arXiv subjects
Publications and source records attributed to S. Davidson.
We construct basis-independent expressions that measure the magnitude of $R$-parity breaking due to possible superpotential terms in the Minimal Supersymmetric extension of the Standard Model, in the absence of soft supersymmetry-breaking terms and spontaneous gauge symmetry breaking. We also discuss briefly their application to a consistent treatment of cosmological constraints on $R$-parity violation.
We consider the evolution of baryon number $B$ in the early universe under the influence of rapid sphaleron interactions and show that $B$ will remain nonzero at all times even in the case of $B-L = 0$. This result arises due to thermal Yukawa interactions that cause nonidentical dispersion relations (thermal masses) for different lepton families. We point out the relevance of our result to the Affleck-Dine type baryogenesis.
Non-perturbative electroweak effects, in thermal equilibrium in the early universe, have the potential to erase the baryon asymmetry of the universe, unless it is encoded in a B-L asymmetry, or in some "accidentally" conserved quantity. We first consider the possibility that the BAU may be regenerated from lepton flavour asymmetries even when initially $B-L = 0$. We show that provided some, but {\it not} all the lepton flavours are violated by $ΔL{\neq}0$ interactions in equilibrium, the BAU may be regenerated without lepton mass effects. We next examine the possibility of encoding the baryon asymmetry in a primordial asymmetry for the right-handed electron, which due to its weak Yukawa interaction only comes into chemical equilibrium as the sphalerons are falling out of equilibrium. This would also raise the possibility of preserving an initial baryon asymmetry when $B-L = 0$.
We propose a new mechanism for baryogenesis in supersymmetric extensions of the standard model, that does not depend on (super)GUT interactions. It occurs by the non-perturbative electroweak reprocessing of a lepton asymmetry. This lepton asymmetry is generated by the effects of lepton number violating induced operators, arising from "see-saw" (s)neutrino masses, which act on scalar condensate oscillations along flat directions of the supersymmetric standard model.
We evaluate the constraints that the COBE observations put on baryogenesis in inflationary cosmologies.We consider the supersymmetric version of the proposal of Fukugita and Yanagida, that the baryon asymmetry of the universe is created by nonperturbative electroweak reprocessing of a lepton asymmetry generated in the decay of heavy right-handed see-saw (s)neutrinos. We review our recent proposal of a mechanism for baryogenesis via sphaleron reprocessing of a lepton asymmetry generated by (s)neutrino mass effects on flat direction scalar condensate oscillations. Finally we analyze in detail the implementation of these mechanisms in the recently proposed ansatze for fermion mass matrices in supersymmetric, unified, theories.