Backdraft: String Creation in an Old Schwarzschild Black Hole

TL;DR

This paper investigates string production near Schwarzschild black holes, revealing that late-time observers experience significant nonadiabatic effects due to large boosts, which could relate to the firewall paradox.

Contribution

It develops first quantized methods to analyze string nonadiabatic effects in black hole backgrounds, extending understanding of string production during horizon crossing.

Findings

Late-time infalling observers experience strong boosts near the horizon.

Significant nonadiabatic string production occurs during horizon crossing for boosted probes.

Results generalize previous work on brane trajectories in black hole geometries.

Abstract

We analyze string production in the background of a Schwarzschild black hole, after developing first quantized methods which capture string-theoretic nonadiabatic effects which can exceed naive extrapolations of effective field theory. Late-time infalling observers are strongly boosted in the near horizon region relative to early observers and formation matter. In the presence of large boosts in flat spacetime, known string and D-brane scattering processes exhibit enhanced string production, even for large impact parameter. This suggests the possibility that the nonadiabatic dynamics required to realize the firewall proposal of AMPS occurs for old black holes, with the late-time observer catalyzing the effect. After setting up this dynamical thought experiment, we focus on a specific case: the production of open strings stretched D-particles, at least one of which falls in late (playing the role of a late time observer). For relatively boosted D-branes, we precisely recover earlier results of Bachas, McAllister and Mitra which we generalize to brane trajectories in the black hole geometry. For two classes of late-time probes, we find a regime of significant non-adiabaticity by horizon crossing, assessing its dependence on the boost in each case. Closed string probes, as well as additional effects in D-brane scattering, may produce other significant non-adiabatic effects depending on the boost, something we leave for further work.