Measurement of Jet Cross Section and Fragmentation Using Tracks with the ATLAS Detector

Jets are identified and their properties studied using tracks measured by the ATLAS Inner Detector. Events are selected using a minimum-bias trigger, allowing the emergence of jets at low transverse momentum to be observed and for jets to be studied independently of the calorimeter. Jets are reconstructed using the anti-kt algorithm applied to tracks with two parameter choices, 0.4 and 0.6. An inclusive jet transverse momentum cross section measurement from 4 GeV to 80 GeV is shown, integrated over |η | < 0.57 and corrected to charged particle-level truth jets. The probability that a particular particle carries a given fraction of the jet momentum (fragmentation function) is also measured. Comparison with the theoretical models implemented in existing tunings of Monte Carlo event generators with the data indicates reasonable overall agreement between data and Monte Carlo; areas where these tunings could be improved are indicated.