Emission spectrum of fundamental strings: an algebraic approach Original Research Article

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 MmR(1−D)/2, where mR 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.