Talk:J/ψ meson

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Is there any alternative spelling without the slash / solidus in the title? It makes the article's location look odd in browser... Ian Cairns 06:11, 29 Sep 2004 (UTC)

No, I don't think so. I actually first tried to use J/Ψ particle as title, but ddn't figure out how to make the Wiki correctly interprete the Ψ instead of displaying the HTML entity. Simon A. 08:23, 29 Sep 2004 (UTC)

The name of the particle is J/ψ, with a small psi. I expanded on the prehistory.--192.35.35.36 23:01, 1 Feb 2005 (UTC)

The name ψ was chosen before they had any spark chamber photographs. The correct story of the name can be found in Crease and Mann The Second Creation.--192.35.35.35 16:45, 3 Feb 2005 (UTC)

A different "J/psi" can be found on the label of some Valdespino sherry: [1] Look down for more instances of the symbol.--192.35.35.35 18:14, 8 Feb 2005 (UTC)

Contents

[edit] the term "charmonium"

I found the therm "charmonium" used as a more general term, not just meaning J/ψ but also ψ and (maybe?) other charm-anticharm mesons (such as ηc or χc). Is that correct? Specifically they used the expression "charmonium spectrum" to reffer to all those different things. If that would be true, maybe the "charmonium" page should be a dissambiguation page or a list of links instead of a plain redirect. --Xavier 01:30, 2005 Apr 3 (UTC)

You are right. (Yes, the term refers to the other ψ's as well. For the non-ψ particles I'm not sure either.) Maybe fix it if you find the time. Simon A. 12:35, 4 Apr 2005 (UTC)

Charmonium is any bound charm-anticharm system. This can be Psi (incl J/Psi), ηc, chi;c and hc
For nomenclature see http://pdg.lbl.gov/2006/reviews/namingrpp.pdf Christoph Scholz 16:04, 9 August 2006 (UTC)
I fixed this by moving it after the paragraph on excited states. TimAdye (talk) 02:28, 25 March 2008 (UTC)

[edit] Infobox

I have updated the infobox, I belive it is not fully filled in though. -Ravedave (help name my baby) 01:28, 5 October 2006 (UTC)

[edit] The "gypsy"!?

I have never heard this informal name. Can anyone supply a reference? (I tagged it with "citation needed".) HEL 00:34, 2 February 2007 (UTC)

[edit] J/psi lifetime

The introduction of the article states: This lifetime was about a thousand times longer than expected. Why is this important? On what physics was the expectation based, and what interesting property of the J/psi gave rise to the longer lifetime? I tagged this with "citation needed" too. (Sorry for being a pest, but it sounds odd otherwise.) HEL 00:42, 2 February 2007 (UTC)

Good point. Not sure, but I think this refers to the GIM mechanism, referred to further down in the article. Charm was needed to make the theoretical estimates of strange particle lifetimes get longer. I'm guessing they didn't get all the mixing angles right at first.

[edit] The Name

I edited the paragraph on the naming of excited states to correct a few inaccuracies. ψ is only used to refer to vector states (orbitally excited states of the J/ψ; ηc and χc are also charm-anticharm bound states, but with different spin-parity). The ψ(3686) is more commonly known as the ψ(2S). I added a reference to the official PDG naming scheme. TimAdye (talk) 02:43, 25 March 2008 (UTC)