$B to rho ell bar{nu}$ resonance form factors from $B to pi pi ell bar{nu}$ in lattice QCD
Year: 2025
Type: article
Abstract: The decay $B to rho ell bar{nu}$ is an attractive process for determining the magnitude of the smallest Cabibbo-Kobayashi-Maskawa matrix element, $|V_{ub}|$, and can provide new insights into the origin of the longstanding exclusive-inclusive discrepancy in determinations of this standard-model parameter. This requires a nonperturbative QCD calculation of the $B to rho$ form factors $V$, $A_0$, $A_1$, and $A_{12}$. The unstable nature of the $rho$ resonance has prevented precise lattice QCD calculations of these form factors to date. Here, we present the first lattice QCD calculation of the $B to rho$ form factors in which the $rho$ is treated properly as a resonance in $P$-wave $pi pi$ scattering. To this end, we use the Lellouch-Lüscher finite-volume formalism to compute the $B to pi pi$ form factors as a function of both momentum transfer and $pi pi$ invariant mass, and then analytically continue to the $rho$ resonance pole. This calculation is performed with 2 + 1 dynamical quark flavors at a pion mass of approximately 320 MeV, and demonstrates a clear path toward results at the physical point.
Authors: Leskovec, Luka, Meinel, Stefan, Petschlies, Marcus, Negele, John W., Paul, Srijit, Pochinsky, Andrew
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7045932682
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