Λ[subscript b]→Λℓ[superscript +]ℓ[superscript -] form factors and differential branching fraction from lattice QCD

• Main Authors: Detmold, William (Contributor), Lin, C.-J. David (Author), Meinel, Stefan (Contributor), Wingate, Matthew (Author)
• Other Authors: Massachusetts Institute of Technology. Center for Theoretical Physics (Contributor), Massachusetts Institute of Technology. Laboratory for Nuclear Science (Contributor)
• Format: Article
• Language: English
• Published: American Physical Society, 2013-07-12T18:19:19Z.
• Subjects: Article
• Online Access: Get fulltext

 We present the first lattice QCD determination of the Λ[subscript b→]Λ transition form factors that govern the rare baryonic decays Λ[subscript b→]Λℓ[superscript +]ℓ[superscript -] at leading order in heavy-quark effective theory. Our calculations are performed with 2+1 flavors of domain-wall fermions, at two lattice spacings and with pion masses down to 227 MeV. Three-point functions with a wide range of source-sink separations are used to extract the ground-state contributions. The form factors are extrapolated to the physical values of the light-quark masses and to the continuum limit. We use our results to calculate the differential branching fractions for Λ[subscript b→]Λℓ[superscript +]ℓ[superscript -] with ℓ=e, μ, τ within the standard model. We find agreement with a recent CDF measurement of the Λ[subscript b→]Λμ[superscript +]μ[superscript -] differential branching fraction.