Seesaw mechanism in the sneutrino sector and its consequences

TL;DR

This paper explores the theoretical implications of the seesaw mechanism in the sneutrino sector within the MSSM, highlighting new flavor-changing processes, their bounds, and the potential origins of neutrino mass textures, while noting the limited observability of oscillations.

Contribution

It provides a comprehensive analysis of the full three-generation seesaw-extended MSSM, introducing new flavor-changing and CP-violating sneutrino processes and deriving formulas for oscillations.

Findings

New flavor-changing processes are bounded by rare decay rates.

Sneutrino-antisneutrino mixing contributes to neutrino mass corrections.

Sneutrino oscillations are unlikely to be observable at future colliders.

Abstract

The seesaw-extended MSSM provides a framework in which the observed light neutrino masses and mixing angles can be generated in the context of a natural theory for the TeV-scale. Sneutrino-mixing phenomena provide valuable tools for connecting the physics of neutrinos and supersymmetry. We examine the theoretical structure of the seesaw-extended MSSM, retaining the full complexity of three generations of neutrinos and sneutrinos. In this general framework, new flavor-changing and CP-violating sneutrino processes are allowed, and are parameterized in terms of two $3\times 3$ matrices that respectively preserve and violate lepton number. The elements of these matrices can be bounded by analyzing the rate for rare flavor-changing decays of charged leptons and the one-loop contribution to neutrino masses. In the former case, new contributions arise in the seesaw extended model which are not present in the ordinary MSSM. In the latter case, sneutrino--antisneutrino mixing generates the leading correction at one-loop to neutrino masses, and could provide the origin of the observed texture of the light neutrino mass matrix. Finally, we derive general formulae for sneutrino--antisneutrino oscillations and sneutrino flavor-oscillations. Unfortunately, neither oscillation phenomena is likely to be observable at future colliders.