Joaquim Matias

Global analysis of b → sℓℓ anomalies

A bstractWe 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 → sℓ+ℓ− transitions (ℓ = 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, charm-loop 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 C9NP≃−1

Implications from clean observables for the binned analysis of B → K ∗ μ + μ − at large recoil

{\mathcal{C}}_9^{\mathrm{NP}}\simeq -1

Loop-generated bounds on changes to the graviton dispersion relation

, 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.

Patterns of New Physics in b → sℓ+ℓ− transitions in the light of recent data

A bstractWe 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

Forward-backward and isospin asymmetry for B→K*ℓ+ℓ− decay in the standard model and in supersymmetry

B\to K_0^{*}{\ell^{+}}{\ell^{-}}

Exploring new physics in the C7-C7′ plane

decay, which will help to establish the systematic error associated to this pollution.

Huge right-handed current effects in B → K ∗ (Kπ)ℓ + ℓ − in supersymmetry

A bstractWe perform a frequentist analysis of q2-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 q2-binning. We highlight the importance of the observables Pi 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 Pi observables with a fine q2-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 (P1 and S3). We illustrate how the q2-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.

MSLED: A Minimal supersymmetric large extra dimensions scenario

A bstractThe recent LHCb angular analysis of the exclusive decay B → K*μ+μ− has indicated significant deviations from the Standard Model expectations. Accurate predictions can be achieved at large K*-meson recoil for an optimised set of observables designed to have no sensitivity to hadronic input in the heavy-quark limit at leading order in αs. However, hadronic uncertainties reappear through non-perturbative ΛQCD/mb power corrections, which must be assessed precisely. In the framework of QCD factorisation we present a systematic method to include factorisable power corrections and point out that their impact on angular observables depends on the scheme chosen to define the soft form factors. Associated uncertainties are found to be under control, contrary to earlier claims in the literature. We also discuss the impact of possible non-factorisable power corrections, including an estimate of charm-loop effects. We provide results for angular observables at large recoil for two different sets of inputs for the form factors, spelling out the different sources of theoretical uncertainties. Finally, we comment on a recent proposal to explain the anomaly in B → K*μ+μ− observables through charm-resonance effects, and we propose strategies to test this proposal identifying observables and kinematic regions where either the charm-loop model can be disentangled from New Physics effects or the two options leave different imprints.