Hadronic D Decays Involving Scalar Mesons

The nonleptonic weak decays of charmed mesons into a scalar meson and a pseudoscalar meson are studied. The scalar mesons under consideration are σ [or f0(600)], κ, f0(980), a0(980) and K 0 (1430). A consistent picture provided by the data suggests that the light scalars below or near 1 GeV form an SU(3) flavor nonet and are predominately the q2q̄2 states, while the scalar mesons above 1 GeV can be described as a qq̄ nonet. Hence, we designate q2q̄2 to σ, κ, a0(980), f0(980) and qq̄ to K 0 . Sizable weak annihilation contributions induced from final-state interactions are essential for understanding the data. Except for the Cabibbo doubly suppressed channel D+ → f0K, the data of D → σπ, f0π, f0K, K 0π can be accommodated in the generalized factorization approach. However, the predicted rates for D → a0π, a0K are too small by one to two orders of magnitude when compared with the preliminary measurements. Whether or not one can differentiate between the two-quark and four-quark pictures for the f0(980) produced in the hadronic charm decays depends on the isoscalar f0−σ mixing angle in the qq̄ model.