# Charmonium and its decays

1. Apr 14, 2014

### Ichimaru

I'm looking at charmonium and its decays. Given a list of data on the charmonium states I'm asked to say why ψ'' has a leptonic branching ratio a thousand times small than ψ' and J/ψ.

From my understanding this is due to OZI suppression. But I'm having a hard time understanding it intuitively. Why can't any charmonium state annihilate via the strong force to another quark antiquark pair? What is the decay available to the ψ'' that isn't available to ψ' and J/ψ?

Thanks!

2. Apr 14, 2014

### kjhskj75

Isn't it just that the heavier $\psi(3770)$ is heavy enough it can decay rapidly into D mesons that carry away the charm, the lighter ones can't.

See http://pdg8.lbl.gov/rpp2013v2/pdgLive/Particle.action?node=M053 [Broken]

Last edited by a moderator: May 6, 2017
3. Apr 14, 2014

### Einj

Yes, the right answer is that one. The ψ'' is the first charmonium above the open charm threshold and therefore it's much more convenient for it to decay into two D mesons, basically just splitting the two pre-existing charm quarks.