Conceptual

Resonant B-to-rho Form Factors from Lattice QCD via Finite-Volume Scattering

The first lattice QCD determination of the B to rho semileptonic vector and axial form factors (V, A0, A1, A12) that treats the rho(770) as an unstable P-wave pi-pi resonance rather than a stable particle. The B to pi-pi finite-volume matrix elements are computed as functions of momentum transfer and dipion invariant mass with the Lellouch-Luscher formalism, then analytically continued to the complex rho pole to extract resonance form factors, providing a route to a precise exclusive determination of the CKM element |Vub|.