QUASI 2-BODY DECAYS OF CHARM MESONS

Quasi two-body decays of charm mesons are studied by using a hard-meso n approximation in which the amplitude M is given by M similar or equa l to M(ETC) + M(S). The surface term M(S) is given by a sum of all pos sible pole amplitudes involving contributions of four-quark and hybrid mesons in addition to ground-state {<q(q)over bar>}(0) mesons. Contri butions of multihadron intermediate states are taken in the form of M( ETC). The spectator type of decays can have significant contributions of s-channel poles of four-quark mesons. In the annihilation type of d ecays, s-channel hybrid-meson poles can play an important role. The mi xed type of decays can have all the pole contributions of the ground-s tate {<q(q)over bar>}(0), possible hybrid and four-quark mesons in the s-channel. The estimated branching ratios, B(D+ --> (K) over bar(0) r ho(+)) and B(D-0 --> K(-)rho(+)), are of ordinary size, in contrast wi th the factorization which predicts very large rates for these decays. The D-s(+) --> pi(+)omega and D-s(+) --> pi(+)rho(0) decays can be su ppressed in consistency with the other decays.