PROBING FLAVOR-CHANGING NEUTRAL HIGGS COUPLINGS AT LHC

Uniquely heavy with mass at the weak scale, the top quark may have lar ge flavor changing couplings to Higgs bosons that are as yet unexplore d. We show that such couplings could be directly probed at the LHC thr ough the parton subprocess c((c) over bar)g --> t((t) over bar)A(0), w here the pseudoscalar A(0) subsequently decays into t (c) over bar or (t) over bar c, 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 q (q) over bar' --> Wt ( t) over bar, which can be partially suppressed by jet counting. The si gnal can then manifest itself in the asymmetry of numbers of l(+)l(+) and l(-)l(-) events. To further improve the signal over background, ef ficient t vs. (t) over bar tagging methods should be developed. (C) 19 97 Elsevier Science B.V.