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arXiv · 2212.08833

A lattice QCD study of the $B \to \pi\pi \ell \bar{\nu}$ transition

Luka Leskovec·Stefan Meinel·Marcus Petschlies·John Negele·Srijit Paul·Andrew Pochinsky·Gumaro Rendon
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Abstract

$V_{ub}$ is the smallest and least known of all CKM matrix elements; the community currently determines its magnitude primarily through the exclusive process $B\to\pi\ell\bar{\nu}$. Here we present our progress toward a lattice QCD determination of the $V_{ub}$ matrix element from a novel transition -- $B\to\pi\pi\ell\bar{\nu}$ process, where the $\pi\pi$ system is in a $P$ wave and scattering features the $\rho(770)$ resonance as an enhancement. We perform our calculation on $N_f=2+1$ isotropic clover fermions on a lattice of $L\approx 3.6$ fm and a pion mass of $\approx 320$ MeV; for the $b$-quark we use the anisotropic clover action. After a brief overview of the theoretical framework, we will discuss some preliminary results.

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Luka Leskovec, Stefan Meinel, Marcus Petschlies, John Negele, Srijit Paul, Andrew Pochinsky, Gumaro Rendon. 2022-12-17. A lattice QCD study of the $B \to \pi\pi \ell \bar{\nu}$ transition. https://arxiv.org/abs/2212.08833

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