We report on the status of our calculation of the exclusive semileptonic decay, B → πlv; a key process in the determination of the CKM matrix element |Vub|. The Möbius domain wall action is used for both light and heavy quarks on gauge ensembles that include the effects of 2 + 1 flavours of quarks in the sea at three values of the lattice spacing: a ≈ 0.08 fm, a ≈ 0.055 fm, and a ≈ 0.044 fm. Pion masses go down to 300 MeV while heavy quarks masses are as large as 2.44mc. We present preliminary results of form factors from this process, showing dependence on momentum transfer, lattice spacing, and the heavy quark mass.
$B \to \pi\ell\nu$ form factors and $|V_{ub}|$ with Möbius domain wall fermions
