Exploring CP violation in the MSSM.

Abstract

We explore the prospects for observing CP violation in the minimal supersymmetric extension of the Standard Model (MSSM) with six CP-violating parameters, three gaugino mass phases and three phases in trilinear soft supersymmetry-breaking parameters, using the CPsuperH code combined with a geometric approach to maximise CP-violating observables subject to the experimental upper bounds on electric dipole moments. We also implement CP-conserving constraints from Higgs physics, flavour physics and the upper limits on the cosmological dark matter density and spin-independent scattering. We study possible values of observables within the constrained MSSM (CMSSM), the non-universal Higgs model (NUHM), the CPX scenario and a variant of the phenomenological MSSM (pMSSM). We find values of the CP-violating asymmetry A_mathrm{CP} in b rightarrow s gamma decay that may be as large as 3 %, so future measurements of A_mathrm{CP} may provide independent information about CP violation in the MSSM. We find that CP-violating MSSM contributions to the B_s meson mass mixing term Delta M_{B_s} are in general below the present upper limit, which is dominated by theoretical uncertainties. If these could be reduced, Delta M_{B_s} could also provide an interesting and complementary constraint on the six CP-violating MSSM phases, enabling them all to be determined experimentally, in principle. We also find that CP violation in the h_{2,3} tau ^+ tau ^- and h_{2,3} {bar{t}} t couplings can be quite large, and so may offer interesting prospects for future pp, e^+ e^-, mu ^+ mu ^- and gamma gamma colliders.