Are hyperon resonances required in the elementary $K^+\Lambda$ photoproduction?

TL;DR

This study investigates the necessity of hyperon resonances in kaon photoproduction, finding that specific resonances significantly improve model fits and differ from previous assumptions.

Contribution

It demonstrates that the hyperon resonances $ ext{Λ}(1600)P_{01}$ and $ ext{Λ}(1810)P_{01}$ are crucial in modeling $K^+ ext{Λ}$ photoproduction, challenging prior conclusions.

Findings

$ ext{Λ}(1600)P_{01}$ and $ ext{Λ}(1810)P_{01}$ reduce $ ext{χ}^2$ significantly.

Hyperon resonances influence the hadronic form factor cut-off.

Results differ from previous studies emphasizing $ ext{Λ}(1800)S_{01}$.

Abstract

We have investigated the role of hyperon resonances in the kaon photoproduction process, $\gamma p\to K^+\Lambda$, by using a covariant isobar model. To this end, new experimental data are used in the fitting process, whereas the old SAPHIR 1998 data are also used for comparison. The result indicates that the $\Lambda(1600)P_{01}$ and $\Lambda(1810)P_{01}$ hyperon resonances can significantly reduce the $\chi^2$ and, simultaneously, can increase the hadronic form factor cut-off in the background terms. This finding is different from the result of the previous studies, which showed that the $\Lambda(1800)S_{01}$ was important for this purpose, instead of the $\Lambda(1600)P_{01}$.