Lepton-Flavor-Dependent Angular Analysis of B → K * ℓ + ℓ −

A method to directly determine the Wilson coefficients for rare b → s transitions using B 0 → K * 0 µ + µ − decays in an unbinned maximum likelihood fit is presented. The method has several advantages compared to the conventional determination of the Wilson coefficients from angular observables that are determined in bins of q 2 , the square of the mass of the dimuon system. The method uses all experimental information in a more efficient way and automatically accounts for experimental correlations. Performing pseudoexperiments, we show the improved sensitivity of the proposed method for the Wilson coefficients. We also demonstrate that it will be possible to use the method with the combined Run 1 and 2 data sample taken by the LHCb experiment.

Section: Jhep11(2017)176supporting

confidence: 78%

Section: Jhep11(2017)176mentioning

confidence: 99%

See 1 more Smart Citation

Direct determination of Wilson coefficients using B0 → K∗0μ+μ− decays

Hurth

Langenbruch²,

Mahmoudi

2017

“…In other words, the LHCb results point towards a significant effect of the lepton flavor universality violation in this process. Recently, Belle Collaboration [26] found out that the angular observable P 5 agrees with the SM prediction much better for electrons than for muons. This important result suggests that it is much more likely that beyond the SM effects are present in the second generation of leptons, and that there are currently no effects in b → se + e − which would not be accounted for in the SM.…”

mentioning

confidence: 88%

The role of the S 3 GUT leptoquark in flavor universality and collider searches

Doršner

Fajfer

Faroughy

et al. 2017

104

110

Abstract:We investigate the ability of the S 3 scalar leptoquark to address the recent hints of lepton universality violation in B meson decays. The S 3 leptoquark with quantum numbers (3, 3, 1/3) naturally emerges in the context of an SU(5) GUT model without any conflict with the stringent limits from observed nucleon stability. Scalar leptoquark S 3 with left-handed couplings to 2nd and 3rd generations of charged leptons and down-type quarks seems well-suited to address both R K ( * ) and R D ( * ) . We quantify this suitability with numerical fits to a plethora of relevant flavor observables. The proposed SU(5) model calls for a second leptoquark state, i.e.,R 2 with quantum numbers (3, 2, 1/6), if one is to generate gauge coupling unification and neutrino mass. We accordingly include it in our study to investigateR 2 's ability to offset adverse effects of S 3 and thus improve a quality of numerical fits. A global fit of the leptoquark Yukawa couplings shows that large couplings of light S 3 to τ leptons are preferred. We furthermore identify B → K ( * )ν ν as the most sensitive channel to probe the preferred region of parameter space. Large couplings of S 3 to τ leptons are finally confronted with the experimental searches for τ final states at the Large Hadron Collider. These searches comprise a study of decay products of the leptoquark pair production, as well as, and more importantly, an analysis of the high-mass τ τ final states.

“…3 The 'cleanness' of these observables refers to the SM prediction, in the presence of New Physics larger theoretical uncertainties are expected. We didn't include the Q 4 and Q 5 observables measured recently by the Belle collaboration [33].…”

Section: Fitsmentioning

confidence: 99%

Flavour anomalies after the R K ∗ measurement

D’Amico

Nardecchia

Panci

et al. 2017

256

201

The LHCb measurement of the µ/e ratio R K * indicates a deficit with respect to the Standard Model prediction, supporting earlier hints of lepton universality violation observed in the R K ratio. We show that the R K and R K * ratios alone constrain the chiralities of the states contributing to these anomalies, and we find deviations from the Standard Model at the 4σ level. This conclusion is further corroborated by hints from the theoretically challenging b → sµ + µ − distributions. Theoretical interpretations in terms of Z , lepto-quarks, loop mediators, and composite dynamics are discussed. We highlight their distinctive features in terms of the chirality and flavour structures relevant to the observed anomalies.