The Charged Black Hole/String Transition

TL;DR

This paper explores the transition from charged black holes to string phases, identifying a temperature-driven phase change characterized by a massless tachyon and horizon smearing, with implications for higher-dimensional black holes.

Contribution

It extends the analysis of black hole/string transitions to charged black holes, proposing a similar transition mechanism and examining the role of tachyon condensation in this process.

Findings

Transition occurs at the Hawking temperature matching string temperature.

Tachyon winding becomes massless at the transition point.

Proposed similar properties for higher-dimensional Reissner-Nordstrom black holes.

Abstract

We generalize the discussion of hep-th/0509170 to charged black holes. For the two dimensional charged black hole, which is described by an exactly solvable worldsheet theory, a transition from the black hole to the string phase occurs when the Hawking temperature of the black hole reaches a limiting value, the temperature of free strings with the same mass and charge. At this point a tachyon winding around Euclidean time in the Euclidean black hole geometry, which has a non-zero condensate, becomes massless at infinity, and the horizon of the black hole is infinitely smeared. For Reissner-Nordstrom black holes in d\ge 4 dimensions, the exact worldsheet CFT is not known, but we propose that it has similar properties. We check that the leading order solution is in good agreement with this proposal, and discuss the expected form of \alpha' corrections.