The φp bound state in the unitary coupled-channel approximation

The strong attractive interaction of the phi meson and the proton has recently been reported by the ALICE Collaboration. The corresponding scattering length f(0) is given as Re( f(0)) = 0.85 +/- 0.34(stat)+/- 0.14(syst) and Im(f(0)) = 0.16 +/- 0.10(stat)+/- 0.09(syst) fm. The fact that the real part is significant in contrast to the imaginary part indicates a dominant role of elastic scattering, whereas the inelastic process is less important. In this work, such scattering processes are inspected based on a unitary coupled-channel approach inspired by the Bethe-Salpeter equation. The phi p scattering length is calculated based on this approach, and it is found that the experimental value of the phi p scattering length can be obtained only if the attractive interaction of the phi meson and the proton is taken into account. A significant outcome of such attractive interaction is a two-pole structure in the phi p scattering amplitude. One of the poles, located at (1969 - i283) MeV might correspond to N(1895)1/2(-) or N(1875)3/2(-) as listed in the review of the Particle Data Group (PDG). The other one, located at 1949 - i3 MeV should be a fN bound state, which has no counterpart in the PDG data.

Automated summary

The ALICE Collaboration has recently reported a strong attractive interaction between the phi meson and the proton. The corresponding scattering length f(0) is calculated to be Re( f(0)) = 0.85 +/- 0.34(stat)+/- 0.14(syst) and Im(f(0)) = 0.16 +/- 0.10(stat)+/- 0.09(syst) fm. The dominance of elastic scattering is indicated by the significant real part compared to the imaginary part.