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

Abstract

Multi-top quark production is a staple program at the LHC. Single-top and tt¯ 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 Z2 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 tt¯ resonance interfering with QCD production background indicate some activity at 400 GeV. We comment that this could be explained in principle in g2HDM via the extra top Yukawa coupling.