$B$ meson anomalies within the triplet vector boson model to the light of recent measurements from LHCb

TL;DR

This paper updates the triplet vector boson (TVB) model as an explanation for B meson anomalies using recent LHCb data, performing a global fit and analyzing compatibility with collider constraints.

Contribution

It provides an updated global analysis of the TVB model incorporating the latest experimental data and explores its viability in explaining B meson anomalies.

Findings

A 1 TeV TVB can explain anomalies with recent LHCb data.

The model is consistent with some measurements but conflicts with others when considering all data.

Future measurements are needed to resolve current tensions.

Abstract

The triplet vector boson (TVB) is a simplified new physics model involving massive vector bosons transforming as a weak triplet vector. Such a model has been proposed as a combined explanation of the anomalous $b \to s\mu^+\mu^-$ and $b \to c \tau\bar{\nu}_\tau$ data (the so-called $B$ meson anomalies). In this work, we carry out an updated view of the TVB model by incorporating the most recent 2022 and 2023 LHCb measurements on the lepton flavor universality ratios $R(D^{(\ast)}) = {\rm BR}(B \to D^{(\ast)}\tau \bar{\nu}_\tau)/{\rm BR}(B \to D^{(\ast)}\ell^\prime \bar{\nu}_{\ell^\prime})$, $R(\Lambda_c) = {\rm BR}(\Lambda_b \to \Lambda_c\tau\bar{\nu}_\tau)/{\rm BR}(\Lambda_b \to \Lambda_c\mu\bar{\nu}_\mu)$, and $R_{K^{(\ast)}} = {\rm BR}(B \to K^{(\ast)}\mu^+\mu^-)/{\rm BR}(B \to K^{(\ast)}e^+e^-)$. We perform a global fit to explore the allowed parameter space by the new data and all relevant low-energy flavor observables. Our results are confronted with the recent high-mass dilepton searches at the Large Hadron Collider (LHC). We find that for a heavy TVB mass of 1 TeV a common explanation of the $B$ meson anomalies is possible for all data with the recent LHCb measurements on $R(D^{(\ast)})$, in consistency with LHC constraints. However, this framework is in strong tension with LHC bounds when one considers all data along with the world average values (BABAR, Belle, and LHCb) on $R(D^{(\ast)})$. Future measurements will be required in order to clarify such a situation. In the end, the implications of our phenomenological analysis of the TVB model to some known flavor parametrizations are also discussed.