Implications for new physics in $$b\rightarrow s \mu \mu $$ transitions after recent measurements by Belle and LHCb

Abstract

We present a Bayesian analysis of the implications for new physics in semileptonic b → s transitions after including new measurements of R K at LHCb and new determinations of R K * and R K * + at Belle. We perform global fits with 1, 2, 4, and 8 input Wilson coefficients, plus one CKM nuisance parameter to take into account uncertainties that are not factorizable. We infer the 68% and 95.4% credibility regions of the marginalized posterior probability density for all scenarios and perform comparisons of models in pairs by calculating the Bayes factor given a common data set. We then proceed to analyzing a few well-known BSM models that can provide a high energy framework for the EFT analysis. These include the exchange of a heavy Z boson in models with heavy vector-like fermions and a scalar field, and a model with scalar leptoquarks. We provide predictions for the BSM couplings and expected mass values.

∆Ms theory precision confronts flavour anomalies

“…On the other hand, the recent update of R K at Moriond 2019 [42] favours a non-zero RH quark current contribution, as widely discussed in the literature since then (see e.g. [54][55][56][57][58][59][60]). There is however a problem with this solution, which is that in our Z model, at the leading order in the NP contribution, the behaviour can be written as has shrunk by only a small amount, and so our benchmark point is only marginally more favoured.…”

“…Intriguingly, one obtains a very good description of the b → s data by allowing new physics only in a single combination of Wilson coefficients (for recent fits see e.g. [54][55][56][57][58][59][60]). The best-fit scenario δC µ 9 = −δC µ 10 ≈ −0.53 ± 0.08 of [54] corresponds to an effective operator with left-handed (LH) quark and muon currents and we consider its interplay with ∆M s in Section 3.4.…”

Explaining b→sℓ+ℓ− data by sneutrinos in the R -parity violating MSSM

“…Finally, LHCb has also observed a 3.3σ deficit in the B 0 s → ϕμ þ μ − decay [20,21]. Motivated by these deviations and using the other available data on such rare b → sl þ l − transitions, many global analyses have been carried out [19,[22][23][24][25][26][27][28], finding that a negative shift in a single Wilson coefficient of local operator like O μμ 9 ¼ ðsγ α P L bÞðμγ α μÞ or O μμ LL ¼ ðsγ α P L bÞðμγ α P L μÞ leads to a consistent description of the data, with the corresponding best-fit point can improve the fit to the data by more than 5σ compared to the SM. Furthermore, the operator O μμ LL performs better than O μμ 9 , mainly because there is now ∼2σ tension in the branching fraction of B s → μ þ μ − [22,[29][30][31][32][33][34], which is not affected by O μμ 9 .…”

Complete vectorlike fourth family and new U(1)′ for muon anomalies

“…It is interesting that all the observables for b → s + − can be explained by New Physics (NP) contributions to the effective Hamiltonian [18,19], The analyses before Moriond 2019 [20][21][22][23][24][25][26][27][28] and after Moriond 2019 [29][30][31][32][33][34][35][36] show that several patterns of NP contributions explain the discrepancies significantly better than the SM. In all cases, there should be a sizable negative contribution to C µ 9 .…”