Baryon number nonconservation and phase transitions at preheating - art. no. 103510

Certain inflation models undergo pre-heating, in which inflaton oscillation s can drive parametric resonance instabilities. We discuss several phenomen a stemming from such instabilities, especially in weak-scale models; generi cally, these involve energizing a resonant system so that it can evade tunn eling by crossing barriers classically. One possibility is a spontaneous ch ange of phase from a lower-energy vacuum state to one of higher energy, as exemplified by an asymmetric double-well potential with different masses in each well. If the lower well is in resonance with oscillations of the pote ntial, a system can be driven resonantly to the upper well and stay there ( except for tunneling) if the upper well is not resonant. Another example oc curs in hybrid inflation models where the Higgs field is resonant; the Higg s oscillations can be transferred to electroweak (EW) gauge potentials, lea ding to rapid transitions over sphaleron barriers and consequent B + L viol ation. Given an appropriate CP-violating seed, we find that preheating can drive a time-varying condensate of Chern-Simons number over large spatial s cales; this condensate evolves by oscillation as well as decay into modes w ith shorter spatial gradients, eventually ending up as a condensate of spha lerons. We study these examples numerically and to some extent analytically . The emphasis in the present paper is on the generic mechanisms, and not o n specific preheating models; these will be discussed in a later paper.