Mechanisms for χcJ→ϕϕ decays

Exclusive decays of χcJ(J=0,2) into ϕϕ are investigated in the framework of perturbative quantum chromodynamics (pQCD) and P03 quark pair creation model. The results show that these two mechanisms exhibit a quite different behavior in evaluating the decay width for the χc0 and χc2. In pQCD method with non-relativistic (NR) approximation, while the calculated χc2→ϕϕ decay width is comparable with measured one, the result for the χc0→ϕϕ decay width is suppressed and much smaller than experimental value. However, in P03 quark pair creation model, the situation is reversed: the decay width of χc0→ϕϕ is greatly enhanced and can reproduce the large measured value, while the contribution to the χc2→ϕϕ decay width is small. The results suggest that while the pQCD mechanism is the dominant mechanism for χc2→ϕϕ decay, the P03 quark pair creation mechanism is the dominant one for χc0→ϕϕ decay.