Light sfermion interplay in the 125 GeV MSSM Higgs production and decay at the LHC

Abstract

We study the effects from light sfermions on the lightest Higgs boson production and decay at the Large Hadron Collider (LHC) within the Minimal Supersymmetric Standard Model (MSSM). We find that the scenario with light coloured sfermions -- stops or sbottoms -- has the potential to explain a non-universal alteration, as hinted by LHC data, of the gluon-gluon Fusion ($\mu_{ggF}$) with respect to the Vector Boson Fusion ($\mu_{VBF}$) event rates and, in particular, can predict $\frac{\mu_{VBF}}{\mu_{ggF}}>1$ for all Higgs boson decay channels in large areas of the parameter space. We also find that the scenario with a light stop/sbottom can be complemented by the scenario in which the total Higgs width, $\Gamma_{\rm tot}$, is reduced due to a suppressed Yukawa coupling $Y_b$. In this case, the reduction of the Higgs production rates in the $ggF$ process which occurs in the maximal mixing scenario is compensated by the reduction of the $H\to b\bar{b}$ partial decay width, the largest component of $\Gamma_{\rm tot}$. Furthermore, we highlight the fact that, in the light stop/sbottom scenario, event rates with the Higgs boson decaying to a $b\bar{b}$ final state are predicted to be essentially below unity. Therefore, during the future LHC runs, the measurement of $h\to b\bar{b}$ final states is a matter of special importance. Amongst all viable MSSM configurations that we study (including revisiting a light stau solution), we emphasise most the scenario with a light stop, as the latter is also motivated by Dark Matter and Electro-Weak baryogenesis. We also perform fits of the MSSM against the LHC data, emphasising the fact that in most cases these are better than for the SM.