Decays of massive open strings

Abstract

The asymptotic total decay rates for arbitrarily massive states on the leading Regge trajectory for open bosonic strings and SO(32) superstrings are calculated. In the bosonic case, the result corresponds to a local splitting probability per unit length only in d = 26: for fewer than 24 transverse directions the rate is smaller. This provides a new interpretation of the critical dimension. For superstrings there is a splitting probability per unit length, independent of compactification. Compactifying rather than truncating the bosonic string leads to a similar result.