Plan B: New Z^′ models for b→ sl⁺l^- anomalies

2023/06/14 by Allanach, Ben, Mullin, Anna · 2 citations
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph)

paper · doi:10.48550/arxiv.2306.08669

Abstract

Measurements of b → s μ⁺ μ^- transitions indicate that there may be a new physics field coupling to di-muon pairs associated with the b to s flavour transition. Including the 2022 LHCb reanalysis of R_K and R_K^∗, one infers that there may also be associated new physics in b→ e⁺ e^- transitions. Here, we examine the extent of the statistical preference for Z^′ models coupling to di-electron pairs taking into account the relevant constraints, in particular from experiments at LEP-2. We identify an anomaly-free set of models which interpolates between the Z^′ not coupling to electrons at all, to one in which there is an equal Z^′ coupling to muons and electrons (but where in all models in the set, the Z^′ boson can mediate b→ μ⁺ μ^- transitions). A 3B₃-L_e-2L_μ model provides a close-to-optimal fit to the pertinent measurements along the line of interpolation. We have (re-)calculated predictions for the relevant LEP-2 observables in terms of dimension-6 SMEFT operators and put them into the \tt flavio computer program, so that they are available for global fits.

Cited by

• Prospects for Measuring CP-Violation in B_s⁰ → ϕμ⁺μ^- via Time-Dependent Angular Analysis
• First measurement of time-dependent CP violation in the flavor-changing neutral-current decay B⁰→ K_S⁰μ⁺μ^-

Related

• LHC di-lepton searches for Z^′ bosons which explain measurements of b → s l⁺l^- transitions
• A B-anomaly motivated Z^′ boson at the energy and precision frontiers
• The Plan B Model: Z^′ collider phenomenology and discovery prospects
• M_W helps select Z^′ models for b → s ℓ ℓ anomalies
• Can the muon anomalous magnetic moment and the B anomalies be simultaneously explained in a minimally extended Z^′ model?