Role of the possible ${\Sigma }^{\ast }({\frac{1}{2}}^{-})$ state in the $\Lambda p\to \Lambda p{\pi }^0$ reaction

Abstract

The $\Lambda p\to \Lambda p{\pi }^0$ reaction near threshold is studied within an effective Lagrangian method. The production process is described by single-pion and single-kaon exchange. In addition to the role played by the ${\Sigma }^{\ast }(1385)$ resonance of spin-parity $J^P=3/2^{+}$, the effects of a newly proposed ${\Sigma }^{\ast }$ ($J^P=1/2^{-}$) state with mass and width around $1380$ MeV and $120$ MeV are investigated. We show that our model leads to a good description of the experimental data on the total cross section of the $\Lambda p\to \Lambda p{\pi }^0$ reaction by including the contributions from the possible ${\Sigma }^{\ast }({\frac{1}{2}}^{-})$ state. However, the theoretical calculations by considering only the ${\Sigma }^{\ast }(1385)$ resonance fail to reproduce the experimental data, especially for the enhancement close to the reaction threshold. On the other hand, it is found that the single-pion exchange is dominant. Furthermore, we also demonstrate that the angular distributions provide direct information of this reaction, hence could be useful for the investigation of the existence of the ${\Sigma }^{\ast }({\frac{1}{2}}^{-})$ state and may be tested by future experiments.

arXiv comment8 pages, 5 figures

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• S- and p-wave structure of $S=-1$ meson-baryon scattering in the resonance region
• Roles of $a_0(980)$, $\Lambda (1670)$, and $\Sigma (1385)$ in the ${\Lambda }_c^{+}\to \eta \Lambda {\pi }^{+}$ decay
• Photoproduction of ${\Lambda }^{\ast }$ and ${\Sigma }^{\ast }$ resonances with $J^P=1/2^{-}$ off the proton
• $\Lambda (1405)$ production in the process ${\chi }_{c0}(1P)\to \bar{\Lambda }\Sigma \pi$
• New insights into the pole parameters of the $\Lambda (1380)$, the $\Lambda (1405)$ and the $\Sigma (1385)$
• Decay properties of $N^{\ast }(1895)$
• Role of $\Lambda (1670)$ in the $\gamma p\to K^{+}\eta \Lambda$ reaction near threshold
• Role of ${\Sigma }^{\ast }(1/2^{-})$ baryons in ${\Lambda }_c\to \Lambda {\pi }^{+}{\pi }^{+}{\pi }^{-}$ decay
• Exotic properties of N^*(1895) and its impact on photoproduction of light hyperons
• Role of the $\Lambda (1600)$ in the $K^{-}p\to \Lambda {\pi }^0{\pi }^0$ reaction
• Baryon resonances in the strangeness production