Challenging SO(10) SUSY GUTs with family symmetries through FCNC processes

TL;DR

This paper critically examines the SO(10) SUSY GUT model with D3 family symmetry, revealing significant challenges in simultaneously fitting flavor-changing neutral current processes without resorting to unnatural scalar mass regions.

Contribution

It provides a comprehensive global fit of the model to FCNC observables, highlighting the tension between naturalness and the model's ability to match experimental data.

Findings

Model can fit quark and lepton masses and mixing matrices.

FCNC processes impose severe constraints on SUSY spectrum.

Naturalness is challenged by the scalar mass requirements for FCNC suppression.

Abstract

We perform a detailed analysis of the SO(10) SUSY GUT model with D3 family symmetry of Dermisek and Raby (DR). The model is specified in terms of 24 parameters and predicts, as a function of them, the whole MSSM set of parameters at low energy scales. Concerning the SM subset of such parameters, the model is able to give a satisfactory description of the quark and lepton masses, of the PMNS matrix and of the CKM matrix. We perform a global fit to the model, including flavour changing neutral current (FCNC) processes Bs --> mu+ mu-, B --> Xs gamma, B --> Xs l+ l- and the B(d,s) - bar B(d,s) mass differences Delta M(d,s) as well as the flavour changing (FC) process B+ --> tau+ nu. These observables provide at present the most sensitive probe of the SUSY mass spectrum and couplings predicted by the model. Our analysis demonstrates that the simultaneous description of the FC observables in question represents a serious challenge for the DR model, unless the masses of the scalars are moved to regions which are problematic from the point of view of naturalness and probably beyond the reach of the LHC. We emphasize that this problem could be a general feature of SUSY GUT models with third generation Yukawa unification and weak-scale minimal flavour violation.