Direct ϱ0 production at large pT

The production of ρ{variant}0 mesons in hadronic interactions is investigated at high transverse momentum (pT > 2 GeV/c). The data come from a sample of π-N interactions at 300 GeV/c obtained at the CERN Omega Spectrometer, requiring at ρ{variant}0→π+π- with pT(pair) > 2 GeV/c to recoil against an opposite particle with pT (opposite) > 1 GeV/c. The signal/(signal + background) ratio of ρ{variant}0 production shows an increase of 38% as ξE = pT (opposite)/pT (pair) decreases from 0.5 <ξE < 1 to ξE ≤ 0.5. This increase is not compatible with a QCD model of parton scattering and subsequent fragmentation, and gives a strong indication that direct ρ{variant}0 production has been observed. Data has now been taken at 150 GeV/c and additional signatures to be used to identify direct ρ{variant}0 production are discussed. © 1989