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Bosch, Stefan W.; Lange, Björn; Neubert, Matthias; Paz, Gil

doi:10.1103/physrevlett.93.221801

Cited by 29 publications

(40 citation statements)

References 16 publications

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“…Cutting on P + samples the same hadronic phase space as a cut on the charged-lepton energy, but with much better efficiency [9,14]. The phase space P + ≤ ∆ P with the ideal separator …”

Section: Cut On Hadronic P +mentioning

confidence: 99%

“…QCD factorization, on the other hand, is better suited for the calculation of partial rates and spectra near kinematical boundaries, where typically some components of P µ X are large, while the invariant hadronic mass M X = P 2 X is small. For example, anyB → X u l −ν event can be described with three independent kinematical variables, a useful choice of which is [9,14] P l = M B − 2E l , P − = E X + | P X | , P + = E X − | P X | .…”

Section: Introductionmentioning

confidence: 99%

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Theory of charmless inclusiveBdecays and the extraction ofVub

2005

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We present "state-of-the-art" theoretical expressions for the triple differentialB → X u l −ν decay rate and for theB → X s γ photon spectrum, which incorporate all known contributions and smoothly interpolate between the "shape-function region" of large hadronic energy and small invariant mass, and the "OPE region" in which all hadronic kinematical variables scale with M B . The differential rates are given in a form which has no explicit reference to the mass of the b quark, avoiding the associated uncertainties. Dependence on m b enters indirectly through the properties of the leading shape function, which can be determined by fitting theB → X s γ photon spectrum. This eliminates the dominant theoretical uncertainties from predictions forB → X u l −ν decay distributions, allowing for a precise determination of |V ub |. In the shape-function region, short-distance and long-distance contributions are factorized at next-to-leading order in renormalization-group improved perturbation theory. Higher-order power corrections include effects from subleading shape functions where they are known. When integrated over sufficiently large portions in phase space, our results reduce to standard OPE expressions up to yet unknown O(α 2 s ) terms. Predictions are presented for partial B → X u l −ν decay rates with various experimental cuts. An elaborate error analysis is performed that contains all significant theoretical uncertainties, including weak annihilation effects. We suggest that the latter can be eliminated by imposing a cut on high lepton invariant mass.

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“…Cutting on P + samples the same hadronic phase space as a cut on the charged-lepton energy, but with much better efficiency [9,14]. The phase space P + ≤ ∆ P with the ideal separator …”

Section: Cut On Hadronic P +mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Theory of charmless inclusiveBdecays and the extraction ofVub

2005

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“…InB → X s γ decays the P + variable is related to the B-meson mass and the photon energy, P + = M B − 2E γ , and the measurement of its spectrum leads directly to the extraction of the leading hadronic structure function, called the shape function [1,2,3]. The P + spectrum in semileptonicB → X u l −ν decays, on the other hand, enables us to determine |V ub | [4,5,6], but this requires a precise knowledge of the shape function. One approach for measuring |V ub | is to first extract the shape function from theB → X s γ photon spectrum, and then to use this information for predictions of event distributions inB → X u l −ν .…”

Section: Introductionmentioning

confidence: 99%

A two-loop relation between inclusive radiative and semileptonicB-decay spectra

Lange¹,

Neubert²,

Paz³

2005

J. High Energy Phys.

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A shape-function independent relation is derived between the partialB → X u l −ν decay rate with a cut on P + = E X − | P X | ≤ ∆ and a weighted integral over the normalizedB → X s γ photon-energy spectrum. The leading-power contribution to the weight function is calculated at next-to-next-to-leading order in renormalization-group improved perturbation theory, including exact two-loop matching corrections at the scale µ i ∼ m b Λ QCD . The overall normalization of the weight function is obtained up to yet unknown corrections of order α 2 s (m b ). Power corrections from phase-space factors are included exactly, while the remaining subleading contributions are included at first order in Λ QCD /m b . At this level unavoidable hadronic uncertainties enter, which are estimated in a conservative way. The combined theoretical accuracy in the extraction of |V ub | is at the level of 5% if a value of ∆ near the charm threshold can be achieved experimentally.

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“…Figure 4 shows q 2 spectra from Belle (left) [18] and Babar (right) [19] of B → X u ℓν candidates where the b → u fraction has been enhanced by requiring low M X . Belle has also displayed candidate events in the variable P + ≡ E X − P X , as recommended in [20], for improved separation from b → cℓν background while minimizing theory uncertainties ( Figure 5(left)). …”

Section: Inclusive B → Uℓν Decaysmentioning

confidence: 99%

Sides of “The” Unitarity Triangle: Results from Belle and Babar

Kinoshita¹

2006

AIP Conference Proceedings

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Abstract. The principal goal of the B-factories is to test the CKM paradigm through measurements that overconstrain the shape of the so-called Unitarity Triangle. The sides of the triangle are evaluated through absolute values of several elements of the CKM matrix, so achieving high precision on these is an important aspect of the B-factory program. Recent results from Belle and Babar are presented.

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Proposal for a Precision Measurement of|Vub|

Cited by 29 publications

References 16 publications

Theory of charmless inclusiveBdecays and the extraction ofVub

Theory of charmless inclusiveBdecays and the extraction ofVub

A two-loop relation between inclusive radiative and semileptonicB-decay spectra

Sides of “The” Unitarity Triangle: Results from Belle and Babar

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