Single top squark production as a probe of natural supersymmetry at the LHC

Light top squarks (stops) and light higgsinos are the key features of natural supersymmetry (SUSY), where the higgsinos χ∼1± and χ∼1,20 are nearly degenerate and act as the missing transverse energy (ET) at the LHC. Besides the pair production via strong interaction, the stop can be produced via the electroweak interaction. The determination of the electroweak properties of the stop is an essential task for the LHC and future colliders. So, in this paper, we investigate the single stop (t∼1) production pp→t∼1+ET via the electroweak interaction in natural SUSY at the LHC, which gives the monotop signature t+ET from t∼1→tχ∼1,20 or the monobottom signature b+ET from t∼1→bχ∼1+. We perform Monte Carlo simulations for these signatures and obtain the observations: (1) The signal b+ET has a better sensitivity than t+ET for probing natural SUSY; (2) the parameter region with a higgsino mass 100 GeVμ 225 GeV and stop mass mt∼1620 GeV can be probed through such single stop production with S/B>3 and 4% S/B19% at the 14 TeV LHC with an integrated luminosity of 3000 fb-1.