## Abstract

We present a lattice QCD calculation of form factors for the decay Λ_{b}→pμ^{-}ν_{̄μ}, which is a promising channel for determining the Cabibbo-Kobayashi-Maskawa matrix element |V_{ub}| at the Large Hadron Collider. In this initial study we work in the limit of static b quarks, where the number of independent form factors reduces to two. We use dynamical domain-wall fermions for the light quarks, and perform the calculation at two different lattice spacings and at multiple values of the light-quark masses in a single large volume. Using our form factor results, we calculate the Λ_{b}→pμ ^{-}ν_{̄μ} differential decay rate in the range 14 GeV2≤q2≤qmaxâ¡2, and obtain the integral ∫14 GeV2qmaxâ¡2[dΓ/dq2]dq2/|V_{ub}|2=15.3±4.2 ps^{-}1. Combined with future experimental data, this will give a novel determination of |V_{ub}| with about 15% theoretical uncertainty. The uncertainty is dominated by the use of the static approximation for the b quark, and can be reduced further by performing the lattice calculation with a more sophisticated heavy-quark action.

Original language | English |
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Article number | 014512 |

Journal | Physical Review D - Particles, Fields, Gravitation and Cosmology |

Volume | 88 |

Issue number | 1 |

DOIs | |

State | Published - 23 Jul 2013 |