Abstract A strong signal for Double Parton Scattering (DP) is observed in ppbar --> Gamma + 3 jets + X data from the CDF Experiment at the Fermilab Tevatron. The fundamental DP parameter, Sigma_eff, is obtained without reference to theoretical calculations by comparing DP events to events with hard scatterings at separate ppbar collisions. The result, Sigma_eff=(14.5 +/- 1.7 +1.7 -2.3)mb, represents a significant improvement over previous measurements. For the first time, the Feynman x dependence of the Sigma_eff parameter is investigated, and no dependence is seen.

• fig. 1: six_all_three.ps--- Six dist'ns, 1VTX data, with PYTHIA & MIXDP
• fig. 2: ds_1vxt.ps--- dS variable for 1VTX data, with DP signal shown
• fig. 3: six_52_48.ps--- Six dist'ns, 1VTX data, with PYTHIA+MIXDP fits
• fig. 4: 2dataset_dphig1.ps --- 2 Dataset Results for dPhi(Gamma,Jet1) var.
• fig. 5: 2dataset_dphig2.ps --- 2 Dataset Results for dPhi(Gamma,Jet2) var.
• fig. 6: 2dataset_dphig3.ps---2 Dataset Results for dPhi(Gamma,Jet3) var.
• fig. 7: 2dataset_ds.ps--- 2 Dataset Results for dS variable
• fig. 8: construct_results.ps--- Test of 2 Dataset method on "mock data"
• fig. 9: jet_tracking_mult.ps--- Mult. of CTC tracks assoc. w/ jets
• fig. 10: jet_tracking_z_z.ps--- Scatterplot of jet origin matching in z
• fig. 11: ds_2vtx.ps--- dS variable for 2VTX data, for pile-up and DI events
• fig. 12: jet_tracking_ds_2.ps--- dS variable for 2VTX data, 4 Classes
• fig. 13: make_nv_linst.ps--- # VTX verts. per crossing, with Pred'n
• fig. 14: photon_frac_no_et2.ps--- Fraction of true photons in DP & MIXDP
• fig. 15: density_table.ps--- Results of Parton Spatial Density analysis
• fig. 16: x_corr_2x2.ps--- Feynman x dist'ns & correl'ns, DP events
• fig. 17: dynamics_m.ps--- Correlation study, invariant mass
• fig. 18: dynamics_pt.ps--- Correlation study, Pt
• fig. 19: dynamics_pz.ps--- Correlation study, Pz
• fig. 20: mbias_dphi.ps--- Dijet dPhi dist'n, 5 GeV MBias clean dijets
• fig. 21: mbias_eta_phi.ps--- Eta,Phi scatterplot of 5 GeV MBias jets
• fig. 22: mbias_properties.ps--- Properties of 5 GeV MBias jets & dijets

Last updated Feb. 25, 1997