Implications of b → sμμ anomalies for future measurements of [formula omitted] and [formula omitted

Sébastien Descotes-Genon,Svjetlana Fajfer,Jernej F Kamenik,Martín Novoa-Brunet

doi:10.1016/j.physletb.2020.135769

Abstract

We investigate the consequences of deviations from the Standard Model observed in b→sμμ transitions for flavour-changing neutral-current processes involving down-type quarks and neutrinos. We derive the relevant Wilson coefficients within an effective field theory approach respecting the SM gauge symmetry, including right-handed currents, a flavour structure based on approximate U(2) symmetry, and assuming only SM-like light neutrinos. We discuss correlations among B→K(⁎)νν¯ and K→πνν¯ branching ratios in the case of linear Minimal Flavour Violation and in a more general framework, highlighting in each case the role played by various New Physics scenarios proposed to explain b→sμμ deviations.

Highlights

Recent experimental data in B physics hint toward deviations from Lepton Flavour Universality (LFU) in semi-leptonic decays [1] B(B → Kμμ) B(B → K∗μμ)RK = B(B → Kee), RK∗ = B(B → K∗ee), (1)as measured by LHCb [2,3,4] at significances from 2.3σ to 2.6σ
We have investigated the consequences of deviations from the Standard Model (SM) observed in b → sμμ transitions for FCNC processes involving down-type quarks and neutrinos
Motivated by the results from the global fits to b → s observables as well as measurements and bounds on FCNC processes with neutrinos, we have considered a general EFT description of FCNC transitions in terms of SU (2)L gauge invariant operators including those with right-handed quarks and charged leptons

Summary

Introduction

Recent experimental data in B physics hint toward deviations from Lepton Flavour Universality (LFU) in semi-leptonic decays [1]. The Belle II collaboration plans to observe these three decay modes with about 10 ab−1 of data, while the sensitivities to the SM branching ratio will reach a precision of about. The experimental limits at 90% CL for the branching ratios were obtained by the E949 experiment B(K+ → π+νν)exp < 3.35 × 10−10 [24, 25] with a recent update from the NA62 collaboration B(K+ → π+νν)exp < 2.24 × 10−10 [26], while KOTO presented preliminary results indicating B(KL → π0νν)exp = 2.1+−21..01((+−41..17)) × 10−9 [27].

Findings

LαL γ μ σ a LβL

Conclusions