[betatim]

A little history on previous pentaquark discoveries http://link.springer.com/article/10.1140%2Fepjh%2Fe2012-2003...

[jcr]

Unfortunately, that paper is pay-walled by springer.com.

On the bright side, the author of that paper, Kenneth H. Hicks, has provided three different explanations of pentaquarks here:

http://plato.phy.ohiou.edu/~hicks/thplus.html

They are a bit dated due to the news today, but they're helpful.