Likelihood analysis of the sub-GUT MSSM in light of LHC 13-TeV data

We describe a likelihood analysis using MasterCode of variants of the MSSM in which the soft supersymmetry-breaking parameters are assumed to have universal values at some scale M_in below the supersymmetric grand unification scale M_GUT , as can occur in mirage mediation and other models. In addition to M_in , such ‘sub-GUT’ models have the 4 parameters of the CMSSM, namely a common gaugino mass m_1/2 , a common soft supersymmetry-breaking scalar mass m_0 , a common trilinear mixing parameter A and the ratio of MSSM Higgs vevs tanβ , assuming that the Higgs mixing parameter μ > 0 . We take into account constraints on strongly- and electroweakly-interacting sparticles from ∼ 36 /fb of LHC data at 13 TeV and the LUX and 2017 PICO, XENON1T and PandaX-II searches for dark matter scattering, in addition to the previous LHC and dark matter constraints as well as full sets of flavour and electroweak constraints. We find a preference for M_in∼ 10^5 to 10^9 GeV , with M_in∼ M_GUT disfavoured by Δχ ^2 ∼ 3 due to the BR(B_s, d→μ ^+μ ^-) constraint. The lower limits on strongly-interacting sparticles are largely determined by LHC searches, and similar to those in the CMSSM. We find a preference for the LSP to be a Bino or Higgsino with m_χ̃^0_1∼ 1 TeV , with annihilation via heavy Higgs bosons H / A and stop coannihilation, or chargino coannihilation, bringing the cold dark matter density into the cosmological range. We find that spin-independent dark matter scattering is likely to be within reach of the planned LUX-Zeplin and XENONnT experiments. We probe the impact of the (g-2)_μ constraint, finding similar results whether or not it is included.