Supersymmetric Electroweak Baryogenesis Via Resonant Sfermion Sources

TL;DR

This paper investigates how resonant sfermion sources in supersymmetric models can generate the observed baryon asymmetry during the electroweak phase transition, considering experimental constraints and proposing new viable sources like quasi-degenerate staus.

Contribution

It provides a detailed calculation of baryon asymmetry from sfermion sources, analyzes experimental constraints, and introduces a new class of CP-violating sources that can successfully produce baryogenesis.

Findings

Resonant sfermion sources can generate sufficient baryon asymmetry in certain parameter regions.

Stop and sbottom sources are ruled out by Mercury EDM constraints.

Quasi-degenerate staus can produce baryon asymmetry while evading current EDM bounds.

Abstract

We calculate the baryon asymmetry produced at the electroweak phase transition by quasi-degenerate third generation sfermions in the minimal supersymmetric extension of the Standard Model. We evaluate constraints from Higgs searches, from collider searches for supersymmetric particles, and from null searches for the permanent electric dipole moment (EDM) of the electron, of the neutron and of atoms. We find that resonant sfermion sources can in principle provide a large enough baryon asymmetry in various corners of the sfermion parameter space, and we focus, in particular, on the case of large $\tan\beta$, where third-generation down-type (s)fermions become relevant. We show that in the case of stop and sbottom sources, the viable parameter space is ruled out by constraints from the non-observation of the Mercury EDM. We introduce a new class of CP violating sources, quasi-degenerate staus, that escapes current EDM constraints while providing large enough net chiral currents to achieve successful "slepton-mediated" electroweak baryogenesis.