Stop searches in flavourful supersymmetry

Abstract

Natural realisations of supersymmetry require light stops ${\tilde t}_1$, making them a prime target of LHC searches for physics beyond the Standard Model. Depending on the kinematic region, the main search channels are ${\tilde t_1}\to t \tilde \chi^0_1$, ${\tilde t_1}\to W b \tilde \chi^0_1$ and ${\tilde t_1}\to c \tilde \chi^0_1$. We first examine the interplay of these decay modes with ${\tilde c_1}\to c \tilde \chi^0_1$ in a model-independent fashion, revealing the existence of large regions in parameter space which are excluded for any ${\tilde t_1}\to c \tilde \chi^0_1$ branching ratio. This effect is then illustrated for scenarios with stop-scharm mixing in the right-handed sector, where it has previously been observed that the stop mass limits can be significantly weakened for large mixing. Our analysis shows that once the LHC bounds from ${\tilde c_1}\to c \tilde \chi^0_1$ searches are taken into account, non-zero stop-scharm mixing leads only to a modest increase in the allowed regions of parameter space, with large areas excluded for arbitrary mixing angles.