Gluon tagging in hard proton-proton interactions at the ISR

Events obtained by triggering on a single particle with high transverse momentump T show a four-jet structure. The two transverse jets are due to the fragmentation of point-like scattered partons. Experimental evidence is presented that highp T K− mesons and their associated jets are produced by hard scattering and subsequent fragmentation of flavour neutral partons with a rather soft structure function. Hence, gluons are a natural source of highp T K− mesons which do not share any valence quark with the incoming protons. The analysis is based upon measurements of short-range quantum number correlations within the trigger jet and of long-range correlations between different jets. The data were obtained at\(\sqrt s\)=62 GeV GeV with the Split Field Magnet Detector (SFM) at the CERN ISR.