At CDF we study charged particle production (pT > 0.5 GeV/c, |η| < 0.8) in proton-antiproton collisions at 300 GeV, 900 GeV, and 1.96 TeV. The 300 GeV and 900 GeV data are a result of the “Tevatron... Show moreAt CDF we study charged particle production (pT > 0.5 GeV/c, |η| < 0.8) in proton-antiproton collisions at 300 GeV, 900 GeV, and 1.96 TeV. The 300 GeV and 900 GeV data are a result of the “Tevatron Energy Scan” which was performed just before the Tevatron was shut down. We use the direction of the leading charged particle in each event, PTmax, to define three regions of η-φ space; “toward,” “away,” and “transverse.” The “trans- verse” region is further divided into the “transMAX” and “transMIN” con- tributions. The “transMIN” region is very sensitive to the multiple parton interaction component (MPI) of the “underlying event,” while the “trans-DIF” (“transMAX” minus “transMIN”) is very sensitive to the initial and final-state radiation. This CDF analysis together with LHC data provides a detailed study the energy dependence of the various components of the “underlying event” in hadronic collisions. Show less
