Measurement of inclusive jet production at sqrt(s) = 2.76 TeV with the CMS detector and calibration of FFTJet algorithm
The double-differential inclusive jet cross section is measured as a function of jet transverse momentum (pT ) and rapidity (y) with pp collision data from the CMS experiment at the LHC. The data were collected in 2013 at 2.76 TeV center-of-mass energy with an integrated luminosity of 5.43 pb−1. Jets are reconstructed with anti-kT algorithm with the scale parameter R = 0.7 and measured over the pT range from 74 to 592 GeV and |y| range from 0 to 3. The reconstructed inclusive jet spectrum is unfolded to the particle-level and compared to the next-to-leading (NLO) order theoretical predictions. Next, a double ratio, (Data/Theory at 2.76 TeV)/(Data/Theory at 8 TeV) is calculated using the inclusive cross section at 8 TeV center-of-mass energy. The results are presented with the experimental and theoretical uncertainties associated with the measurements. The second part of this thesis describes the calibration of the FFTJet algorithm. This is a new approach to jet reconstruction which uses pattern recognition techniques to identify jet-like objects in the energy flow of the event. It allows the user to apply a jet shape model and then reconstruct the jet energies in a subsequent step. In this study, the calibration of this jet reconstruction algorithm is performed for a range of jet scale parameters (R = 0.2 – 1.0) using collision data and simulated samples. The calibration procedure is validated by reconstructing a benchmark process, semi-leptonic tt ̄ decay, and the results are presented.