Sbottom discovery via mixed decays at the LHC

In the search for the bottom squark (sbottom) in supersymmetry (SUSY) at the LHC, the common practice has been to assume a 100% decay branching fraction for a given search channel. In realistic minimal supersymmetric Standard Model scenarios, there are often more than one significant decay modes to be present, which significantly weaken the current sbottom search limits at the LHC. On the other hand, the combination of the multiple decay modes offers alternative discovery channels for sbottom searches. In this paper, we present the sbottom decays in a few representative mass parameter scenarios. We then analyze the sbottom signal for the pair production in QCD with one sbottom decaying via b→bχ10, bχ20, and the other one decaying via b→tχ1±. With the gaugino subsequent decaying to gauge bosons or a Higgs boson χ20→Zχ10, hχ10 and χ1±→W±χ10, we study the reach of those signals at the 14 TeV LHC with 300 fb-1 integrated luminosity. For a left-handed bottom squark, we find that a mass up to 920 GeV can be discovered at 5σ significance for 250 GeV<mχ10<350 GeV, or excluded up to 1050 GeV at the 95% confidence level for the h channel (μ>0); similarly, it can be discovered up to 840 GeV, or excluded up to 900 GeV at the 95% confidence level for the Z channel (μ<0). The top squark reach is close to that of the bottom squark. The sbottom and stop signals in the same SUSY parameter scenario are combined to obtain the optimal sensitivity, which is about 150 GeV better than the individual reach of the sbottom or stop. For a right-handed bottom squark with the bb∗→bχ10, tχ1± channel, we find that the sbottom mass up to 880 GeV can be discovered at 5σ significance, or excluded up to 1060 GeV at the 95% confidence level.