Computational study of baryon number violation in high energy electroweak collisions

We use semiclassical methods to study processes which give rise to change of topology and therefore to baryon number violation in the standard model. We consider classically allowed processes, i.e., energies above the sphaleron barrier. We develop a computational procedure that allows us to solve the Yang-Mills equations of motion for spherically symmetric configurations and to identify the particle numbers of the in and out states. A stochastic sampling technique is then used to map the region spanned by the topology changing solutions in the energy versus incoming particle number plane and, in particular, to determine its lower boundary. A lower boundary which approaches small particle number would be a strong indication that baryon number violation would occur in high energy collisions, whereas a lower asymptote at large particle number would be evidence of the contrary. With our method and the computational resources we have had at our disposal, we have been able to determine the lower boundary up to energies approximately equal to one and a half times the sphaleron energy and observed a 40% decrease in particle number with no sign of the particle number leveling off. However encouraging this may be, the decrease in incoming particle number is only from 50 particles down to approximately 30. Nevertheless, the formalism we have established will make it possible to extend the scope of this investigation and also to study processes in the classically forbidden region, which we plan to do in the future. copyright 1996 The American Physical Society