Speaker
Description
The discoveries of the pentaquark, $P_C$, states and $XYZ$ mesons in the charmed quark sector initiated a new epoch in hadron physics. The existence of exotic multi-quark states beyond the conventional $\textit{q$\overline{q}$}$ and $\textit{qqq}$ systems has obviously been realised. Such states could manifest as single colour bound objects, or evolve from meson-baryon and meson-meson interactions, creating molecular like systems and re-scattering effects near production thresholds.
Intriguingly, similar effects may be evidenced in the light, $uds$ sector. To study a molecular-like and spatially extended baryonic system access to a low momentum exchange and therefore forward meson production region is crucial. The BGOOD photoproduction experiment is uniquely designed to explore this kinematic region; it is comprised of a central calorimeter complemented by a magnetic spectrometer in forward directions.
BGOOD has a rich programme of strangeness photoproduction studies off both proton and neutron (deuterium) target. Recent highlights include a peak-like structure in the $\gamma n \rightarrow K^0\Sigma^0$ cross section at $W\sim2~$GeV consistent with a meson-baryon interaction model which predicted the charmed $P_C$ states. The $K^*\Sigma$ molecular nature of this proposed N*(2030) is also supported in our measurement of $\gamma p \rightarrow K^+\Lambda(1405) (\rightarrow \pi^0\Sigma^0)$, where it is predicted to drive a triangle singularity mechanism.
*Supported by DFG projects 388979758/405882627 and the European Union's Horizon 2020 programme, grant 824093.
