|Vub| Determination by B → Dsπ

We investigate [Formula: see text] decay in perturbative QCD approach which has recently been applied to B-meson decays. [Formula: see text] decay (and its charge conjugated mode) can be one of the hopeful modes to determine |Vub| since it occurs through b → u transition only. We estimate both factorizable and non-factorizable contribution, and show that the non-factorizable contribution is much less than the factorizable one. Our calculation gives [Formula: see text].