Flavor Changing Neutral Higgs Couplings and Top-Charm Production at Next Linear Collider

Abstract

We explore the possibility of detecting flavor changing neutral Higgs couplings at the Next Linear Collider (NLC) through $e^{+}{e}^{-}\to {\nu }_e\overline{{\nu }_e}t\bar{c}$. In the framework of a general two-Higgs doublet model, we perform a complete calculation and find that $\sigma (e^{+}{e}^{-}\to {\nu }_e{\nu }_{e}t\bar{c},{\nu }_e\overline{{\nu }_e}\bar{t}c)$ could reach $\sim 9$ fb for $\sqrt{s}=2TeV$. This amounts to an annual production of 500 $t\bar{c}$ plus $\bar{t}c$ pairs at the NLC with an integrated luminosity of 50 fb${}^{-1}$. The dependence of $tc$-production rate on the neutral scalar mixing angle is mild except when ${\sin }^2\alpha \to 0or1$. The $\nu \nu W^{+}{W}^{-}$ background should be manageable after $b$-tagging, while $\nu \nu t\bar{t}$ background should not be a problem when the signal event rate is still interesting. The process, together with $e^{+}{e}^{-}\to {\nu }_e\overline{{\nu }_e}{W}^{+}{W}^{-},{\nu }_e\overline{{\nu }_e}ZZ$ studies, offer the chance of measuring the $t$-$c$-Higgs coupling.

Comments: REVTEX, 18 pages, 7 figures; Report number changed