Comment on nonperturbative effects in

Ligeti, Zoltan; Randall, Lisa; Wise, Mark B.

doi:10.1016/s0370-2693(97)00304-3

Cited by 105 publications

(102 citation statements)

References 36 publications

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“…This agrees with the result found in [35][36][37][38] (the correct sign was obtained in the last reference). …”

Section: Analysis Of Thesupporting

confidence: 92%

“…12 GeV 2 [35][36][37][38], which is of the same order in power counting as the perturbative contribution. It is related to charm-penguin diagrams with a soft gluon emission.…”

Section: Review Of Known Results and Preview Of New Onesmentioning

confidence: 87%

“…Previous studies of this effect have focused on its contribution to the total decay rate, which arises from its interference with the matrix element of Q 7γ [35][36][37][38]. In the present work we will generalize this analysis to the case of the photon spectrum in the endpoint region.…”

Section: Introduction and Outlinementioning

confidence: 94%

“…Direct photon contributions can arise from all operator pairings. Some effects involving the conversion of the photon into light partons have been discussed previously in the literature [34][35][36][37][38][39], and it is known (though not widely appreciated) that they fall outside the realm of the local operator product expansion. Let us comment on the various effects one by one:…”

Section: Introduction and Outlinementioning

confidence: 99%

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Factorization at subleading power and irreducible uncertainties in $ \bar{B} \to {X_s}\gamma $ decay

Benzke¹,

Lee²,

Neubert³

et al. 2010

J. High Energ. Phys.

116

162

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Using methods from soft-collinear and heavy-quark effective theory, a systematic factorization analysis is performed for theB → X s γ photon spectrum in the endpoint region m b − 2E γ = O(Λ QCD ). It is proposed that, to all orders in 1/m b , the spectrum obeys a novel factorization formula, which besides terms with the structure H J ⊗ S familiar from inclusiveB → X u lν decay distributions contains "resolved photon" contributions of the form H J ⊗ S ⊗J and H J ⊗ S ⊗J ⊗J. Here S andJ are new soft and jet functions, whose form is derived. These contributions arise whenever the photon couples to light partons instead of coupling directly to the effective weak interaction. The new contributions appear first at order 1/m b and are related to operators other than Q 7γ in the effective weak Hamiltonian. They give rise to non-vanishing 1/m b corrections to the total decay rate, which cannot be described using a local operator product expansion. A systematic analysis of these effects is performed at tree level in hard and hard-collinear interactions. The resulting uncertainty on the decay rate defined with a cut E γ > 1.6 GeV is estimated to be approximately ±5%. It could be reduced by an improved measurement of the isospin asymmetry ∆ 0− to the level of ±4%. We see no possibility to reduce this uncertainty further using reliable theoretical methods.

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“…This agrees with the result found in [35][36][37][38] (the correct sign was obtained in the last reference). …”

Section: Analysis Of Thesupporting

confidence: 92%

“…12 GeV 2 [35][36][37][38], which is of the same order in power counting as the perturbative contribution. It is related to charm-penguin diagrams with a soft gluon emission.…”

Section: Review Of Known Results and Preview Of New Onesmentioning

confidence: 87%

Section: Introduction and Outlinementioning

confidence: 94%

Section: Introduction and Outlinementioning

confidence: 99%

See 2 more Smart Citations

Factorization at subleading power and irreducible uncertainties in $ \bar{B} \to {X_s}\gamma $ decay

Benzke¹,

Lee²,

Neubert³

et al. 2010

J. High Energ. Phys.

116

162

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“…Strictly speaking, these effects are non-local in nature; however, to a good approximation they can be represented by a local 1/m 2 c correction [9,10]. The correct sign of this term has only recently been found in Ref.…”

Section: B → X S γ Branching Ratiomentioning

confidence: 87%

QCD anatomy of $B\to X_s\gamma$ decays

1999

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We present an updated next-to-leading order analysis of the B → X s γ branching ratio and photon spectrum, including consistently the effects of Fermi motion in the heavy-quark expansion. For the Standard Model, we obtain B(B → X s γ) = (2.57 ± 0.26 +0.31 −0.36 ) × 10 −4 for the integral over the high-energy part of the photon spectrum with E lab γ > 2.2 GeV, where the first error reflects the uncertainty in the input parameters, and the second one the uncertainty in the calculation of Fermi motion. This prediction agrees with the CLEO measurement of the same quantity within one standard deviation. From a reanalysis of the CLEO data, we obtain for the total branching ratio B(B → X s γ) = (2.62 ± 0.60 exp +0.37 −0.30 th ) × 10 −4 using the measured rate above 2.2 GeV, and (2.66 ± 0.56 exp +0.43 −0.48 th ) × 10 −4 using a fit to the photon energy spectrum. Both values are consistent with the Standard Model prediction of (3.29 ± 0.33) × 10 −4 . Our analysis contains an improved discussion of renormalization scale dependence and QED corrections. We also study the sensitivity of the branching ratio and photon spectrum to hadronic parameters such as the b-quark mass, and to possible contributions from New Physics beyond the Standard Model.

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Theory of Rare B Decays: b → s γ and b → s ℓ+ ℓ-#8211;

Mannel¹

2004

Heavy Quark Physics

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Comment on nonperturbative effects in

Cited by 105 publications

References 36 publications

Factorization at subleading power and irreducible uncertainties in $ \bar{B} \to {X_s}\gamma $ decay

Factorization at subleading power and irreducible uncertainties in $ \bar{B} \to {X_s}\gamma $ decay

QCD anatomy of $B\to X_s\gamma$ decays

Theory of Rare B Decays: b → s γ and b → s ℓ+ ℓ-#8211;

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