Probing stops in the coannihilation region at the HL-LHC: A comparative study of different processes

Abstract

In the minimal supersymmetric model, the coannihilation of the lighter stop t˜1 and bino-like dark matter χ provides a feasible way to accommodate the correct dark matter relic abundance. In this scenario, due to the compressed masses, t˜1 merely appears as missing energy at the LHC and thus the pair production of t˜1 can only be probed by requiring an associated energetic jet. Meanwhile, since t˜2 and b˜1 are correlated in mass and mixing with t˜1, the production of t˜2t˜2⁎ or b˜1b˜1⁎, each of which dominantly decays into t˜1 plus Z, h or W boson, may serve as a complementary probe. We examine all these processes at the HL-LHC and find that the 2σ sensitivity to χ mass can be as large as about 570 GeV, 600 GeV for mt˜2≲1100 GeV and 1.1 TeV for mb˜1≲1375 GeV from the production process of t˜1t˜1⁎+jet, t˜2t˜2⁎ and b˜1b˜1⁎, respectively.