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We provide hadronic input for the B-meson semileptonic transitions to a light pseudoscalar meson at large recoil. The B s → K form factor calculated from QCD lightcone sum rule is updated, to be used for a |V ub | determination from the B s → K ν width. Furthermore, we calculate the hadronic input for the binned observables of B → π + − and B → K + − . In addition to the form factors, the nonlocal hadronic matrix elements are obtained, combining QCD factorization and light-cone sum rules with hadronic dispersion relations. We emphasize that, due to nonlocal effects, the ratio of branching fractions of these decays is not sufficient for an accurate extraction of the |V td /V ts | ratio. Instead, we suggest to determine the Wolfenstein parameters A, ρ, η of the CKM matrix, combining the branching fractions of B → K + − and B → π + − with the direct CP -asymmetry in the latter decay. We also obtain the hadronic matrix elements for a yet unexplored channel B s → K + − .

Section: Jhep08(2017)112 4 Discussionmentioning

confidence: 99%

B s → Kℓν ℓ and B (s) → π(K)ℓ + ℓ − decays at large recoil and CKM matrix elements

Khodjamirian

Rusov

2017

“…The deviations of these quantities from one measure the relative size of the derivative FFs with respect to vector and tensor FFs, 12) where…”

Section: Jhep08(2016)098mentioning

confidence: 99%

“…Here we just summarise the main argument and result. 5 For the B → K * channel at q 2 = 1 GeV 2 the corrections due to twist-4 and αs-correction for {(T1, D ⊥ ), (T0, D0+t)} are {(4, 6), (7,28)}% and { (12,27), (11,31)}% respectively indicating regularity of Di with regard to the twist-and the αs-expansion. Figure 1.…”

Section: Jhep08(2016)098mentioning

confidence: 99%

B →Vℓ+ℓ− in the Standard Model from light-cone sum rules

Bharucha

Straub

Zwicky

2016

Self Cite

538

775

We present B q → ρ, B q → ω, B q → K * , B s → K * and B s → φ form factors from light-cone sum rules (LCSR) at O(α s ) for twist-2 and 3 and O(α 0 s ) for twist-4 with updated hadronic input parameters. Three asymptotic light-cone distribution amplitudes of twist-4 (and 5) are determined, necessary for the form factors to obey the equations of motion. It is argued that the latter constrain the uncertainty of tensor-to-vector form factor ratios thereby improving the prediction of zeros of helicity amplitudes of major importance for B → K * angular observables. We provide easy-to-use fits to the LCSR results, including the full error correlation matrix, in all modes at low q 2 as well as combined fits to LCSR and lattice results covering the entire kinematic range for B q → K * , B s → K * and B s → φ. The error correlation matrix avoids the problem of overestimating the uncertainty in phenomenological applications. Using the new form factors and recent computations of non-factorisable contributions we provide Standard Model predictions for B → K * γ as well as B → K * + − and B s → φµ + µ − at low dilepton invariant mass. Employing our B → (ρ, ω) form factor results we extract the CKM element |V ub | from the semileptonic decays B → (ρ, ω) ν and find good agreement with other exclusive determinations.

“…[49], this branching ratio involves |C + 9 | 2 , and an illustrative back-of-the-envelope computation indicates that for q 2 =8 GeV 2 , one has C + 9 ∼ 0.2 + i1.6 and |C + 9 | 2 ∼ 2.5 for η c + η c = −2.5, whereas C + 9 ∼ 5.6 − i0.6 and |C + 9 | 2 ∼ 32.1 for η c + η c = 1, confirming the expected suppression of B(B + → π + µ + µ − ) with respect to the SM prediction with η c = 1, η c = 0. Also one should take into account when comparing those modes the possible impact of annihilation contributions (see, for instance, [50] for B → K case).…”

Section: Jhep12(2014)125mentioning

confidence: 99%

On the impact of power corrections in the prediction of B → K *μ+μ− observables

Descotes-Genon

Hofer

Matias

et al. 2014

228

242

Abstract:The 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 α s . However, hadronic uncertainties reappear through non-perturbative Λ QCD /m b 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.