Physical constraints derived from FCNC in the 3-3-1-1 model

TL;DR

This paper analyzes flavor-changing neutral currents in the 3-3-1-1 model, establishing constraints from meson oscillations and exploring their effects on various decay processes, with a focus on new physics scale bounds.

Contribution

It clarifies the sources of FCNCs at tree-level in the 3-3-1-1 model and derives a tighter lower bound on the new physics scale based on experimental data.

Findings

Lower bound on new physics scale is >12 TeV.

Tree-level FCNCs have negligible impact on certain B meson decay branching ratios.

Charged Higgs diagrams enhance the $b ightarrow s \, ext{gamma}$ decay.

Abstract

We investigate several phenomena related to FCNCs in the $\text{3-3-1-1}$ model. The sources of FCNCs at the tree-level from both the gauge and Higgs sectors are clarified. Experiments on the oscillation of mesons most stringently constrain the tree-level FCNCs. The lower bound on the new physics scale is imposed more tightly than in the previous, $\text{M}_{\text{new}}>12 $ \text{TeV}. Under this bound, the tree-level FCNCs make a negligible contribution to the $\text{Br}(B_s \rightarrow \mu^+ \mu^-)$, $\text{Br}(B \rightarrow K^{*} \mu^+ \mu^-)$ and $\text{Br}(B^{+}\rightarrow K^{+}\mu^{+}\mu^{-})$. The branching ratio of radiative decay $b \rightarrow s \gamma$ is enhanced by the ratio $\frac{v}{u}$ via diagrams with the charged Higgs mediation. In contrast, the charged currents of new gauge bosons significantly contribute to the decay process $\mu \rightarrow e \gamma$.