Bounds on flavour violating parameters in supersymmetry

TL;DR

This paper derives model-independent bounds on flavour violating parameters in supersymmetry using B --> X_s gamma decay data, analyzing various SUSY contributions and their interference effects.

Contribution

It provides a systematic leading logarithmic QCD analysis of flavour violation constraints in the MSSM, identifying key bounds on down squark mass matrix elements.

Findings

Two combinations of down squark mass matrix elements are tightly constrained.

SUSY contributions can significantly enhance the Wilson coefficient C_8(m_W).

Constraints are robust over large parameter space regions.

Abstract

We investigate the constraints on the flavour violating parameters from the decay B --> X_s gamma, taking into account the interplay of the various sources of flavour violation in the unconstrained MSSM. We present a systematic leading logarithmic QCD analysis of these model-independent constraints, including contributions from gluinos, neutralinos, charginos, charged Higgs bosons and interferences between them. We show that two simple combinations of elements of the down squark mass matrix are stringently bounded over large parts of the parameter space where only weak assumptions on the hierarchical structure of the squark mass matrices are made. We also briefly analyse up to which values SUSY contributions, compatible with B --> X_s gamma, can enhance the Wilson coefficient C_8(m_W), which plays an important role in the phenomenology of charmless hadronic B decays.