¦Vub| and constraints on the leading-twist pion distribution amplitude from B → π lv

Using new experimental data on the leptonic mass spectrum of B -> pi lv, we simultaneously determine vertical bar V-ub vertical bar and constrain a(2)(pi) and a(4)(pi), the first two Gegenbauer moments of the pion's leading-twist distribution amplitude. We find vertical bar Vub vertical bar = (3.2 +/- 0.1 +/- 0.1 +/- 0.3) x 10(-3), where the first error is experimental, the second comes from the shape of the form factor in q(2) and the third is a 8% uncertainty from the normalisation of the form factor. We also find a(2)(pi) (1 GeV) = 0. 19 +/- 0. 19 and a(4)(pi) (1 GeV) >= -0.07. (c) 2005 Published by Elsevier B.V.