Flavor-changing neutral Higgs boson couplings and top-quark–charm-quark production at the Next Linear Collider

We explore the possibility of detecting flavor-changing neutral Higgs boson couplings at the Next Linear Collider (NLC) through [Formula presented]. In the framework of a general two-Higgs-doublet model, we perform a complete calculation and find that [Formula presented] could reach [Formula presented] fb for [Formula presented]. This amounts to an annual production of 500 [Formula presented] plus [Formula presented] pairs at the NLC with an integrated luminosity of 50 fb[Formula presented]. The dependence of the [Formula presented]-production rate on the neutral scalar mixing angle is mild except when [Formula presented]. The [Formula presented] background should be manageable after [Formula presented] tagging, while [Formula presented] background should not be a problem when the signal event rate is still interesting. The process, together with [Formula presented] studies, offer the chance of measuring the [Formula presented]Higgs-boson coupling.