Emission spectrum of fundamental strings: an algebraic approach

Abstract

We formulate a linear difference equation which yields averaged semi-inclusive decay rates for arbitrary, not necessarily large, values of the masses. We show that the rates for decays M→ m+ M′ of typical heavy open strings are independent of the masses M and m, and compute the “mass defect” M– m– M′. For closed strings we find decay rates proportional to Mm R (1− D)/2 , where m R is the reduced mass of the decay products. Our method yields exact interaction rates valid for all mass ranges and may provide a fully microscopic basis, not limited to the long string approximation, for the interactions in the Boltzmann equation approach to hot string gases.