MOMENTUM CREATION BY VORTICES IN SUPERFLUID HE-3 AS A MODEL OF PRIMORDIAL BARYOGENESIS

The Universe contains much more matter than antimatter, which is proba bly the result of processes in the early Universe in which baryon numb er was not conserved. These processes may have occurred during the ele ctroweak phase transition, when elementary particles first acquired ma ss(1-4). It is impossible to study directly processes relevant to the early Universe, because of the extreme energies involved. One is there fore forced to investigate laboratory systems with analogous phase tra nsitions. Much of the behaviour of superfluid He-3 is analogous to tha t predicted within the standard model of the electroweak interaction(5 ). Superfluids and liquid crystals have already been used to investiga te cosmic-string production(6-11); here we describe experiments on He- 3 that demonstrate the creation of excitation momentum (which we call momentogenesis) by quantized vortices in the superfluid. The underlyin g physics of this process is similar to that associated with the creat ion of baryons within cosmic strings, and our results provide quantita tive support for this type of baryogenesis.