Difference between J/Psi and its excited states

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Discussion Overview

The discussion centers on the differences between the J/Psi particle and its excited states within the context of charmonium, focusing on their quantum numbers and naming conventions. Participants explore the implications of these differences in terms of energy and other properties.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant describes the J/Psi state as having quantum numbers J=1, S=1, L=0, with J^{PC} = 1^{--} and questions what changes in excited states J' and J''.
  • Another participant references the Wikipedia page on charmonium, identifying ψ(3686) and ψ(3770) as the excited states with the same JPC = 1--, noting that the first is a radial excitation and the second has L = 2.
  • A participant expresses surprise that radial excitation can occur without changing the particle's name.
  • Another participant comments on the convention of naming particles differently when their energy or properties change, mentioning the use of primes, stars, or numbers to denote differences.

Areas of Agreement / Disagreement

Participants express differing views on the naming conventions and implications of excited states, indicating that there is no consensus on the criteria for naming or the significance of the changes in properties.

Contextual Notes

There are unresolved aspects regarding the definitions of excited states and the criteria for naming conventions, as well as the implications of energy differences on particle classification.

bayners123
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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?
 
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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.
 
I did, thanks! I wasn't aware that radial excitation was possible without changing the name of the particle.
 
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.
 

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