Charged jet cross section and fragmentation in proton-proton collisions at s =7 TeV

Abstract

We report the differential charged jet cross section and jet fragmentation distributions measured with the ALICE detector in proton-proton collisions at a center-of-mass energy $\sqrt{s}=7\text{ }\text{ }\mathrm{TeV}$. Jets with pseudorapidity $|\ensuremath{\eta}|<0.5$ are reconstructed from charged particles using the anti-${k}_{\mathrm{T}}$ jet-finding algorithm with a resolution parameter $R=0.4$. The jet cross section is measured in the transverse momentum interval $5\ensuremath{\le}{p}_{\mathrm{T}}^{\mathrm{ch}\text{ }\mathrm{jet}}<100\text{ }\text{ }\mathrm{GeV}/c$. Jet fragmentation is studied measuring the scaled transverse momentum spectra of the charged constituents of jets in four intervals of jet transverse momentum between 5 and $30\text{ }\text{ }\mathrm{GeV}/c$. The measurements are compared to calculations from the pythia model as well as next-to-leading-order perturbative QCD calculations with powheg+pythia8. The charged jet cross section is well described by powheg for the entire measured range of ${p}_{\mathrm{T}}^{\mathrm{ch}\text{ }\mathrm{jet}}$. For ${p}_{\mathrm{T}}^{\mathrm{ch}\text{ }\mathrm{jet}}>40\text{ }\text{ }\mathrm{GeV}/c$, the pythia calculations also agree with the measured charged jet cross section. pythia6 simulations describe the fragmentation distributions to 15%. Larger discrepancies are observed for pythia8.