Excited Heavy Mesons from Qcd Sum Rules

In this talk, we focus on the L = 1 excited charm mesons. It is heuristic to illustrate them in the following way, although it is not accurate (L is not a conserved quantity). For the ground state (L = 0) mesons which we are familiar with, there are two states with the J quantum numbers: D(0) and D(1). Their difference only lies in the heavy quark spin direction. For the L = 1 case, there are four states: D 0(0 ), D 1(1 ), D1(1 ) and D 2(2 ). In the constituent picture, D 0 contains one heavy quark and one light quark with same spin direction which is opposite to that of the orbital angular momentum. D 1 is the same as D ∗ 0 up to a heavy quark spin flip. D1 is different from D ∗ 0 by the light quark spin flip. And D 2 is the same as D1 except for the heavy quark spin direction.