B anomalies under the lens of electroweak precision

Abstract

The measurements carried out at LEP and SLC projected us into the precision era of electroweak physics. This has also been relevant in the theoretical interpretation of LHCb and Belle measurements of rare B semileptonic decays, paving the road for new physics with the inference of lepton universality violation in $$ {R}_{K^{\left(\ast \right)}} $$ R K ∗ ratios. The simplest explanation of these flavour anomalies — sizeable one-loop contributions respecting Minimal Flavour Violation — is currently disfavoured by electroweak precision data. In this work, we discuss how to completely relieve the present tension between electroweak constraints and one-loop minimal flavour violating solutions to $$ {R}_{K^{\left(\ast \right)}} $$ R K ∗ . We determine the correlations in the Standard Model Effective Field Theory that highlight the existence of such a possibility. Then, we consider minimal extensions of the Standard Model where our effective-field-theory picture can be realized. We discuss how these solutions to b → sℓℓ anomalies, respecting electroweak precision and without any new source of flavour violation, may point to the existence of a Z′ boson at around the TeV scale, within the discovery potential of LHC, or to leptoquark scenarios.

Universal scalar leptoquark action for matching

“…S 3 3 3 We have chosen to study the decoupling of heavy scalar leptoquark fields for two main reasons: first, there is a plethora of interesting BSM phenomena associated to them, i.e. from neutrino masses and proton decay [38], to possible interpretation of recent flavour anomalies and enhanced anomalous magnetic moment of the muon [39][40][41][42][43][44], and second, leptoquark fields are naturally embedded in Grand Unified Theories (GUTs) which may be in turn linked to even more fundamental theories.…”

Revisiting electroweak radiative corrections to b → sℓℓ in SMEFT

“…This is contrasted to the analyses in refs. [10][11][12], where the contributions are generated by the RG corrections, i.e., the logarithmic term by assuming that the input scale of the SMEFT operators are much larger than the EW scale and discarding the finite terms. Consequently, our results differ from them by factors of O(1).…”

“…On the other hand, refs. [10][11][12] has attempted to evaluate those effects by solving the renormalization group equations (RGEs) especially of the SM Yukawa matrices. In contrast, we study general SMEFT operators which are relevant for b → s .…”

“….31) Similarly to the case of (C Hu ) ij , eqs. (3.16),(3.17), and (3.39) are enough to derive the flavor-changing corrections, which are assembled as12 …”

Global fits of third family hypercharge models to neutral current B-anomalies and electroweak precision observables

“…The connection between the EWPOs and minimal flavour-violating one-loop induced NCBAs has recently been addressed in Ref [90],. encoding the inputs in the SMEFT framework.…”