Eur. Phys. J. C (2022) 82: 966
https://doi.org/10.1140/epjc/s10052-022-10916-7

Regular Article - Theoretical Physics

New physics in $\text{b}\to \text{s}$ transitions in the MF331 model

¹ Institute of Physics, VAST, 10 Dao Tan, Ba Dinh, Hanoi, Vietnam
² Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam
³ Faculty of Natural Sciences and Technology Tay Bac University, Quyet Tam Ward, Son La, Son La, Vietnam

^c dthuong@iop.vast.vn

Received: 9 May 2022
Accepted: 13 October 2022
Published online: 29 October 2022

Abstract

There are two sources that help to explain the ${\text{R}}_{\text{K}}$, ${\text{R}}_{{\text{K}}^{\ast }}$ anomalies in the MF331 model. The first is non-LFUV couplings of the new neutral gauge boson ${\text{Z}}^{\prime }$ with leptons, ${\text{g}}^{{\text{Z}}^{\prime }}(e)\ne {\text{g}}^{{\text{Z}}^{\prime }}(\mu ,\tau )$, which causes the ${\text{R}}_{\text{K}}$, ${\text{R}}_{{\text{K}}^{\ast }}$ anomalies via ${\text{Z}}^{\prime }$-penguin diagrams involving newly charged gauge bosons ${\text{X}}_{\mu }^{\pm }$, and exotic U-quarks. The second is the contribution from the box diagram only for the first generation of leptons. We show that the penguin diagrams can not explain ${\text{R}}_{\text{K}}$, ${\text{R}}_{{\text{K}}^{\ast }}$ anomalies, and that the box diagram is required. The experimental constraints for ${\text{R}}_{\text{K}}$ and ${\text{R}}_{{\text{K}}^{\ast }}$ result in new particle mass degeneracy. The contributions of NP to the branching ratios $\text{Br}({\text{B}}_{\text{s}}\to {\mu }^{+}{\mu }^{-}),\text{Br}(\text{b}\to s\gamma )$ predict results that agree with the experimental limits in the allowed region of the NP scale.