Evidence on $qq\bar{q}\bar{q}$ Hadron Spectrum from $\gamma \gamma \to vectormesonvectormeson$ Reactions?

Mitja Rosina, Borut Bajc

The $\gamma \gamma \to {\rho }^0{\rho }^0\to 4\pi$ reaction shows a broad "resonance"at 1.5 GeV with no counterpart in the ${\rho }^{+}{\rho }^{-}$ channel. This $(J^P,J_z)=(2^{+},2)$, $I=0$, and $2$ resonance is considered…