N3LO calculation of the B to Xs gamma photon spectrum including complete light-fermion corrections, two massive fermion loops, and large-Nc terms, with improved results in kinetic and MSR mass schemes.
QCD-Based Interpretation of the Lepton Spectrum in Inclusive $\bar B\to X_u\,\ell\,\bar\nu$ Decays
2 Pith papers cite this work, alongside 214 external citations. Polarity classification is still indexing.
abstract
We present a QCD-based approach to the endpoint region of the lepton spectrum in $\bar B\to X_u\,\ell\,\bar\nu$ decays. We introduce a genuinely nonperturbative form factor, the shape function, which describes the fall-off of the spectrum close to the endpoint. The moments of this function are related to forward scattering matrix elements of local, higher-dimension operators. We find that nonperturbative effects are dominant over a finite region in the lepton energy spectrum, the width of which is related to the kinetic energy of the $b$-quark inside the $B$ meson. Applications of our method to the extraction of fundamental standard model parameters, among them $V_{ub}$, are discussed in detail.
fields
hep-ph 2years
2026 2verdicts
UNVERDICTED 2representative citing papers
Establishes the HQLaMET two-step factorization scheme to enable lattice QCD computation of the B-meson shape function by separating the effects of disparate scales.
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The photon-energy spectrum in $B\to X_s\gamma$ to N$^3$LO: light-fermion and large-$N_{\rm c}$ corrections
N3LO calculation of the B to Xs gamma photon spectrum including complete light-fermion corrections, two massive fermion loops, and large-Nc terms, with improved results in kinetic and MSR mass schemes.
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Accessing the HQET B-Meson Shape Function from a LaMET Quasi-Shape Function
Establishes the HQLaMET two-step factorization scheme to enable lattice QCD computation of the B-meson shape function by separating the effects of disparate scales.