Extracting vertical bar V{sub ub} vertical bar from B{yields}{pi}l{nu} decays using a multiply-subtracted Omnes dispersion relation

We use a multiply-subtracted Omnes dispersion relation for the form factor f{sup +} in B{yields}{pi} semileptonic decay, allowing the direct input of experimental and theoretical information to constrain its dependence on q{sup 2}, thereby improving the precision of the extracted value of vertical bar V{sub ub} vertical bar. Apart from these inputs we use only unitarity and analyticity properties. We obtain vertical bar V{sub ub} vertical bar=(4.02{+-}0.35)x10{sup -3}, improving the agreement with the value determined from inclusive methods, and competitive in precision with them.