New results are presented on the reaction π+p→η0Δ++ between 1.2 and 2.67 GeVc. The data above 2 GeVc, when combined with some existing data, give evidence for a dip in the t distribution near t=−1.5 (GeVc).2 This dip, and other features of the data, are adequately described by an A2 Regge-pole model. The effective A2 trajectory is calculated and found to disagree with that obtained from the reaction π−p→η0n.
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New data for the reaction π+p→η0Δ++ are presented at 11 momenta between 1.28 and 2.67 GeV/c. Existing data at higher momenta are included in an analysis of the reaction in terms of A2 exchange. An effective trajectory parametrization of the data above 2 GeV/c is shown to describe adequately those data, although it yields an effective trajectory steeper than expected from ρ−A2 exchange degeneracy. An existing Regge-pole model is refitted to the data above 2 GeV/c with generally satisfactory results. Both the effective trajectory parametrization and the Regge model are extrapolated to the lower-momenta data and shown to give remarkably good agreement with the data. Evidence is presented against a dominant contribution to the lower-momenta data from s-channel resonances.
BACKGROUND SUBTRACTED ONLY ABOVE 1.67 GEV/C.
NOT CORRECTED FOR BACKGROUND - MINIMAL DISTORTION EXPECTED. NORMALIZED TO INTEGRATED CROSS SECTION.
ISOTROPIC FIT JACKSON FRAME DENSITY MATRIX ELEMENTS.
Jet shapes have been measured in inclusive jet production in proton-proton collisions at sqrt(s) = 7 TeV using 3 pb^{-1} of data recorded by the ATLAS experiment at the LHC. Jets are reconstructed using the anti-kt algorithm with transverse momentum 30 GeV < pT < 600 GeV and rapidity in the region |y| < 2.8. The data are corrected for detector effects and compared to several leading-order QCD matrix elements plus parton shower Monte Carlo predictions, including different sets of parameters tuned to model fragmentation processes and underlying event contributions in the final state. The measured jets become narrower with increasing jet transverse momentum and the jet shapes present a moderate jet rapidity dependence. Within QCD, the data test a variety of perturbative and non-perturbative effects. In particular, the data show sensitivity to the details of the parton shower, fragmentation, and underlying event models in the Monte Carlo generators. For an appropriate choice of the parameters used in these models, the data are well described.
Measured Differential Jet Shape RHO as a function of r for jet transverse momentum from 30 to 40 GeV and absolute values of the jet rapidity from 0 to 2.8.
Measured Differential Jet Shape RHO as a function of r for jet transverse momentum from 40 to 60 GeV and absolute values of the jet rapidity from 0 to 2.8.
Measured Differential Jet Shape RHO as a function of r for jet transverse momentum from 60 to 80 GeV and absolute values of the jet rapidity from 0 to 2.8.