A Search For The Rare Decay Bsup 0 To Dsub Ssup Rhosup

The authors report on a search for the decay B[sup 0] --> D[sub s][sup +][rho][sup -] in a sample of 90 x 10[sup 6] [Upsilon](4S) decays into B meson pairs collected between 1999 and 2001 with the BABAR detector at the PEP-II asymmetric-energy e[sup +]e[sup -] collider. No significant excess of signal events above the expected background is observed. The authors set a 90% C.L. limit on the branching fraction B(B[sup 0] --> D[sub s][sup +][rho][sup -]) 1.9 x 10[sup -5]. Assuming a flavor SU(3) symmetry relation between the decays B[sup 0] -- D[sub s][sup +][rho][sup -] and B[sup 0] --> D[sup +][rho][sup -], they set a limit on the ratio of CKM-suppressed to CKM-favored amplitudes r(D[rho])