Possible $\Sigma({1\over2}^-)$ under the $\Sigma^*(1385)$ peak in $K\Sigma^*$ photoproduction

摘要

The LEPS collaboration has recently reported a measurement of the reaction$\gamma n\to K^+\Sigma^{*-}(1385)$ with linearly polarized photon beam atresonance region. The observed beam asymmetry is sizably negative at$E_\gamma=1.8-2.4 \mathrm{GeV}$, in contrast to the presented theoreticalprediction. In this paper, we calculate this process in the framework of theeffective Lagrangian approach. By including a newly proposed$\Sigma(J^P={1\over2}^-)$ state with mass around 1380~MeV, the experimentaldata for both $\gamma n$ and $\gamma p$ experiments can be well reproduced. Itis found that the $\Sigma({1\over2}^-)$ and/or the contact term may playimportant role and deserve further investigation.