S-wave eta'-proton FSI; phenomenological analysis of near-threshold   production of pi0, eta, and eta' mesons in proton-proton collisions
  We describe a novel technique for comparing total cross sections for the reactions pp --> pp pi(0), pp --> pp eta, and pp --> pp eta' close to threshold. The initial and final state proton-proton interactions are factored out of the total cross section, and the dependence of this reduced cross section on the volume of phase space is discussed. Different models of the proton-proton interaction are compared. We argue that the scattering length of the S-wave eta'-proton interaction is of the order of 0.1 fm. 
P. Moskal, H.-H. Adam, J.T. Balewski, A. Budzanowski, J. Budzinski, D.   Grzonka, L. Jarczyk, A. Khoukaz, K. Kilian, P. Kowi...