## Abstract

Motivated by the first search for the rare charged-current B decay to four leptons, ℓν¯ _{ℓ}ℓ^{(′)}ℓ¯ ^{(′)}, we calculate the decay amplitude with factorization methods. We obtain the B→ γ^{∗} form factors, which depend on the invariant masses of the two lepton pairs, at leading power in an expansion in Λ _{QCD}/ m_{b} to next-to-leading order in α_{s}, and at O(αs0) at next-to-leading power. Our calculations predict branching fractions of a few times 10 ^{- 8} in the ℓ^{(′)}ℓ¯ ^{(′)} mass-squared bin up to q2=1GeV^{2} with n+q>3GeV. The branching fraction rapidly drops with increasing q^{2}. An important further motivation for this investigation has been to explore the sensitivity of the decay rate to the inverse moment λ_{B} of the leading-twist B meson light-cone distribution amplitude. We find that in the small-q^{2} bin, the sensitivity to λ_{B} is almost comparable to B^{-}→ ℓ^{-}ν¯ _{ℓ}γ when λ_{B} is small, but with an added uncertainty from the light-meson intermediate resonance contribution. The sensitivity degrades with larger q^{2}.

Original language | English |
---|---|

Article number | 638 |

Journal | European Physical Journal C |

Volume | 81 |

Issue number | 7 |

DOIs | |

State | Published - Jul 2021 |

## Fingerprint

Dive into the research topics of 'QCD factorization of the four-lepton decay B^{-}→ ℓν¯

_{ℓ}ℓ

^{(′)}ℓ¯

^{(′)}'. Together they form a unique fingerprint.