Revisit to non-decoupling MSSM

Abstract

Dipole operator s¯σμνFμνb requires the helicity flip in the involving quark states thus the breaking of chiral U(3)Q×U(3)d. On the other hand, the b quark mass generation is also a consequence of chiral U(3)Q×U(3)d symmetry breaking. Therefore, in many models, there might be strong correlation between the b→sγ and b quark Yukawa coupling. In this Letter, we use non-decoupling MSSM model to illustrate this feature. In the scenario, the light Higgs boson may evade the direct search experiments at LEPII or Tevatron while the 125 GeV Higgs-like boson is identified as the heavy Higgs boson in the spectrum. A light charged Higgs is close to the heavy Higgs boson which is of 125 GeV and its contribution to b→sγ requires large supersymmetric correction with large PQ and R-symmetry breaking. The large supersymmetric contribution at the same time significantly modifies the b quark Yukawa coupling. With combined flavor constraints B→Xsγ and Bs→μ+μ− and direct constraints on Higgs properties, we find best fit scenarios with light stop of O(500 GeV), negative At around −750 GeV and large μ-term of 2–3 TeV. In addition, reduction in bb¯ partial width may also result in large enhancement of ττ decay branching fraction. Large parameter region in the survival space under all bounds may be further constrained by H→ττ if no excess of ττ is confirmed at LHC. We only identify a small parameter region with significant H→hh decay that is consistent with all bounds and reduced ττ decay branching fraction. In the end, if current dark matter mostly consists of neutralino, direct detection experiments like XENON100 also puts stringent bound over this scenario with light Higgs bosons. The light stops which are required by flavor constraints can further enhance the scattering cross section.