Observation of a Narrow Resonance of Mass 2.46 GeV/c^2 in the D_s^*+\pi^0 Final State, and Confirmation of the D_sJ^*(2317)

Abstract

Using 13.5 fb^{-1} of e^+e^- annihilation data collected with the CLEO-II detector, we have observed a new narrow resonance in the D_s^*\pi^0 final state, with a mass near 2.46 GeV/c^2. The search for such a state was motivated by the recent discovery by the BaBar Collaboration of a narrow state at 2.32 GeV/c^2, the D_{sJ}^*(2317)^+, that decays to D_s\pi^0. Reconstructing the D_s\pi^0 and D_s^*\pi^0 final states in CLEO data, we observe a peak in each of the corresponding reconstructed mass difference distributions, \Delta M_{D_s\pi^0} = M(D_s\pi^0) - M(D_s) and \Delta M_{D_s^*\pi^0} = M(D_s^*\pi^0) - M(D_s^*), both of them at values around 350 MeV/c^2. These peaks constitute statistically significant evidence for two distinct states, at 2.32 and 2.46 GeV/c^2, taking into account the background source that each state comprises for the other in light of the nearly identical values of \Delta M observed for the two peaks. We have measured the mean mass differences \Delta M_{D_s\pi^0} = 350.4 \pm 1.2[stat.] \pm 1.0 [syst.] MeV/c^2 for the $D_{sJ}^*(2317)^+$ state, and \Delta M_{D_s^*\pi^0} = 351.6 \pm 1.7[stat.] \pm 1.0 [syst.] MeV/c^2 for the new state at 2.46 GeV/c^2. We have also searched, but find no evidence, for decays of D_{sJ}^*(2317) into the alternate final states D_s^*\gamma, D_s\gamma, and D_s\pi^+\pi^-. The observations of the two states at 2.32 and 2.46 GeV/c^2, in the D_s\pi^0 and D_s^*\pi^0 decay channels respectively, are consistent with their possible interpretations as c s-bar mesons with orbital angular momentum L=1, and spin-parity J^P = 0^+ and 1^+.