Measurement of Masses and Widths of Excited Charm Mesons D * 2 and Evidence for Broad States

Using data from the FOCUS experiment we analyze the D+π− and D0π+ invariant mass distributions. We measure the D∗0 2 mass MD∗0 2 = (2464.5 ± 1.1 ± 1.9)MeV/c2 and width ΓD∗0 2 = (38.7±5.3±2.9)MeV/c2, and theD 2 massMD∗+ 2 = (2467.6± 1.5± 0.76)MeV/c2 and width ΓD∗+ 2 = (34.1± 6.5± 4.2)MeV/c2. We find evidence for broad structures over background in both the neutral and charged final state. If each is interpreted as evidence for a single L = 1, jq = 1/2 excited charm meson resonance, the masses and widths are M0 1/2 = (2407 ± 21 ± 35)MeV/c 2, Γ1/2 = (240 ± 55 ± 59)MeV/c 2, and M 1/2 = (2403 ± 14 ± 35)MeV/c 2 Γ+1/2 = (283 ± 24± 34)MeV/c2, respectively. Interest in charm spectroscopy has shifted from the ground states of (0 and 1) cq̄ mesons to the orbitally and radially excited states. In the limit of infinitely heavy quark mass, the heavy-light meson behaves analogously to the hydrogen atom, i.e., the heavier quark does not contribute to the orbital degrees of freedom (which are completely defined by the light quark). The angular momentum of the heavy quark is described by its spin SQ, and that of the light degrees of freedom are described by jq = sq + L, where sq is the light quark spin and L is the orbital angular momentum of the light quark.