| Popis: |
Using almost 5fb −1 of e+e− data accumulated at the CESR collider in the energy region around 10.5 GeV, the CLEO II collaboration has found evidence for several narrow excitations of the Ξc. Two of these are seen in the modes Ξ c + γ and Ξ c 0 γ are identified with Ξ c 1 , the J p = 1/2 + c{sq} state, which is symmetric under exchange of light quark quantum numbers. The third state is seen in its decay to Ξ c + π+π− via an intermediate Ξ c * and is consistent with the Ξ c1 + , a J p = 3/2− p- wave state analogous to the ⋀ c1 + (2625). The mass differences relative to the ground state are: M(Ξ c + ′) − M(Ξc) = 107.8 ± 1.7 ± 2.5MeV/c2, M(Ξ c 0 ′) − M(Ξc) = 107.0 ± 1.5 ± 2.5MeV/c2, and M(Ξ c + ) − M(Ξ c + ) = 349.4 ± 0.7 ± 1.0MeV/c2 |
