Musings

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 $q q q q\overline{q}$ bound state with an invariant mass of $m_\Phi=1.55 GeV$, and a width, $\Gamma_\Phi=22 MeV$.

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

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

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