Padé approximants to B →πℓνℓ and Bs →kℓνℓ and determination of |Vub |

Sergi Gonzàlez-Solís, Pere Masjuan, Camilo Rojas

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12 Citations (Scopus)


In light of the first observation of the semileptonic decay Bs0→K-μ+νμ by the LHCb Collaboration, we revisit the determination of the Cabibbo-Kobayashi-Maskawa parameter |Vub| from exclusive semileptonic B-meson decays. A controlled theoretical input on the Standard Model B→π and Bs→K vector and scalar form factors from Lattice QCD in the large q2 region, in combination with experimental measurements of the differential B→πℓνℓ and Bs0→K-μ+νμ branching ratio distributions, has allowed us determine |Vub|=3.86(11)×10-3 and |Vub|=3.58(9)×10-3 from the analyses of the individual decay channels, respectively, and |Vub|=3.68(5)×10-3 from a simultaneous analysis of both decays, which is only a 1.4% error and differs by 1.8σ with respect to the value from inclusive determinations |Vub|=4.25(12)-14+15(23)×10-3. Our results are based on the use of Padé approximants to the participating form factors, highlighting the importance of the decay Bs→Kμνμ in complementing the traditional B→πℓνℓ one in the exclusive determination of |Vub| and allowing us to obtain, to the best of our knowledge, the first correlated results for the B→π and Bs→K vector and scalar form factors. We hope that our study strengthens the case for precise measurements of the differential Bs→Kℓνℓ decay rate with a finer resolution of the q2 bins, as it would definitely allow achieving more conclusive results for |Vub|.

Original languageEnglish
Article number114041
Number of pages16
JournalPhysical Review D
Issue number11
Publication statusPublished - 1 Dec 2021


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