Flavour from the Planck scale to the electroweak scale

TL;DR

This paper proposes a flavor theory linking Higgs Yukawa couplings to new scalar particles like leptoquarks and Z' bosons, with implications for explaining anomalies in B-meson decays, depending on the mediator involved.

Contribution

It introduces a model connecting Higgs Yukawa couplings to leptoquarks and Z' bosons via mixing with a vector-like family, exploring their roles in flavor anomalies.

Findings

Leptoquark exchange can significantly contribute to R_{K^{(*)}}.

Z' exchange is constrained by B_s mixing and tau decays.

The model's parameters depend on the mediator's mass scale.

Abstract

We discuss a theory of flavour in which Higgs Yukawa couplings are related to those of the new scalar triplet leptoquark and/or $Z'$ responsible for $R_{K^{(*)}}$, with all couplings arising effectively from mixing with a vector-like fourth family, whose mass may be anywhere from the Planck scale to the electroweak scale for the leptoquarks explanation, but is pinned down to the TeV scale if the $Z'$ exchange plays a role. However, in this particular model, only leptoquark exchange can contribute significantly to $R_{K^{(*)}}$, since $Z'$ exchange is too constrained from $B_s$ mixing and $\tau \rightarrow 3 \mu$, although other Higgs Yukawa matrix structures may allow it.