The problem of the X0-meson and its solution

We fitted the X0 production cross-section data using a N* modulation to introduce a rise in the cross-section at lowp *. The fit leads to several solutions, the best one being that having values for the parameters describing the Breit-Wigner resonance(E0,Гel, Г0) = (1889.3, 1.3-0.7+5.8, 1.2-0.9+9.2) MeV. Therefore, one can explain the behaviour of the X0 production cross-section in 7π~p scattering as being due to a narrow N* with mass near 1890 MeV and width ~ 2 MeV.