Inclusive K+ production in proton-proton collisions has been measured at a beam energy of 2.16 GeV using the COSY-ANKE magnetic spectrometer. The resulting spectrum, as well as those corresponding to K+ p and K+ pi+ correlated pairs, can all be well described using consistent values of the total cross sections for the pp->K+ p Lambda, pp->K+ p Sigma0, and pp->K+ n Sigma+ reactions. While the resulting values for Lambda and Sigma0 production are in good agreement with world data, our value for the total Sigma+ production cross section, sigma(pp->K+ n Sigma+) = 2.5+/-0.6(stat)+/-0.4(syst) mkb at an excess energy of epsilon=129 MeV, could only be reconciled with other recently published data if there were a highly unusual near--threshold behaviour.
@article{arxiv.nucl-ex/0703044,
title = {The pp->K+ n Sigma+ reaction near threshold},
author = {Yu. Valdau and V. Koptev and S. Barsov and M. Büscher and S. Dymov and M. Hartmann and A. Kacharava and S. Merzliakov and S. Mikirtychyants and A. Mussgiller and M. Nekipelov and R. Schleichert and H. Ströher and C. Wilkin},
journal= {arXiv preprint arXiv:nucl-ex/0703044},
year = {2008}
}