We present a detailed discussion of the current theoretical and experimental situation of the anomaly in the angular distribution of B → K * (→ Kπ)µ + µ − , observed at LHCb in the 1 fb −1 dataset and recently confirmed by the 3 fb −1 dataset. The impact of this data and other recent measurements on b → s + − transitions ( = e, µ) is considered. We review the observables of interest, focusing on their theoretical uncertainties and their sensitivity to New Physics, based on an analysis employing the QCD factorisation approach including several sources of hadronic uncertainties (form factors, power corrections, charmloop effects). We perform fits to New Physics contributions including experimental and theoretical correlations. The solution that we proposed in 2013 to solve the B → K * µ + µ − anomaly, with a contribution C NP 9 −1, is confirmed and reinforced. A wider range of New-Physics scenarios with high significances (between 4 and 5 σ) emerges from the fit, some of them being particularly relevant for model building. More data is needed to discriminate among them conclusively. The inclusion of b → se + e − observables increases the significance of the favoured scenarios under the hypothesis of New Physics breaking lepton flavour universality. Several tests illustrate the robustness of our conclusions.

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We present a global analysis of the B ! K à ð! KÞ þ À decay using the recent LHCb measurements of the primary observables P 1;2 and P 0 4;5;6;8 . Some of them exhibit large deviations with respect to the Standard Model (SM) predictions. We explain the observed pattern of deviations through a large new physics contribution to the Wilson coefficient of the semileptonic operator O 9 . This contribution has an opposite sign to the SM one, i.e., reduces the size of this coefficient significantly. A good description of data is achieved by allowing for new physics contributions to the Wilson coefficients C 7 and C 9 only. We find a 4:5 deviation with respect to the SM prediction, combining the large-recoil B ! K à ð! KÞ þ À observables with other radiative processes. Once low-recoil observables are included the significance gets reduced to 3:9. We have tested different sources of systematics, none of them modifying our conclusions significantly. Finally, we propose additional ways of measuring the primary observables through new foldings.The four-body B ! K à ð! KÞ þ À decay and its plethora of different observables [1-15] is becoming one of the key players not only in our search for new physics (NP) in the flavor sector but also to guide us in the construction of viable new models, which explains the remarkable experimental effort devoted to its precise measurement [16][17][18][19][20]. In the effective Hamiltonian approach used to analyze radiative decays at low energies, one of the most prominent virtues of this decay is the capacity to unveil NP contributions inside the short distance Wilson coefficients, denotedi , not only for the Standard Model (SM) electromagnetic and dileptonic operators(with the usual P L;R chirality projection operators) but also for the chirally flipped operators O i 0 as well as the scalar and pseudoscalar operators O S;P;S 0 ;P 0 . Among these, the only non-negligible Wilson coefficients in the SM are C SM 7eff;9;10 ð b Þ ¼ ðÀ0:29; 4:07; À4:31Þ at b ¼ 4:8 GeV. The correlations between the Wilson coefficients constitute a unique test ground to find consistent patterns pointing towards specific NP models.However, the presence of hadronic effects can easily hide a NP signal. For this reason, it is essential to design an optimized basis of observables, easy to measure, with low hadronic and high NP sensitivities. In Refs. [15,21] we proposed such a basis, consisting of P 1;2;3 and P 0 4;5;6 (primary observables with a low sensitivity to form-factor uncertainties at low dilepton invariant mass q 2 ), together with F L (or A FB ) and dÀ=dq 2 (containing large uncertainties but required to complete the basis).There has been an evolution in the type of observables measured by LHCb. It started with the set of observables A FB , F L and S 3 [19], all of them rather sensitive to hadronic uncertainties. The experimental results pointed towards a scenario consistent with the SM, but with small deviations in A FB (in both the q 2 bin ½2-4:3 GeV 2 and the position of the zero). The next generation of mea...

In the Standard Model (SM), the rare transitions where a bottom quark decays into a strange quark and a pair of light leptons exhibit a potential sensitivity to physics beyond the SM. In addition, the SM embeds Lepton Flavour Universality (LFU), leading to almost identical probabilities for muon and electron modes. The LHCb collaboration discovered a set of deviations from the SM expectations in decays to muons and also in ratios assessing LFU. Other experiments (Belle, ATLAS, CMS) found consistent measurements, albeit with large error bars. We perform a global fit to all available b → s + − data ( = e, µ) in a model-independent way allowing for different patterns of New Physics. For the first time, the NP hypothesis is preferred over the SM by 5 σ in a general case when NP can enter SM-like operators and their chirally-flipped partners. LFU violation is favoured with respect to LFU at the 3-4 σ level. We discuss the impact of LFU-violating New Physics on the observable P 5 from B → K * µ + µ − and we compare our estimate for long-distance charm contributions with an empirical model recently proposed by a group of LHCb experimentalists. Finally, we discuss NP models able to describe this consistent pattern of deviations.

