Analysis of ${\Sigma }^{\ast }$ via isospin selective reaction $K_{L}p\to {\pi }^{+}{\Sigma }^0$

Abstract

The isospin-selective reaction $K_{L}p\to {\pi }^{+}{\Sigma }^0$ provides a clean probe for investigating $I=1$ ${\Sigma }^{\ast }$ resonances. In this work, we perform an analysis of this reaction using an effective Lagrangian approach for the first time, incorporating the well-established $\Sigma (1189)1/2^{+}$, $\Sigma (1385)3/2^{+}$, $\Sigma (1670)3/2^{-}$, $\Sigma (1775)5/2^{-}$ states, while also exploring contributions from other unestablished states. By fitting the available differential cross section and recoil polarization data, adhering to partial-wave phase conventions same as PDG, we find that besides the established resonances, contributions from $\Sigma (1660)1/2^{+}$, $\Sigma (1580)3/2^{-}$ and a ${\Sigma }^{\ast }(1/2^{-})$ improve the description. Notably, a ${\Sigma }^{\ast }(1/2^{-})$ resonance with mass around 1.54 GeV, consistent with $\Sigma (1620)1/2^{-}$, is found to be essential for describing the data in this channel, a stronger indication than found in previous analyses focusing on $\pi \Lambda$ final states. While providing complementary support for $\Sigma (1660)1/2^{+}$ and $\Sigma (1580)3/2^{-}$, our results highlight the importance of the $\Sigma (1620)1/2^{-}$ region in $K_{L}p\to {\pi }^{+}{\Sigma }^0$. Future high-precision measurements are needed to solidify these findings and further constrain the ${\Sigma }^{\ast }$ spectrum.

Comments: 11 pages, 4 figures, 2 tables, accepted by Phys.Rev. D