Likelihood analysis of the pMSSM11 in light of LHC 13-TeV data

Abstract

We use MasterCode to perform a frequentist analysis of the constraints on a phenomenological MSSM model with 11 parameters, the pMSSM11, including constraints from $$\sim 36$$ /fb of LHC data at 13 TeV and PICO, XENON1T and PandaX-II searches for dark matter scattering, as well as previous accelerator and astrophysical measurements, presenting fits both with and without the $$(g-2)_\mu $$ constraint. The pMSSM11 is specified by the following parameters: 3 gaugino masses $$M_{1,2,3}$$ , a common mass for the first-and second-generation squarks $$m_{\tilde{q}}$$ and a distinct third-generation squark mass $$m_{\tilde{q}_3}$$ , a common mass for the first-and second-generation sleptons $$m_{\tilde{\ell }}$$ and a distinct third-generation slepton mass $$m_{\tilde{\tau }}$$ , a common trilinear mixing parameter A, the Higgs mixing parameter $$\mu $$ , the pseudoscalar Higgs mass $$M_A$$ and $$\tan \beta $$ . In the fit including $$(g-2)_\mu $$ , a Bino-like $$\tilde{\chi }^0_{1}$$ is preferred, whereas a Higgsino-like $$\tilde{\chi }^0_{1}$$ is mildly favoured when the $$(g-2)_\mu $$ constraint is dropped. We identify the mechanisms that operate in different regions of the pMSSM11 parameter space to bring the relic density of the lightest neutralino, $$\tilde{\chi }^0_{1}$$ , into the range indicated by cosmological data. In the fit including $$(g-2)_\mu $$ , coannihilations with $$\tilde{\chi }^0_{2}$$ and the Wino-like $$\tilde{\chi }^\pm _{1}$$ or with nearly-degenerate first- and second-generation sleptons are active, whereas coannihilations with the $$\tilde{\chi }^0_{2}$$ and the Higgsino-like $$\tilde{\chi }^\pm _{1}$$ or with first- and second-generation squarks may be important when the $$(g-2)_\mu $$ constraint is dropped. In the two cases, we present $$\chi ^2$$ functions in two-dimensional mass planes as well as their one-dimensional profile projections and best-fit spectra. Prospects remain for discovering strongly-interacting sparticles at the LHC, in both the scenarios with and without the $$(g-2)_\mu $$ constraint, as well as for discovering electroweakly-interacting sparticles at a future linear $$e^+ e^-$$ collider such as the ILC or CLIC.