Comparison of exclusive decay rates for<i>b→u</i>and<i>b→c</i>transitions

Nussinov, S.; Wetzel, Werner

doi:10.1103/physrevd.36.130

Cited by 148 publications

(132 citation statements)

References 10 publications

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“…Thus, the form factors can depend only on the recoil parameter, w. Moreover, at zero recoil (w = 1) the brown muck does not feel any change-it is insensitive to the heavy quark spin and flavor-so that the transition matrix element (with properly normalized initial and final states) is unity. This gives a unique nonperturbative normalization to the form factors [11,29]. By Luke's theorem, this normalization is unchanged at next-to-leading order in the heavy quark expansion [30].…”

Section: Semileptonic Decays a Decays Of The Ground State Heavymentioning

confidence: 99%

Excited heavy baryons and their symmetries III: Phenomenology

et al. 2001

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Phenomenological applications of an effective theory of low-lying excited states of charm and bottom isoscalar baryons are discussed at leading and next-to-leading order in the combined heavy quark and large Nc expansion. The combined expansion is formulated in terms of the counting parameter λ ∼ 1/mQ, 1/Nc; the combined expansion is in powers of λ 1/2 . We work up to next-toleading order. We obtain model-independent predictions for the excitation energies, the semileptonic form factors and electromagnetic decay rates. At leading order in the combined expansion these observables are given in terms of one phenomenological constant which can be determined from the excitation energy of the first excited state of Λc baryon. At next-to-leading order an additional phenomenological constant is required. The spin-averaged mass of the doublet of the first orbitally excited sate of Λ b is predicted to be approximately 5920 M eV . It is shown that in the combined limit at leading and next-to-leading order there is only one independent form factor describing Λ b → Λcℓν; similarly, Λ b → Λ * c ℓν and Λ b → Λc1ℓν decays are described by a single independent form factor. These form factors are calculated at leading and next-to-leading order in the combined expansion. The value of the Λ b → Λcℓν form factor at zero recoil is predicted to be 0.998 at leading order which is very close to HQET value of unity. The electromagnetic decay rates of the first excited states of Λc and Λ b are determined at leading and next-to leading order. The ratio of radiative decay rates Γ(Λ * c → Λcγ)/Γ(Λ b1 → Λ b γ) is predicted to be approximately 0.2, greatly different from the heavy quark effective theory value of unity.

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Section: Semileptonic Decays a Decays Of The Ground State Heavymentioning

confidence: 99%

Excited heavy baryons and their symmetries III: Phenomenology

et al. 2001

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“…The scaling law 2g P * P π m P /f π for the strong D * Dπ coupling constant was first proposed in [7,8]. The splitting between the coplings (1.12) and (1.13) is of order 1/m Q , and therefore has to be taken into account in the chiral computation, to work consistently at the desired order.…”

Section: Introductionmentioning

confidence: 99%

Heavy meson hyperfine splitting: a complete calculation

et al. 1995

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The hyperfine splittingsare analyzed in the framework of an effective lagrangian possessing chiral, heavy flavour and spin symmetries, explicitly broken by a complete set of first order terms. Among these terms, those responsible for the difference between the couplings g P * P * π and g P * P π are evaluated in the QCD sum rules approach. Their contribution to ∆ D and to ∆ B appears to quantitatively balance previously estimated chiral effects nice agreement with the experimental data, solving a suspected puzzle for heavy quark theory.

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“…In order to determine the element V cb of the CabibboKobayashi-Maskawa (CKM) matrix from experimental measurements of these semi-leptonic decays (which are made at ! > 1), it is necessary to know the Isgur-Wise function, and in particular its slope at the zero recoil point, 0 (1). In this letter we report on a lattice QCD calculation of the Isgur-Wise function, and on the corresponding determination of V cb .…”

mentioning

confidence: 99%

“…D and D decays to be parametrized in terms of a single universal function of ! v v 0 , where v and v 0 are the four-velocities of the B and D mesons respectively 1,2]. This function, (!…”

mentioning

confidence: 99%

The Isgur-Wise function from the lattice

et al. 1994

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We calculate the Isgur-Wise function by measuring the elastic scattering amplitude of a D meson in the quenched approximation on a 24 3 48 lattice at = 6:2, using an O(a)-improved fermion action. Fitting the resulting chirally-extrapolated Isgur-Wise function to Stech's relativistic-oscillator parametrization, we obtain a slope parameter 2 = 1:2 + 7 3 . We then use this result, in conjunction with heavy-quark symmetry, to extract V cb from the experimentally measured B ! D l di erential decay width. We nd jV cb j p B =1:48ps = 0:038 + 2 2 + 8 3 , where the rst set of errors is due to experimental uncertainties, while the second is due to the uncertainty in our lattice determination of 2 .Typeset using REVT E X 1

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Comparison of exclusive decay rates forb→uandb→ctransitions

Cited by 148 publications

References 10 publications

Excited heavy baryons and their symmetries III: Phenomenology

Excited heavy baryons and their symmetries III: Phenomenology

Heavy meson hyperfine splitting: a complete calculation

The Isgur-Wise function from the lattice

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