A new look at $b\to s$ observables in 331 models

Abstract

Flavour changing neutral current (FCNC) processes are described by loop diagrams in the Standard Model (SM), while in 331 models, based on the gauge group $\text{SU}(3{)}_C\times \text{SU}(3{)}_L\times \text{U}(1{)}_X$, they are dominated by tree-level exchanges of a new heavy neutral gauge boson $Z^{\prime }$. Exploiting this feature, observables related to FCNC decays of $K$, $B_d$ and $B_s$ mesons can be considered in several variants of 331 models. The variants are distinguished by the value of a parameter $\beta$ that plays a key role in this framework. Imposing constraints on the $\Delta F=2$ observables, we select possible ranges for the mass of the $Z^{\prime }$ boson in correspondence to the values $\beta =\pm k/\sqrt{3}$, with $k=1,2$. The results are used to determine the impact of 331 models on $b\to s$ processes and on the correlations among them, in the light of new experimental data recently released.

Comments: latex, 26 pages, 8 figures