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

Abstract

The LEPS collaboration has recently reported a measurement of the reaction $\gamma n\to K^{+}{\Sigma }^{\ast -}(1385)$ with linearly polarized photon beam at resonance region. The observed beam asymmetry is sizably negative at $E_{\gamma }=1.8-2.4\mathrm{GeV}$, 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 $\Sigma (J^P={\frac{1}{2}}^{-})$ state with mass around 1380~MeV, the experimental data for both $\gamma n$ and $\gamma p$ experiments can be well reproduced. It is found that the $\Sigma ({\frac{1}{2}}^{-})$ and/or the contact term may play important role and deserve further investigation.

Comments: modified version to be published at Phys. Rev. C