Same-sign top pair plus W production in flavor changing vector and scalar models

Abstract

We investigate the prospect of the LHC for discovering new physics effects via new strategies in the same-sign top pair and same-sign top pair associated with a W boson signatures. Significant enhancement in production of same-sign top quarks (plus a W boson) is a joint property of several models beyond the standard model. We concentrate on the leptonic (electron and muon) decay of the top quarks and study the exclusion reach of the LHC data for a simplified model approach where top quark flavor changing could occur through a Z or a neutral scalar φ exchange. Less background contributions and clean signature are the advantages of the leptonic decay mode of the top quarks in the same-sign production processes. A combination is performed on both same-sign top pair and same-sign top pair plus a W boson production modes which enables us to reach a large fraction of the model parameter space. Assuming the couplings of new physics of the order of 10 −2 , the mass of a flavor changing Z or a neutral scalar above 1 TeV could be excluded. We propose a momentum dependent charge asymmetry and angular observables in the same-sign top process which provide the possibility of separation of new physics signal from the SM backgrounds as well as discrimination of the flavor changing tuX from tcX, where X = Z , φ.

Investigating Top-Higgs FCNC Couplings at the FCC-hh

“…For more luminosity results will be enhanced obviously. In literature our results are compatible with other phenomenological results [38][39][40][41] (Bear in mind that our effective Lagrangian is so restrictive in general, thus limits can be imporeved directly by 4 times when we consider coupling constants).…”

What can we learn from triple top-quark production?

“…Even worse, some searching programs of top FVNI effects cannot fully confirm its existence. For example, the same-sign top-quark pair (tt=tt) production [11][12][13], often thought as a gold channel of probing top quark FVNI interactions, can be mimicked by a color sextet scalar or vector [14,15].…”

Probing top changing neutral Higgs couplings at colliders

“…m k Same-sign top was advocated 70 to appear with even 1 fb −1 LHC data due to some Tevatron "anomaly", but this was quickly ruled out. 71,72 Same-sign top production has also been advocated recently with flavor-changing Z , 73,74 as well as neutral scalar φ exchange. 73 l This is in part because SM 4t cross section 75,78 at ∼ 12 fb is an order of magnitude larger than 3t in SM, hence can be measured sooner if SM holds true.…”