FORM FACTORS FOR B→πlν DECAY IN A MODEL CONSTRAINED BY CHIRAL SYMMETRY AND QUARK MODEL

Abstract

The form factors for the B→π transition are evaluated in the entire momentum transfer range by using the constraints obtained in the framework combining the heavy quark expansion and chiral symmetry for light quarks and the quark model. In particular, we calculate the valence quark contribution and show that it together with the equal time commutator contribution give to the form factors a pole behavior with the heavy (B-meson in our case) mass as the pole mass. This is in addition to the usual vector meson B*-pole diagram for B→πlν in the above framework. We discuss the predictions in our model, which provide an estimate of |Vub|2.