ηc → VV problem in constituent quark model

The problem about eta(c) decay into two vector mesons, such as eta(c) --> rho rho, K*(K) over bar*, phi phi. are discussed in the Bethe-Salpeter framework. Both constituent quark mass and intrinsic quark transverse motion inside the final state mesons are taken into account and their implications are discussed The result shows that eta(c) --> VLVT is strictly forbidden Quark transverse momentum has apparent effect of enhancing the decay rate. Though both factors are included, the theoretical value is still smaller than the experimental data.