Classical Stringy Black Holes Modify the Thermal Spectrum

Non-local (alpha prime) corrections to Schwarzschild black holes are shown to invalidate the thermodynamical interpretation of black holes. In particular, the canonical and Bekenstein-Hawking temperatures are not equal. The particle number density of fields quantized in the (alpha prime modified) black hole background is no longer thermal. In the non-perturbative region (alpha prime going to infinity or mass going to zero), an analytic continuation to the number density is shown to vanish exponentially.