LHC and lepton flavour violation phenomenology of a left-right extension of the MSSM

TL;DR

This paper explores a supersymmetric left-right extension of the MSSM, analyzing lepton flavor violation and slepton mass splittings at low energies, with predictions that differ from standard seesaw models, offering potential experimental signatures.

Contribution

It introduces a detailed phenomenological analysis of a left-right supersymmetric model with minimal supergravity, including 2-loop RGEs and novel LFV predictions in both slepton sectors.

Findings

LFV and slepton mass splittings occur in both left and right sectors.

Ratios of LFV decay branching ratios depend on symmetry breaking scales.

Positron polarization asymmetry in $oldsymbol{ ext{μ}^+ o e^+ ext{γ}}$ varies between 0 and 1.

Abstract

We study the phenomenology of a supersymmetric left-right model, assuming minimal supergravity boundary conditions. Both left-right and (B-L) symmetries are broken at an energy scale close to, but significantly below the GUT scale. Neutrino data is explained via a seesaw mechanism. We calculate the RGEs for superpotential and soft parameters complete at 2-loop order. At low energies lepton flavour violation (LFV) and small, but potentially measurable mass splittings in the charged scalar lepton sector appear, due to the RGE running. Different from the supersymmetric 'pure seesaw' models, both, LFV and slepton mass splittings, occur not only in the left- but also in the right slepton sector. Especially, ratios of LFV slepton decays, such as Br(${\tilde\tau}_R \to \mu \chi^0_1$)/Br(${\tilde\tau}_L \to \mu \chi^0_1$) are sensitive to the ratio of (B-L) and left-right symmetry breaking scales. Also the model predicts a polarization asymmetry of the outgoing positrons in the decay $\mu^+ \to e^+ \gamma$, A ~ [0,1], which differs from the pure seesaw 'prediction' A=1$. Observation of any of these signals allows to distinguish this model from any of the three standard, pure (mSugra) seesaw setups.