Measurement of V-cb from the decay process (B)over-bar(0)-> D(*+)l(-)(nu)over-bar

A new precise measurement of \V-cb\ and of the branching ratio BR([(Bover bar](0)→ D(+*)l(-)[([nu]) overbar](l)) has been performed using a sample of about 5000 semileptonic decays(B) overbar (0) → D(*+)l(-)[([nu]) overbar](l), selected by the DELPHI detector at LEP 1 by tagging the soft pion from D*+ → D(0)pi (+). The results are: V-cb = (39.0 +/- 1.5 ( stat.)(- 2.6)(+2.5) (syst. exp.) +/- 1.3(ayst. th.)) x 10(-3). BR((B) overbar0 → D(*+)l(-)[([nu]) overbar](l)) = (4.70 +/- 0.13( stat.)(-0.31)(+0.36) (syst. exp.))%. The analytic dependencies of the differential cross-section and of the Isgur-Wise form factor as functions of the variable w = v(B)0 . v(D)* have also been obtained by unfolding the experimental resolution.