Implications of four-top and top-pair studies on triple-top production

Multi-top quark production is a staple program at the LHC. Single-top and t (t) over bar productions are studied extensively, while current efforts are zooming in on four-top search, where the Standard Model (SM) cross section is at O(10) fb. In contrast, only at the fb level in SM, triple-top production has not been targeted for study so far. But such a small cross section makes it a unique probe for New Physics. Without the usual discrete Z(2) symmetry, the general two Higgs doublet model (g2HDM) can naturally raise the triple-top production to pb level. We illustrate how certain signal regions of four-top search can be utilized to constrain triple-top production, but urge a dedicated search. As an aside, we note that the CMS study at 13 TeV of scalar t (t) over bar resonance interfering with QCD production background indicate some activity at 400GeV. We comment that this could be explained in principle in g2HDM via the extra top Yukawa coupling. (C) 2019 The Authors. Published by Elsevier B.V.