# Stringy Black Hole Interiors

## TL;DR

This paper proposes a new non-perturbative string theory operator to describe black hole interiors, replacing problematic analytic continuations with a model of folded strings that fill the black hole and radiate at Hawking temperature.

## Contribution

It introduces a novel operator for non-perturbative corrections in Lorentzian black holes, providing a consistent description of the interior filled with folded strings.

## Key findings

- The new operator avoids issues of analytic continuation.
- Folded strings fill the black hole interior.
- Radiation from these strings matches Hawking temperature.

## Abstract

It is well known that non-perturbative $\alpha'$ corrections to the $SL(2,\IR)/U(1)$ cigar geometry are described via a condensation of a Sine-Liouville operator that schematically can be written as $W^{+}+W^{-}$, where $W^{\pm}$ describe a string with winding number $\pm 1$. This condensation leads to interesting effects in the cigar geometry that take place already at the classical level in string theory. Condensation of the analytically continued Sine-Liouville operator in the Lorentzian $SL(2,\IR)/U(1)$ black hole is problematic. Here, we propose that in the black hole case, the non-perturbative $\alpha'$ corrections are described in terms of an operator that can be viewed as the analytic continuation of the fusion of $W^+$ and $W^-$. We show that this operator does not suffer from the same problem as the analytically continued Sine-Liouville operator and argue that it describes folded strings that fill the entire black hole and, in a sense, replace the black hole interior. We estimate the folded strings radiation, and show that they radiate at the Hawking temperature.