Read more
The first determination of the strong coupling constant alpha_s via the differential 2-jet-rate in pp collisions at the LHC (at a center-of-mass-energy of 7 TeV) is presented. Data gathered by the ATLAS experiment are fitted by next-to-leading order (NLO) perturbative QCD predictions from calculations with the program NLOJET++. As an observable, the jet-flip-parameter from 3 to 2 reconstructed jets is investigated, using the infrared and collinear safe kT jet algorithm in the exclusive reconstruction mode. The jet-flip-parameters from real data are compared to simulated data from Monte Carlo generators. For the determination of alpha_s, real data have been corrected for the jet-energy-scale, whereas the calculations from NLOJET++ have been corrected for the influence of hadronization effects as well as the impact of the Underlying Event by applying bin-by-bin corrections. The fit between real data and the calculations from NLOJET++ yields a value of alpha_s(M_Z) = 0.120±0.001(stat.)±0.005(syst.), which is in very good agreement with the current world average.
About the author
Dr. rer. nat. Markus Lichtnecker was born in the year 1984. He studied Physics at the Ludwig-Maximilians-Universität in Munich, Germany. After his diploma he did his PhD at the LMU with researches at CERN, Switzerland.
