Speaker
Description
This talk provides an overview of experimental searches for exotic baryon states, such as light pentaquark and hexaquark states, including $\Theta^+$, $P_{s\bar{s}}$, $P_{c\bar{c}}$, and $ H$-dibaryons, utilizing hadron beams. Special attention will be given to upcoming experiments at the hadron hall of J-PARC and the KLF at JLab. The talk will also highlight a proposed experiment to study $P_{c\bar{c}}$ states in pion-induced reactions near threshold.
Despite extensive experimental searches using various reactions, light pentaquark states have not yet been discovered. This talk 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 upper limits from pion- and kaon-induced reactions, constraints on the $KN\Theta^+$ coupling constants will also be discussed. Accordingly, new experiments are being considered 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 pentaquark states ($P_{s\bar{s}}$) have also been conducted in various reactions, including $\phi$ photoproduction near threshold. Unlike the $\Theta^+$, which occupies the apex of the antidecuplet formed by pseudoscalar meson and baryon octet members, the $P_{s\bar{s}}$ states constitute an isospin doublet within the antidecuplet involving vector meson and baryon octet members. Additionally, the $P_{s}$ states, potentially formed by $\phi\Lambda$ or $\phi\Sigma$, will be searched for in analogy to the $P_{cs}$ state. This talk will address the experimental prospects at J-PARC, where a series of experiments is planned to study the $P_{s\bar{s}}$ and $P_s$ states using hadron beams.
The advent of high-momentum hadron beamlines at J-PARC enables new studies of hidden-charm pentaquark states ($P_{c\bar{c}}$), particularly in the $\pi^-p\to J/\psi n$ reaction. The availability of a separated $K^-$ beam above 10 GeV$/c$ creates opportunities to investigate $P_{c\bar{c}}$ states in the $K^-p\to J/\psi p K^-$ reaction, which shares its final state with the $\Lambda_b\to J/\psi pK^-$ decay. Furthermore, the $K^+p\to J/\psi p K^+$ reaction offers a cleaner channel for studying $P_{c\bar{c}}$, as it avoids complications from hyperon resonances. This talk will explore the prospects presented by these new experimental opportunities using hadron beams.
