Bounding the Minimal 331 Model through the Decay B -> X_s gamma

TL;DR

This paper updates the analysis of the B -> X_s gamma decay within the minimal 331 model, highlighting the dominant role of the Higgs sector and deriving bounds on the charged Higgs mass based on the decay's branching ratio.

Contribution

It provides the first detailed analysis of B -> X_s gamma in the minimal 331 model considering recent experimental and theoretical updates, emphasizing the Higgs sector's influence.

Findings

Higgs sector dominates the decay process.

Lower bound on charged Higgs mass derived.

Branching ratio increases for small tan beta.

Abstract

We study the decay B -> X_s gamma within the framework of the minimal 331 model, taking into account both new experimental and theoretical developments that allow us to update and improve on an existing ten year old analysis. In contrast to several other flavor changing observables that are modified already at tree level from a new Z' gauge boson, we have only one loop contributions in this case. Nevertheless, these are interesting, as they may be enhanced and can shed light on the charged gauge boson and Higgs sector of the model. Numerically, we find that the Higgs sector, which is well approximated by a 2 Higgs doublet model (2HDM), dominates, since the gauge contributions are already very strongly constrained. With respect to B -> X_s gamma, the signal of the minimal 331 model is therefore nearly identical to the 2HDM one, which allows us to obtain a lower bound on the charged Higgs mass. Further, we observe, in analogy to the 2HDM model, that the branching fraction can be rather strongly increased for small values of tan beta. Also, we find that B -> X_s gamma has no impact on the bounds obtained on rare K and B decays in an earlier analysis.