Stop searches in flavourful supersymmetry

Abstract

Natural realisations of supersymmetry require light stops 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 t˜1→tχ˜10, t˜1→Wbχ˜10 and t˜1→cχ˜10. We first examine the interplay of these decay modes with c˜1→cχ˜10 in a model-independent fashion, revealing that a large parameter space region with stop mass values mt˜1 up to 530 GeV is excluded for any t˜1→cχ˜10 branching ratio by LHC Run I data. The impact of c˜1→cχ˜10 decays is further 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 c˜1→cχ˜10 bounds are taken into account, non-zero stop-scharm mixing can lead to an increase in the allowed parameter space by at most 35%, with large areas excluded for arbitrary mixing.