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Form factors for the processes Bc+ →d0ℓ+νℓ and Bc+ → Ds+ ℓ+ℓ- (ν ν ¯) from lattice QCD FORM FACTORS for the PROCESSES Bc+ →d0ℓ+νℓ ⋯ COOPER, DAVIES, and WINGATE

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Peer-reviewed

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Type

Article

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Authors

Cooper, LJ 
Davies, CTH 

Abstract

We present results of the first lattice QCD calculations of the weak matrix elements for the decays Bc+→D0+ν, Bc+→Ds++ and Bc+→Ds+νν. Form factors across the entire physical q2 range are then extracted and extrapolated to the continuum limit with physical quark masses. Results are derived from correlation functions computed on MILC Collaboration gauge configurations with three different lattice spacings and including 2+1+1 flavours of sea quarks in the Highly Improved Staggered Quark (HISQ) formalism. HISQ is also used for all of the valence quarks. The uncertainty on the decay widths from our form factors is similar in size to that from the present value for Vub. We obtain the ratio Γ(Bc+D0μ+νμ)/|ηEWVub|2=4.43(63)×1012 s−1. Combining our form factors with those found previously by HPQCD for Bc+J/ψμ+νμ, we find |Vcb/Vub|2Γ(Bc+→D0μ+νμ)/Γ(Bc+J/ψμ+νμ)=0.257(36)BcD(18)BcJ/ψ. We calculate the differential decay widths of Bc+→Ds++ across the full q2 range, and give integrated results in q2 bins that avoid possible effects from charmonium and uu resonances. For example, we find that the ratio of differential branching fractions integrated over the range q2=1GeV2−6GeV2 for Bc+→Ds+μ+μ and Bc+J/ψμ+νμ is 5.23(73)BcDs(54)BcJ/ψ×10−6. We also give results for the branching fraction of Bc+→Ds+νν. Prospects for reducing our errors in the future are discussed.

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Keywords

hep-lat, hep-lat, hep-ph

Journal Title

Physical Review D

Conference Name

Journal ISSN

2470-0010
2470-0029

Volume Title

105

Publisher

American Physical Society (APS)
Sponsorship
Science and Technology Facilities Council (ST/P000681/1)
Science and Technology Facilities Council (ST/R002452/1)
Science and Technology Facilities Council (ST/R00689X/1)
Science and Technology Facilities Council (ST/M007065/1)
STFC (ST/M007073/1)
STFC (ST/T000694/1)