Minding the gap: Testing natural anomaly-mediated SUSY breaking at high luminosity LHC

While the minimal anomaly-mediated SUSY breaking model (mAMSB) seems ruled out by constraints on Higgs mass, naturalness and wino dark matter, a slightly generalized version dubbed natural AMSB (nAMSB) remains both viable and compelling. Like mAMSB, nAMSB features winos as the lightest gauginos, but unlike mAMSB, nAMSB allows a small μ parameter so that Higgsinos are the lightest of electroweakinos (EWinos). nAMSB spectra depend on the input value of gravitino mass m 3 / 2 , where the lower range of m 3 / 2 is excluded by LHC gluino pair searches while a higher m 3 / 2 band is excluded by LHC limits on wino pair production followed by boosted hadronic wino decays. A remaining intermediate gap in m 3 / 2 values remains allowed by present LHC searches, but appears to be completely explorable by high luminosity upgrades of LHC (HL-LHC). We explore a variety of compelling discovery channels that may allow one to close the intermediate gap in m 3 / 2 values: (1) same-sign diboson + E T (SSdB) production arising from wino pair production, leading to same-sign dileptons plus missing E T , (2) trilepton production arising from wino pair production and (3) soft dilepton plus jet events from Higgsino pair production, (4) top-squark pair production. From our signal-to-background analysis along a nAMSB model line, we expect HL-LHC to either discover or rule out the nAMSB model with 3000 fb − 1 of integrated luminosity.