QUANTUM STRING PROPAGATION THROUGH GRAVITATIONAL SHOCK-WAVES

We study the propagation of quantum closed strings in gravitational shock wave space-times. We find the exact expressions of the expectation values of the total number operator 〈N〉 and of the mass square operator 〈M2〉 and analyze their properties. We show that they are both finite and that strings propagate consistently through gravitational shock waves. Exact integral representations for 〈N〉 and 〈M2〉 are found in which the presence of the real mass resonances characteristic of tree string amplitudes is exhibited. The issue of space-time singularities is briefly discussed. © 1990.