Four tops for LHC

We design a search strategy for the Standard Model t (t) over bart (t) over bar production at the LHC in the same-sign dilepton and trilepton channels. We study different signal features and, given the small expected number of signal events, we scrutinize in detail all reducible and irreducible backgrounds. Our analysis shows that by imposing a basic set of jet and lepton selection criteria, the SM pp -> t (t) over bart (t) over bart process could be evidenced in the near future, within Run-II, when combining both multi-lepton search channels. We argue that this search strategy should also be used as a guideline to test New Physics coupling predominantly to top-quarks. In particular, we show that a non-resonant New Physics enhancement in the four-top final state would be detectable through this search strategy. We study two top-philicsimplified models of this kind, a neutral scalar boson and a Z', and present current and future exclusion limits on their mass and couplings. (C) 2016 The Authors. Published by Elsevier B.V.