Observation of a narrow resonance of mass 2.46 GeV/c2 decaying to D*+sπ0 and confirmation of the D*sJ(2317) state

Using 13.5 fb^-1 of e⁺e^- annihilation data collected with the CLEO II detector, we have observed a narrow resonance decaying to D_s^*+π⁰ with a mass near 2.46GeV/c². The search for such a state was motivated by the recent discovery by the BaBar Collaboration of a narrow state at 2.32GeV/c², the D_sJ^*(2317)⁺, that decays to D_s⁺π⁰. Reconstructing the D_s⁺π⁰ and D_s^*+π⁰ final states in CLEO data, we observe peaks in both of the corresponding reconstructed mass difference distributions, ΔM(D_sπ⁰)=M(D_sπ⁰)-M(D_s) and ΔM(D_s^*π⁰)=M(D_s^*π⁰)-M(D_s^*), both of them at values near 350MeV/c². We interpret these peaks as signatures of two distinct states, the D_sJ^*(2317)⁺ plus a new state, designated as the D_sJ(2463)⁺. Because of the similar ΔM values, each of these states represents a source of background for the other if photons are lost, ignored or added. A quantitative accounting of these reflections confirms that both states exist. We have measured the mean mass differences <ΔM(D_sπ⁰)>=350.0±1.2(stat)±1.0(syst)MeV/c² for the D_sJ^*(2317)⁺ state, and <ΔM(D_s^*π⁰)>=351.2±1.7(stat)±1.0(syst)MeV/c² for the new D_sJ(2463)⁺ state. We have also searched, but find no evidence, for decays of the two states via the channels D_s^*+γ,D_s⁺γ, and D_s⁺π⁺π^-. The observations of the two states at 2.32 and 2.46GeV/c², in the D_s⁺π⁰ and D_s^*+π⁰ decay channels, respectively, are consistent with their interpretations as cs¯ mesons with an orbital angular momentum L=1 and spin and parity J^P=0⁺ and 1⁺.