TY  - JOUR
T1  - Measurement of event shapes at large momentum transfer with the ATLAS detector in pp collisions at √s=7 TeV
JF  - The European Physical Journal C
N2  - A measurement of event shape variables is presented for large momentum transfer proton-proton collisions using the ATLAS detector at the Large Hadron Collider. Six event shape variables calculated using hadronic jets are studied in inclusive multi-jet events in 35 pb\(^{−1}\) of integrated luminosity at a center-of-mass energy of √s=7 TeV. These measurements are compared to predictions by three Monte Carlo event generators containing leading-logarithmic parton showers matched to leading order matrix elements for 2→2 and 2→n (n=2,…,6) scattering. Measurements of the third-jet resolution parameter, aplanarity, thrust, sphericity, and transverse sphericity are generally well described. The mean value of each event shape variable is evaluated as a function of the average momentum of the two leading jets p\(_{T,1}\) and p\(_{T,2}\), with a mean p\(_T\) approaching 1 TeV.
KW  - JES uncertainty
KW  - event shape variable
KW  - jet energy scale
KW  - event shape observable
KW  - jet cross section
KW  - high jet multiplicity
KW  - jet calibration
KW  - parton shower
KW  - energy scale
KW  - MC program
KW  - hadronic final state
KW  - jet transverse momentum
KW  - MC event generator
KW  - systematic uncertainty
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-127813
VL  - 72
IS  - 2211
ER  - 
TY  - JOUR
T1  - Measurement of \(t\overline t\) production with a veto on additional central jet activity in pp collisions at √s=7 TeV using the ATLAS detector
JF  - European Physical Journal C
N2  - A measurement of the jet activity in \(t\overline t\) events produced in proton–proton collisions at a centre-of-mass energy of 7 TeV is presented, using 2.05 fb\(^{−1}\) of integrated luminosity collected by the ATLAS detector at the Large Hadron Collider. The \(t\overline t\) events are selected in the dilepton decay channel with two identified b-jets from the top quark decays. Events are vetoed if they contain an additional jet with transverse momentum above a threshold in a central rapidity interval. The fraction of events surviving the jet veto is presented as a function of this threshold for four different central rapidity interval definitions. An alternate measurement is also performed, in which events are vetoed if the scalar transverse momentum sum of the additional jets in each rapidity interval is above a threshold. In both measurements, the data are corrected for detector effects and compared to the theoretical models implemented in MC@NLO, Powheg, Alpgen and Sherpa. The experimental uncertainties are often smaller than the spread of theoretical predictions, allowing deviations between data and theory to be observed in some regions of phase space.
KW  - jet reconstruction efficiency
KW  - jet energy scale
KW  - jet energy scale uncertainty
KW  - fiducial cross section
KW  - individual systematic uncertainty
KW  - jet energy resolution
KW  - systematic uncertainty
KW  - muon reconstruction efficiency
KW  - rapidity interval
KW  - pythia parton shower
KW  - jet transverse momentum
KW  - underlying event tune
KW  - particle level jet
KW  - additional jet
KW  - MC event generator
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-128931
VL  - 72
IS  - 2043
ER  -