interactions with fuzzball geometries using multiple methods, highlighting the dynamical consistency of the fuzzball proposal.

Findings

Deflection angles and phase shifts can be computed despite reduced symmetry.

Critical impact parameters determine when probes are captured by fuzzballs.

Results from different approaches agree, supporting the fuzzball model.

Abstract

We probe D1D5 micro-state geometries with massless particles, waves and strings. To this end, we study geodetic motion, Klein-Gordon equation and string scattering in the resulting gravitational background. Due to the reduced rotational symmetry, even in the simple case of a circular fuzzball, the system cannot be integrated elementarily. Yet, for motion in the plane of the string profile or in the orthogonal plane to it, one can compute the deflection angle or the phase shift and identify the critical impact parameter, at which even a massless probe is captured by the fuzzball if its internal momentum is properly tuned. We find agreement among the three approaches, thus giving further support to the fuzzball proposal at the dynamical level.