Search for doubly Cabibbo suppressed decays of the charged D meson

The doubly Cabibbo suppressed decayed D{sup +} {yields} K{sup +}{pi}{sup {minus}}{pi}{sup +}, D{sup +} {yields} K{sup +}{pi}{sup 0}and D{sup +} {yields} K*{sup +}{pi}{sup 0} are searched for in a 9.56 pb{sup {minus}1} data sample of e{sup +}e{sup {minus}} annihilation events collected near the {psi}(3770) resonance with the Mark 3 detector at the SPEAR storage ring, at the Stanford Linear Accelerator Center. These rare weak decays are naively expected at a rate of tan{sup 4}{theta}{sub c} relative to corresponding Cabibbo allowed decays. In the context of presently accepted models of hadronic weak decays, however, they are anticipated to be enhanced, making their experimental detection feasible in the Mark 3 data set. The experimentally simplest decay channel D{sup +} {yields} K{sup +}{pi}{sup {minus}}{pi}{sup +} is searched for inclusively through conventional analysis techniques. A signal of approximately 2.5 {sigma} significance is obtained. An independent analysis is performed to establish examples of this decay of D{sup +} {yields} K{sup +}{pi}{sup 0} and K*{sup +}{pi}{sup 0} by full reconstruction of D{sup +}D{sup {minus}} events. Exploiting the two body kinematics of {psi}(3770) {yields} D{bar D}, this second approach obtains significantly smaller backgrounds than the inclusive study. Consistent with the inclusive results, three D{sup +} {yields} K{supmore » +}{pi}{sup {minus}}{pi}{sup +} candidate events are observed. No events are observed for either D{sup +} {yields} K{sup +}{pi}{sup 0} or K*{sup +}{pi}{sup 0}. The branching fraction for D{sup +} {yields} K{sup +}{pi}{sup {minus}}{pi}{sup +} is measured, and limits are established on the branching fractions for D{sup +} {yields} K{sup +}{pi}{sup 0} and K*{sup +}{pi}{sup 0}. These results are used to confront the theoretical predictions from models of the weak hadronic decays of charmed mesons.« less