# Difference between J/Psi and its excited states

1. May 20, 2013

### bayners123

The J/Psi is a state of charmonium with J=1, S=1, L=0. So $J^{PC} = 1^{--}$.
It can be excited to states $J^\prime \textrm{ and } J^{\prime\prime}$, but these don't change any of these numbers. So what is changing?

2. May 20, 2013

### Bill_K

The "charmonium" page in Wikipedia has a full list of the charmonium states and their quantum numbers. By J' and J'' do you mean ψ(3686) and ψ(3770)? These are the lowest lying states with JPC = 1--. Looks like the first one is a radial excitation, n = 2, and the second one has L = 2.

3. May 23, 2013

### bayners123

I did, thanks! I wasn't aware that radial excitation was possible without changing the name of the particle.

4. May 23, 2013

### Staff: Mentor

If the energy (or any other particle property) is different, the particle has a different name - sometimes, it is just an additional prime, a star or a number (denoting the approximate mass), but the name is different.