Exploring the nearly degenerate stop region with sbottom decays

Abstract

A light stop with mass almost degenerate with the lightest neutralino has important connections with both naturalness and dark matter relic abundance. This region is also very hard to probe at colliders. In this paper, we demonstrate the potential of searching for such stop particles at the LHC from sbottom decays, focusing on two channels with final states 2ℓ + E^(miss)_T and 1bℓ + E^(miss)_T. We found that, if the lightest sbottom has mass around or below 1TeV and has a significant branching ratio to decay to stop and W (b → tW), a stop almost degenerate with neutralino can be excluded up to about 500-600 GeV at the 13TeV LHC with 300 fb^(-1) data. The searches we propose are complementary to other SUSY searches at the LHC and could have the best sensitivity to the stop-bino coannihilation region. Since they involve final states which have already been used in LHC searches, a reinterpretation of the search results already has sensitivity. Further optimization could deliver the full potential of these channels.