Possible $\hat{I}\pounds ({\frac{1}{2}}^{-})$ under the $\hat{I}{\pounds }^{\ast }(1385)$ peak in $K\hat{I}{\pounds }^{\ast }$ photoproduction

Abstract

The LEPS collaboration has recently reported a measurement of the reaction ${\hat{I}}^{3}n\to K^{+}\hat{I}{\pounds }^{\ast -}(1385)$ with linearly polarized photon beam at resonance region. The observed beam asymmetry is sizably negative at $E_{\hat{I}}^3=1.8-2.4\mathrm{GeV}$, in contrast to the presented theoretical prediction. In this paper, we calculate this process in the framework of the effective Lagrangian approach. By including a newly proposed $\hat{I}\pounds (J^P={\frac{1}{2}}^{-})$ state with mass around 1380~MeV, the experimental data for both ${\hat{I}}^{3}n$ and ${\hat{I}}^{3}p$ experiments can be well reproduced. It is found that the $\hat{I}\pounds ({\frac{1}{2}}^{-})$ and/or the contact term may play important role and deserve further investigation.

modified version to be published at Phys. Rev. C