Mesonic Form Factors in the Light-Front Quark Model
  Form factors for $P\to P$ and $P\to V$ transitions due to the valence-quark configuration are calculated directly in the physical time-like range of momentum transfer within the light-front quark model. It is pointed out that the Bauer-Stech-Wirbel type of light-front wave function fails to give a correct normalization for the Isgur-Wise function at zero recoil in $P\to V$ transition. Some of the $P\to V$ form factors are found to depend on the recoiling direction of the daughter mesons relative to their parents. Thus, the inclusion of the non-valence contribution arising from quark-pair creation is mandatory in order to ensure that the physical form factors are independent of the recoiling direction. 
Hai-Yang Cheng