K- meson production in the proton-proton reaction at 3.67 GeV/c

The total cross section of the reaction pp --> ppK(+)K(-) has been determined for proton-proton reactions with p(beam) = 3.67 GeV/c. This represents the first cross section measurement of the pp --> ppK(-)K(+) channel near threshold, and is equivalent to the inclusive pp --> ppK(-)X cross section at this beam momentum. The cross section determined at this beam momentum is about a factor 20 lower than that for inclusive pp --> ppK(+)X meson production at the same CM energy above the corresponding threshold. This large difference in the K+ and K- meson inclusive production cross sections in proton-proton reactions is in strong contrast to cross sections measured in sub-threshold heavy ion collisions, which are similar in magnitude at the same energy per nucleon below the respective thresholds.