B -> D^(*) tau nu and B -> tau nu in chiral U(1)' models with flavored multi Higgs doublets

TL;DR

This paper explores how chiral U(1)' models with multiple Higgs doublets can simultaneously explain anomalies in top quark asymmetry and affect B meson decays, providing new insights into flavor physics.

Contribution

It introduces a model with extra Higgs doublets that links top forward-backward asymmetry to B decay anomalies through flavor-changing Yukawa couplings.

Findings

Extra scalars influence B to D^{(*)} tau nu and B to tau nu decays.

Parameter regions can accommodate large top asymmetry while satisfying B decay constraints.

Charged Higgs effects on top asymmetry are negligible.

Abstract

We discuss semileptonic and leptonic B decays, B to D^{(*)} tau nu and B to tau nu, in the chiral U(1)' models which were proposed by the present authors in the context of the top forward-backward asymmetry (A^t_FB) observed at the Tevatron. In these models, extra Higgs doublets with nonzero U(1)' charges are required in order to make the realistic mass matrix for up-type quarks. Then the extra (pseudo)scalars contribute to A^t_FB with large flavor-changing Yukawa couplings involving top quark. The contribution of the charged Higgs to A^t_FB is negligible, but it may significantly affect B decays: especially, B to D^(*) tau nu and B to tau nu. We investigate constraints on the B decays, based on the recent results in BaBar and Belle experiments, and discuss the possibility that the allowed parameter region in the B decays can achieve large A^t_ FB.