Charged jet cross sections and properties in proton-proton collisions at $\sqrt{s}=7$ TeV

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7 TeV
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We present measurements of differential charged jet cross sections, jet fragmentation distributions and jet shapes in minimum bias proton-proton collisions at centre-of-mass energy sqrt{s} = 7 TeV using the ALICE detector at the LHC. Jets are reconstructed from charged particle momenta in the mid-rapidity region using the sequential recombination k_{T} and anti-k_{T} as well as the SISCone jet finding algorithms with several resolution parameters in the range R = 0.2 -- 0.6. Differential jet production cross sections measured with the three jet finders are in mutual agreement in the transverse momentum (p_{T}) range 20 GeV/c < p_{T} < 100 GeV/c. They are also consistent with prior measurements carried out at the LHC by the ATLAS collaboration. We observe that the jet charged particle multiplicity rises monotonically with increasing jet p_{T}, in qualitative agreement with prior observations at lower energies. The transverse profiles of leading jets are investigated using radial momentum density distributions as well as distributions of the average radius containing 80% (R_{80}) of the reconstructed jet p_{T}. We also study the fragmentation of leading jets with R = 0.4 using scaled p_{T} spectra of the jet constituents. Our measurements are compared to model calculations from different event generators (PYTHIA, PHOJET, HERWIG). We find the measured radial density distributions and R_{80} distributions are in good agreement with predictions by the PYTHIA model (tune Perugia-2011). The fragmentation distributions are best described by HERWIG.