The ρ-meson longitudinal leading-twist distribution amplitude

In the present paper, we suggest a convenient model for the vector ρ  -meson longitudinal leading-twist distribution amplitude ϕ2;ρ‖, whose distribution is controlled by a single parameter B2;ρ‖. By choosing proper chiral current in the correlator, we obtain new light-cone sum rules (LCSR) for the B→ρB→ρ TFFs A1A1, A2A2 and V  , in which the δ1δ1-order ϕ2;ρ‖ provides dominant contributions. Then we make a detailed discussion on the ϕ2;ρ‖ properties via those B→ρB→ρ TFFs. A proper choice of B2;ρ‖ can make all the TFFs agree with the lattice QCD predictions. A prediction of |Vub||Vub| has also been presented by using the extrapolated TFFs, which indicates that a larger B2;ρ‖ leads to a larger |Vub||Vub|. To compare with the BABAR data on |Vub||Vub|, the longitudinal leading-twist DA ϕ2;ρ‖ prefers a doubly-humped behavior.