Speaker
Description
The discoveries of the pentaquark states and $XYZ$ mesons in the charmed quark sector initiated a new epoch in hadron physics, where the existence of exotic multi-quark states beyond the conventional valence three quark and quark-antiquark systems has been confirmed.
Equivalent structures may be evidenced in the light, $uds$ sector, which is the focus of research at the BGOOD photoproduction experiment at the ELSA accelerator in Bonn, Germany. BGOOD is comprised of a central electromagnetic calorimeter and forward spectrometer, enabling access to low momentum exchange kinematics.
Our results in the strangeness sector may suggest a dominant role of meson-baryon dynamics which have an equivalence to the $P_C$ states in the charmed sector. This includes structure in $K^0\Sigma^0$ and $K^+(\Lambda(1405)\rightarrow \pi^0\Sigma^0)$ photoproduction at the $K^*Y$ threshold and a peak at the $K^+K^-p$ threshold in $K^+\Sigma^-$ photoproduction which is only evident at very forward $K^+$ polar angles.
In the non-strange sector, our measurements of the coherent reactions, $\gamma d \rightarrow \pi^0\pi^0 d$, $\gamma d \rightarrow \pi^0\eta d$ and $\gamma d \rightarrow \pi^0\pi^0\pi^0 d$ exhibit forward differential cross sections an order of magnitude higher than phenomenological model calculations.
The INSIGHT experiment, which is an integral part of the Colour meets Flavour excellence cluster is currently being set up at ELSA. The experiment will incorporate high resolution neutral and charged particle detection with an almost complete angular coverage, in combination with a polarised target. It is anticipated that INSIGHT will resolve the nature of the structures observed at BGOOD.