MODEL FOR CHARMED D-S(+) MESON DECAYS INTO 3 PIONS

We propose a phenomenological three component model describing the dec ay amplitude of the process D-s(+)-->3 pi. The first component is a co nstant background, the second one is a Breit-Wigner amplitude associat ed with a quasi-two-body f(0)(980)pi state, and the third one another Breit-Wipner amplitude corresponding to a possible quasi-two-body rho( 770)pi state. We show that it is possible to reproduce the observed to tal rate for D-s(+)-->pi(+)pi(+)pi(-) as well as the two other measure d branching ratios for the nonresonant part and the resonant f(o) pi() one. The implications of the rho pi(+) state, of which an experiment al limit has been given, are discussed. An upper bound in the 10 MeV r ange for the decay constant f(pi') of the pi(1300) meson is obtained. In our model we assume that inelastic final state strong interactions that may follow the color-suppressed mode D-s--><K(K)over bar>(<(K)ov er bar K>)--3 pi could be neglected. Predictions are given for the D-s (+)-->pi(0) pi(0) pi(+) rate as well as for the pi(+) and pi(-) (pi(0) and pi(+)) energy distributions for these two decay modes D-s(+)-->pi (+)pi(+)pi(-) (D-s(+)-->pi(0) pi(0) pi(+)), respectively.