K$^-$ Meson Production in the Proton-Proton Reaction at 3.67 GeV/c

Abstract 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.