Study of the spectrum of isospin 3/2 Δ⁺⁺(1232) excited states is one of the most important issues in hadronic physics and is attracting much attention because it is the most experimentally accessible system composed of three identical valence quarks. However, our knowledge of these resonances mainly comes from old pN experiments and is still very poor.

Researchers at the Institute of Modern Physics, Chinese Academy of Sciences (IMP) study the Π⁺p->K⁺Σ⁺(1385) and pp->nK⁺Σ⁺(1385) reactions within the effective Lagrangian method by examining the important role of the Δ^*(1940) resonances in these reactions. It is found that the inclusion of the Δ^*(1940) resonance leads to a fairly good description of the low-energy experimental total cross section data of Π⁺p->K⁺Σ⁺(1385) reaction. Based on the study of the pp->nK⁺Σ⁺(1385) reaction, the total and differential cross sections (see Fig. 1) of the Π⁺p->K⁺Σ⁺(1385) reaction are also calculated. It is shown that the new experimental data support the important role played by the Δ^*(1940) resonance with a mass in the region of 1940 MeV and a width of around 200 MeV. The invariant mass distribution and the Dalitz plot provide direct information of the K⁺Σ⁺(1385) production, and they can be tested by future experiments.

The related results have been published in Phys. Rev. C 90, 025207 (2014).

DOI：http://journals.aps.org/prc/abstract/10.1103/PhysRevC.90.025207 

Fig. 1：Angular differential cross sections for the pp->nK⁺Σ⁺(1385) reaction