Subleading-power corrections to the radiative leptonic B → γℓν decay in QCD

et al. 2020

Self Cite

We revisit QCD calculations of radiative heavy meson decay form factors by including the subleading power corrections from the twist-two photon distribution amplitude at next-to-leading-order in α s with the method of the light-cone sum rules (LCSR). The desired hard-collinear factorization formula for the vacuum-to-photon correlation function with the interpolating currents for two heavy mesons is constructed with the operator-product-expansion technique in the presence of evanescent operators. Applying the background field approach, the higher twist corrections from both the two-particle and three-particle photon distribution amplitudes are further computed in the LCSR framework at leading-order in QCD, up to the twist-four accuracy. Combining the leading power "point-like" photon contribution at tree level and the subleading power resolved photon corrections from the newly derived LCSR, we update theory predictions for the nonperturbative couplings describing the electromagnetic decay processes of the heavy mesons H * ± → H ± γ, H * 0 → H 0 γ, H * ± s → H ± s γ (with H = D, B). Furthermore, we perform an exploratory comparisons of our sum rule computations of the heavy-meson magnetic couplings with the previous determinations based upon different QCD approaches and phenomenological models.

Section: Theory Summary For Radiative Heavy Meson Decaysmentioning

confidence: 99%

Section: Theory Summary For Radiative Heavy Meson Decaysmentioning

confidence: 99%

Section: Theory Summary For Radiative Heavy Meson Decaysmentioning

confidence: 99%

Section: Hard-collinear Factorization At Nlo In Qcdmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

QCD calculations of radiative heavy meson decays with subleading power corrections

et al. 2020

Self Cite

QCD calculations of B → π, K form factors with higher-twist corrections

Lü

Shen

et al. 2019

Self Cite

We update QCD calculations of B → π, K form factors at large hadronic recoil by including the subleading-power corrections from the higher-twist B-meson light-cone distribution amplitudes (LCDAs) up to the twist-six accuracy and the strange-quark mass effects at leading-power in Λ/m b from the twist-two B-meson LCDA φ + B (ω, µ). The higher-twist corrections from both the two-particle and three-particle B-meson LCDAs are computed from the light-cone QCD sum rules (LCSR) at tree level. In particular, we construct the local duality model for the twist-five and -six B-meson LCDAs, in agreement with the corresponding asymptotic behaviours at small quark and gluon momenta, employing the QCD sum rules in heavy quark effective theory at leading order in α s . The strange quark mass effects in semileptonic B → K form factors yield the leadingpower contribution in the heavy quark expansion, consistent with the power-counting analysis in soft-collinear effective theory, and they are also computed from the LCSR approach due to the appearance of the rapidity singularities. We demonstrate explicitly that the SU(3)-flavour symmetry breaking effects between B → π and B → K form factors, free of the power suppression in Λ/m b , are suppressed by a factor of α s ( √ m b Λ) in perturbative expansion, and they also respect the large-recoil symmetry relations of the heavy-to-light form factors at least at one-loop accuracy. An exploratory analysis of the obtained sum rules for B → π, K form factors with two distinct models for the B-meson LCDAs indicates that the dominant higher-twist corrections are from the Wandzura-Wilczek part of the two-particle LCDA of twist five g − B (ω, µ) instead of the three-particle B-meson LCDAs. The resulting SU(3)-flavour symmetry violation effects of B → π, K form factors turn out to be insensitive to the non-perturbative models of B-meson LCDAs. We further explore the phenomenological aspects of the semileptonic B → π ν decays and the rare exclusive processes B → Kνν, including the determination of the CKM matrix element |V ub |, the normalized differential q 2 distributions and precision observables defined by the ratios of branching fractions for the above-mentioned two channels in the same intervals of q 2 .

QCD factorization for the four-body leptonic B-meson decays

Wei

2022

Self Cite

Employing the QCD factorization formalism we compute $$ {B}_u^{-}\to {\gamma}^{\ast}\mathrm{\ell}{\overline{v}}_{\mathrm{\ell}} $$ B u − → γ ∗ ℓ v ¯ ℓ form factors with an off-shell photon state possessing the virtuality of order mb ΛQCD and $$ {m}_b^2 $$ m b 2 , respectively, at next-to-leading order in QCD. Perturbative resummation for the enhanced logarithms of mb/ΛQCD in the resulting factorization formulae is subsequently accomplished at next-to-leading logarithmic accuracy with the renormalization-group technique in momentum space. In particular, we derive the soft-collinear factorization formulae for a variety of the subleading power corrections to the exclusive radiative $$ {B}_u^{-}\to {\gamma}^{\ast }{W}^{\ast } $$ B u − → γ ∗ W ∗ form factors with a hard-collinear photon at $$ \mathcal{O}\left({\alpha}_s^0\right) $$ O α s 0 . We further construct a complete set of the angular observables governing the full differential distribution of the four-body leptonic decays $$ {B}_u^{-}\to {\mathrm{\ell}}^{\prime }{\overline{\mathrm{\ell}}}^{\prime}\mathrm{\ell}{\overline{v}}_{\mathrm{\ell}} $$ B u − → ℓ ′ ℓ ¯ ′ ℓ v ¯ ℓ with ℓ, ℓ′ ∈ {e, μ} and then perform an exploratory phenomenological analysis for a number of decay observables accessible at the LHCb and Belle II experiments, with an emphasis on the systematic uncertainties arising from the shape parameters of the leading-twist B-meson light-cone distribution amplitude in heavy quark effective theory.