Improved unitarity bounds for (B)over-bar-(0)->pi(+)l(-)(nu)over-bar-(l) decays

We obtain model independent bounds for the form factors which arise in semi leptonic B --> pi decays. To this end we derive a theoretical restriction f or possible combinations of the value of the form factor and its derivative s at the end point region, These restrictions are then used as an input in a - slightly modified - general formalism, which has already been deduced a nd applied in earlier publications. Our results can be used to set constrai nts on the form factors which have to be obeyed by all model dependent para metrizations, (C) 1998 Elsevier Science B.V.