Cross sections of the pp→K+Σ+n reaction close to threshold

We have measured inclusive data on K+-meson production in pp collisions at COSY Jülich close to the hyperon production threshold and determined the hyperon-nucleon invariant mass spectra. The spectra were decomposed into three parts: Λp, Σ0p and Σ+n. The cross section for the Σ+n channel was found to be much smaller than a previous measurement in that excess energy region. The data together with previous results at higher energies are compatible with a phase space dependence.