Abstract
We perform a model-independent global fit to brightarrow sell ^+ell ^- observables to confirm existing New Physics (NP) patterns (or scenarios) and to identify new ones emerging from the inclusion of the updated LHCb and Belle measurements of R_K and R_{K^*}, respectively. Our analysis, updating Refs. Capdevila et al. (J Virto JHEP 1801:093, 2018) and Algueró et al. (J Matias Phys Rev D 99(7):075017, 2019) and including these new data, suggests the presence of right-handed couplings encoded in the Wilson coefficients {{{mathcal {C}}}}_{9'mu } and {{{mathcal {C}}}}_{10'mu }. It also strengthens our earlier observation that a lepton flavour universality violating (LFUV) left-handed lepton coupling ({{{mathcal {C}}}}_{9mu }^{mathrm{V}}=-,{{{mathcal {C}}}}_{10mu }^{mathrm{V}}), often preferred from the model building point of view, accommodates the data better if lepton-flavour universal (LFU) NP is allowed, in particular in {{{mathcal {C}}}}_{9}^{mathrm{U}}. Furthermore, this scenario with LFU NP provides a simple and model-independent connection to the brightarrow ctau nu anomalies, showing a preference of approx 7,sigma with respect to the SM. It may also explain why fits to the whole set of brightarrow sell ^+ell ^- data or to the subset of LFUV data exhibit stronger preferences for different NP scenarios. Finally, motivated by Z^prime models with vector-like quarks, we propose four new scenarios with LFU and LFUV NP contributions that give a very good fit to data.
Highlights
Motivated by the new emerging directions in the lepton flavour universality violating (LFUV) case we extend our analysis of New Physics (NP) scenarios to allow for the presence of lepton flavour universality (LFU) NP right handed-currents (RHC)
Including recent updates (RK, RK ∗ and B(Bs → μ+μ−)) our global model-independent analysis yields a very similar picture to the one previously found in Refs. [1,2] for the various NP scenarios of interest with some important peculiarities
In presence of LFUV NP contributions only, the 1D fits to “All” observables remain basically unchanged showing the preference for C9NμP scenario over C9NμP = − C1N0Pμ
Summary
Framework (see, for instance, [1,2,3]), where all short-distance physics (including NP) is encoded in Wilson coefficients, i.e. the coefficients of higher-dimension operators. [1], our analysis includes the latest update of P4,5 from the Belle collaboration [12] where the muon and electron modes are considered separately (averaging charged and neutral modes), superseding the previous measurement in Ref. [13] where an average over both leptonic modes is presented This allows us to include an additional measurement P5μ (exhibiting a 2.6 σ discrepancy with respect to the SM) as well as the LFUV observable Q5 in our analysis An appendix is devoted to the description of the correlations obtained for the various Wilson coefficients in the most relevant scenarios considered in this article
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