High-energy multileg electroweak processes and unitarity
(EN)
Cornwall, JM
(EN)
Tiktopoulos, G
(EN)
Because of the failure of the dilute-instanton-gas approximation (DIGA) at high energies, recent calculations of (B + L)-violating processes in the standard model show blatant violations of unitarity, and suggest that these processes may be relatively unsuppressed at multiplicities N approximately alpha(W)-1. We show how to cure the DIGA failure and restore the high-energy behavior necessary for consistency with unitarity in two ways: one in Minkowski space and the other in Euclidean space. In Euclidean space this is done by solving the classical field equations in the presence of space-time-dependent sources; we work out an explicit example. The same techniques allow us to investigate a similar failure of.high-energy behavior in perturbation theory [(B + L)-conserving processes] as studied with the DIGA in the manner of Lipatov. An independent Minkowski-space analysis, also dealing with classical solutions in the presence of sources, confirms these results and shows that even with the right high-energy behavior, factors growing rapidly with N when N greater-than-or-equal-to alpha(W)-1 still violate unitarity in the (B + L)-conserving sector. Within the framework of a simple model which automatically restores unitarity, we investigate whether dispersion integrals relating high- and low-energy (B + L)-violating processes can restrict the size of the high-energy B + L violation, and find that they cannot.
(EN)