We discuss the observables for the B → K * (→ Kπ)ℓ + ℓ − decay, focusing on both CP-averaged and CP-violating observables at large and low hadronic recoil with special emphasis on their low sensitivity to form-factor uncertainties. We identify an optimal basis of observables that balances theoretical and experimental advantages, which will guide the New Physics searches in the short term. We discuss some advantages of the observables in the basis, and in particular their improved sensitivity to New Physics compared to other observables. We present predictions within the Standard Model for the observables of interest, integrated over the appropriate bins including lepton mass corrections. Finally, we present bounds on the S-wave contribution to the distribution coming from the B → K * 0 ℓ + ℓ − decay, which will help to establish the systematic error associated to this pollution.

Abstract:We perform a frequentist analysis of q 2 -dependent B → K * (→ Kπ)ℓ + ℓ − angular observables at large recoil, aiming at bridging the gap between current theoretical analyses and the actual experimental measurements. We focus on the most appropriate set of observables to measure and on the role of the q 2 -binning. We highlight the importance of the observables P i exhibiting a limited sensitivity to soft form factors for the search for New Physics contributions. We compute predictions for these binned observables in the Standard Model, and we compare them with their experimental determination extracted from recent LHCb data. Analysing b → s and b → sℓ + ℓ − transitions within four different New Physics scenarios, we identify several New Physics benchmark points which can be discriminated through the measurement of P i observables with a fine q 2 -binning. We emphasise the importance (and risks) of using observables with (un)suppressed dependence on soft form factors for the search of New Physics, which we illustrate by the different size of hadronic uncertainties attached to two related observables (P 1 and S 3 ). We illustrate how the q 2 -dependent angular observables measured in several bins can help to unravel New Physics contributions to B → K * (→ Kπ)ℓ + ℓ − , and show the extraordinary constraining power that the clean observables will have in the near future. We provide semi-numerical expressions for these observables as functions of the relevant Wilson coefficients at the low scale.

We perform a model-independent global fit to b → s + − 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 RK and RK * , respectively. Our analysis, updating Refs. [1,2] and including these new data, suggests the presence of right-handed couplings encoded in the Wilson coefficients C 9 µ and C 10 µ . It also strengthens our earlier observation that a lepton flavour universality violating (LFUV) left-handed lepton coupling (C V 9µ = −C V 10µ ), often preferred from the model building point of view, accommodates the data better if lepton-flavour universal (LFU) NP is allowed, in particular in C U 9 . Furthermore, this scenario with LFU NP provides a simple and model-independent connection to the b → cτ ν anomalies, showing a preference of ≈ 7 σ with respect to the SM. It may also explain why fits to the whole set of b → s + − data or to the subset of LFUV data exhibit stronger preferences for different NP scenarios. Finally, motivated by Z models with vector-like quarks, we propose four new scenarios with LFU and LFUV NP contributions that give a very good fit to data. PACS numbers: 13.25.Hw, 11.30.Hv R [15,19] K * = 1.18 +0.52 −0.32 ± 0.10 . Our treatment for the Belle observables within the global fit follows the same strategy as described in Ref. [1] for arXiv:1903.09578v4 [hep-ph]

Weak radiative decays of the B mesons belong to the most important flavor changing processes that provide constraints on physics at the TeV scale. In the derivation of such constraints, accurate standard model predictions for the inclusive branching ratios play a crucial role. In the current Letter we present an update of these predictions, incorporating all our results for the O(α_{s}^{2}) and lower-order perturbative corrections that have been calculated after 2006. New estimates of nonperturbative effects are taken into account, too. For the CP- and isospin-averaged branching ratios, we find B_{sγ}=(3.36±0.23)×10^{-4} and B_{dγ}=(1.73_{-0.22}^{+0.12})×10^{-5}, for E_{γ}>1.6 GeV. Both results remain in agreement with the current experimental averages. Normalizing their sum to the inclusive semileptonic branching ratio, we obtain R_{γ}≡(B_{sγ}+B_{dγ})/B_{cℓν}=(3.31±0.22)×10^{-3}. A new bound from B_{sγ} on the charged Higgs boson mass in the two-Higgs-doublet-model II reads M_{H^{±}}>480 GeV at 95% C.L.