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July 2, 2003

Photoproduction of Exotic Baryons

Interesting news out of Jefferson Lab (better known as the home of CEBAF). There’s a report of the existence of a relatively narrow qqqqq¯q q q q\overline{q} bound state with an invariant mass of m Φ=1.55GeVm_\Phi=1.55 GeV, and a width, Γ Φ=22MeV\Gamma_\Phi=22 MeV.

The experiment collides multi-GeV photons on a deuterium target. The hypothetical exotic is produced in the interaction γnK Φ\gamma n \to K^{-} \Phi. It decays into nK +n K^+, so it has the flavour quantum numbers of dduus¯dduu\overline{s}.

To the untutored eye, the graph looks impressive, and is claimed to be a 5.2σ5.2 \sigma effect. But we’ll have to wait for the PRL

Update (10/8/2003): For more background, see this post.

Posted by distler at July 2, 2003 12:56 PM

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