Massless radiation from heavy rotating string and Kerr/string correspondence Original Research Article

We calculate emission rates of a massless state from a highly excited rotating string in perturbative bosonic open string theory. By averaging huge degeneracies of initial string states with specifying the mass and a single component of the angular momentum, we find thermal spectrum in a wide range of the angular momentum. We derive the temperature that characterizes the thermal spectrum from the partition function of a single rotating string from which we also find the entropy and the angular velocity of rotating strings. We also argue based on these quantities the Horowitz–Polchinski correspondence principle between rotating strings/Kerr black holes for non-extremal as well as extremal cases. In the parameter region where the Kerr black holes exist, the thermal spectrum is comparable to scalar emissions from a rotating black hole.