On the coherent inelastic binary and multiparticle processes in ultrarelativistic hadron–nucleus, photon–nucleus and nucleus–nucleus collisions

Abstract

The coherent inelastic processes of the type a→b, which may take place in the interaction of hadrons and γ quanta with nuclei at very highenergies (the nucleusremainsthe same), are theoretically investigated. For taking into accounttheinfluenceof thenucleus matter, the optical model, based on the concept of refraction index, is used. Analytical formulas for the effective cross section σcoh(a→b) are obtained, taking into account that at ultrarelativistic energies the main contribution into σcoh(a→b) is provided by very small transferred momenta in the vicinity of the minimum longitudinal momentum transferred to the nucleus. It is shown that the cross section σcoh(a→b) may be expressed through the “forward” amplitudes of inelastic scattering fa+N→b+N(0) and elastic scattering fa+N→a+N(0), fb+N→b+N(0) on a separate nucleon, and it depends on the ratios La/R and Lb/R, where La, Lb are the respective mean free paths in the nucleus matter for the particles a,b and R is the nuclear radius. The above formalism may be generalized also for the case of coherent inelastic multiparticle processes on a nucleus of the type a→{b1,b2,b3…bi} and for the case of coherent processes at collisions of two ultrarelativistic nuclei.