Flavor Physics in an SO(10) Grand Unified Model

TL;DR

This paper analyzes a supersymmetric SO(10) GUT model where lepton mixing influences quark flavor transitions, finding it can accommodate large B_s mixing effects and predicts a distinctive superpartner spectrum.

Contribution

It provides a detailed correlation between low-energy flavor observables and the parameters of a specific SO(10) GUT model, highlighting its unique predictions compared to CMSSM.

Findings

Current bounds on tau -> mu gamma constrain sfermion masses above 1 TeV.

The model allows large CP phases in B_s-B_s-bar mixing consistent with data.

Predicted superpartner spectrum differs from CMSSM, with lighter stops possible.

Abstract

In supersymmetric grand-unified models, the lepton mixing matrix can possibly affect flavor-changing transitions in the quark sector. We present a detailed analysis of a model proposed by Chang, Masiero and Murayama, in which the near-maximal atmospheric neutrino mixing angle governs large new b -> s transitions. Relating the supersymmetric low-energy parameters to seven new parameters of this SO(10) GUT model, we perform a correlated study of several flavor-changing neutral current (FCNC) processes. We find the current bound on B(tau -> mu gamma) more constraining than B(B -> X_s gamma). The LEP limit on the lightest Higgs boson mass implies an important lower bound on tan beta, which in turn limits the size of the new FCNC transitions. Remarkably, the combined analysis does not rule out large effects in B_s-B_s-bar mixing and we can easily accomodate the large CP phase in the B_s-B_s-bar system which has recently been inferred from a global analysis of CDF and DO data. The model predicts a particle spectrum which is different from the popular Constrained Minimal Supersymmetric Standard Model (CMSSM). B(tau -> mu gamma) enforces heavy masses, typically above 1 TeV, for the sfermions of the degenerate first two generations. However, the ratio of the third-generation and first-generation sfermion masses is smaller than in the CMSSM and a (dominantly right-handed) stop with mass below 500 GeV is possible.