Probing flavor changing neutral Higgs couplings at LHC

Uniquely heavy with mass at the weak scale, the top quark may have large flavor changing couplings to Higgs bosons that are as yet unexplored. We show that such couplings could be directly probed at the LHC through the parton subprocess c(c)g → t(t)A0, where the pseudoscalar A0 subsequently decays into tc or tc, giving rise to the intriguing final state of like sign top quark pairs. After demanding ℓ±ℓ±, missing energy and two b-jets, the major background turns out to be qq′ → Wtt, which can be partially suppressed by jet counting. The signal can then manifest itself in the asymmetry of numbers of ℓ+ℓ+ and ℓ−ℓ− events. To further improve the signal over background, efficient t vs. t tagging methods should be developed.