Λ[subscript b] → pℓ[superscript -][bar over v]ℓ and Λ[subscript b] → Λ[subscript c]ℓ[superscript -][bar over v]ℓ form factors from lattice QCD with relativistic heavy quarks
Author(s)
Detmold, William; Lehner, Christoph; Meinel, Stefan
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Measurements of the Λ[subscript b] → pℓ[superscript -][bar over v]ℓ and Λ[subscript b] → Λ[subscript c]ℓ[superscript -][bar over v]ℓ decay rates can be used to determine the magnitudes of the Cabibbo-Kobayashi-Maskawa matrix elements V[subscript ub] and V[subscript cb], provided that the relevant hadronic form factors are known. Here we present a precise calculation of these form factors using lattice QCD with 2+1 flavors of dynamical domain-wall fermions. The b and c quarks are implemented with relativistic heavy-quark actions, allowing us to work directly at the physical heavy-quark masses. The lattice computation is performed for six different pion masses and two different lattice spacings, using gauge-field configurations generated by the RBC and UKQCD Collaborations. The b → u and b → c currents are renormalized with a mostly nonperturbative method. We extrapolate the form factor results to the physical pion mass and the continuum limit, parametrizing the q[superscript 2] dependence using z expansions. The form factors are presented in such a way as to enable the correlated propagation of both statistical and systematic uncertainties into derived quantities such as differential decay rates and asymmetries. Using these form factors, we present predictions for the Λ[subscript b] → pℓ[superscript -][bar over v]ℓ and Λ[subscript b] → Λ[subscript c]ℓ[superscript -][bar over v]ℓ differential and integrated decay rates. Combined with experimental data, our results enable determinations of |V[subscript ub]|, |V[subscript cb]|, and |V[subscript ub]/V[subscript cb]| with theory uncertainties of 4.4%, 2.2%, and 4.9%, respectively.
Date issued
2015-08Department
Massachusetts Institute of Technology. Center for Theoretical Physics; Massachusetts Institute of Technology. Department of PhysicsJournal
Physical Review D
Publisher
American Physical Society
Citation
Detmold, William, Christoph Lehner, and Stefan Meinel. "Λ[subscript b] → pℓ[superscript -][bar over v]ℓ and Λ[subscript b] → Λ[subscript c]ℓ[superscript -][bar over v]ℓ form factors from lattice QCD with relativistic heavy quarks." Phys. Rev. D 92, 034503 (August 2015). © 2015 American Physical Society
Version: Final published version
ISSN
1550-7998
1550-2368