Study Of (P,V)?V Transition Form Factors Within The Standard And Covariant Light-front Quark Models

The form factor of mesonic transition,is an important nonperturbative physical input parameter in phenomenological study of mesonic decays.There are many approaches for evaluating these nonperturbative quantities,for instance,Wirbel-Stech-Bauer model,lattice QCD,QCD sum rules and light-front quark models.The light-front(LF)quark model(QM)includes two methods:standard light-front(SLF)and covariant light-front(CLF),among which SLF QM is simple in concept and convenient in application,and is widely used for the determination of form factor,decay constant and distribution amplitude,as well as the other features of hadrons,while the matrix element evaluated lacks manifest Lorentz covariance and the zero-mode contributions can not be determined explicitly.In order to fill these gaps,CLF QM is proposed to calculate these nonperturbations in a manifest Lorentz covariance approach,meanwhile,the zero-mode contributions can be well determined,but we find that it still has problems such as self-consistency and strict covariance.Aiming at the above two problems and the zero-mode effect,the form factors of(P,V)?V transition are stuied in detail within SLF and CLF in this paper.Through theoretical calculation and numerical analysis,we find that:(i)The problems of consistency and covariance of CLF scheme have a common source.Not all of the light-like vector ??=(0,2,0?)dependencies in the CLF results can be eliminated by the zero-mode contributions,and there are still some residual of ?-dependencies,that are responsible for these problems.(ii)On the basis of the traditional scheme between covariant Bethe-Salpeter approach and LF approach,we add an additional M? M0 substitution,and then find that the CLF self-consistency and covariance problems are solved at the same time.we also find that SLF results are the same as valence contributions of CLF.Finally,we present our numerical predictions for the form factors of c?(q,s)(q=u,d)transitions and b?(q,s,c)transitions induced (P,V)?V decays within a self-consistent scheme,where,many of the decays in V?V are the first to be given.The results of this paper can provide valuable references for the calculation and phenomenological studies of meson decays,and are of great significance for the further understanding of light-front quantization and the improvement of relevant calculation methods.