Speaker
Description
This talk will cover the current status and future prospects of experimental searches for light pentaquark states with hadron beams, focusing on both light and hidden-flavor candidates such as $\Theta^+$ and $P_{s\bar{s}}$. Special attention will be given to upcoming experiments at the hadron hall of J-PARC and the KLF at JLab, followed by a highlight of a proposed experiment to study $P_{c\bar{c}}$ states in pion-induced reactions near threshold.
Despite thorough searches using several reaction channels, light pentaquark states remain unobserved. This presentation will revisit the upper limits on the existence of the $\Theta^+$ established by high-statistics CLAS measurements, which rule out earlier claims of positive evidence. In combination with other limits from pion- and kaon-induced reactions, constraints on the $KN\Theta^+$ coupling constants will also be discussed. Accordingly, new experiments are planned to search for the $\Theta^+$ in $K^+p$ and $K^+d$ reactions at J-PARC and in $K^0p$ reactions at JLab.
Searches for hidden-strangeness pentaquarks ($P_{s\bar{s}}$) have been conducted in various reactions, including $\phi$ photoproduction near threshold. Unlike the $\Theta^+$, which is at the apex of the pseudoscalar meson-baryon antidecuplet, the $P_{s\bar{s}}$ states form an isospin doublet within the antidecuplet of vector meson and baryon octets. In addition, $P_s$ states, potentially a $\phi\Lambda$ bound system, will be searched for analogously to the $P_{cs}$ state. This talk discusses experimental prospects at J-PARC, where planned hadron-beam experiments will study $P_{s\bar{s}}$ and $P_s$ states.
The advent of high-momentum hadron beamlines at J-PARC enables new studies of hidden-charm pentaquark states ($P_{c\bar{c}}$), especially via the $\pi^-p\to J/\psi n$ reaction. With a separated $K^-$ beam above 10 GeV$/c$, $P_{c\bar{c}}$ can be investigated through the $K^-p\to J/\psi p K^-$ reaction, which shares its final state with the $\Lambda_b\to J/\psi pK^-$ decay. The $K^+p\to J/\psi p K^+$ reaction provides a cleaner channel for $P_{c\bar{c}}$ studies, free from hyperon resonance complications. This talk will address how these experimental strategies advance our understanding of hidden-charm pentaquarks and the motivation for their study.