20.500.12556/RUL-168786 $B \to \rho \ell \bar{\nu}$ resonance form factors from $B \to \pi \pi \ell \bar{\nu}$ in lattice QCD 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. physics of elementary particles particle interactions lattice QCD form factors fizika osnovnih delcev interakcije delcev kvantna kromodinamika na mreži oblikovni faktorji true false true Angleški jezik Slovenski jezik Članek v reviji 2025-04-24 11:37:47 2025-04-24 11:37:49 2025-04-25 04:12:05 0000-00-00 00:00:00 2025 0 0 Str. 161901-1-161901-8 iss. 16 Vol. 134 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 539.120.811 0031-9007 10.1103/PhysRevLett.134.161901 234136323 PhysRevLett.134.161901.pdf PhysRevLett.134.161901.pdf 1 6E83E1F26A9C8137DC98E82DFA4C50CE 1ad192b79b422499ba6e8b536e6f00e595a9e966219c89a9993ddc4e4d5c30c1 d5fa4aae-20ee-11f0-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=209727 https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.134.161901 0 dc9e5f89-20ee-11f0-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=209728 Fakulteta za matematiko in fiziko 0 0 0