Measurement of angular correlations in Drell-Yan lepton pairs to probe Z/gamma* boson transverse momentum at root s=7 TeV with the ATLAS detector

Abstract
A measurement of angular correlations in Drell-Yan lepton pairs via the phistar observable is presented. This variable probes the same physics as the Z/gamma* boson transverse momentum with a better experimental resolution. The Z/gamma*->e+e- and Z/gamma*->mu+mu- decays produced in proton--proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV are used. The data were collected with the ATLAS detector at the LHC and correspond to an integrated luminosity of 4.6 fb-1. Normalised differential cross sections as a function of phistar are measured separately for electron and muon decay channels. These channels are then combined for improved accuracy. The cross section is also measured double differentially as a function of phistar for three independent bins of the Z boson rapidity. The results are compared to QCD calculations and to predictions from different Monte Carlo event generators. The data are reasonably well described, in all measured Z boson rapidity regions, by resummed QCD predictions combined with fixed-order perturbative QCD calculations. Some of the Monte Carlo event generators are also able to describe the data. The measurement precision is typically better by one order of magnitude than present theoretical uncertainties.
Description
Bibliographic reference
ATLAS Collaboration Cabrera Urbán, Susana Castillo Giménez, María Victoria Costa Mezquita, María José Fassi, Farida Ferrer Soria, Antonio Fiorini, Luca Fuster Verdú, Juan A. García García, Carmen García Navarro, José Enrique González de la Hoz, Santiago Hernández Jiménez, Yesenia Higón Rodríguez, Emilio Irles Quiles, Adrián Kaci, Mohammed Lacasta Llácer, Carlos Lacuesta Miquel, Vicente March, L. Martí García, Salvador Miñano Moya, Mercedes Mitsou, Vasiliki Moles Valls, Regina Moreno Llácer, María Oliver García, Elena Pedraza López, Sebastián Pérez García-Estañ, María Teresa Romero Adam, E. Ros Martínez, Eduardo Salt Cairols, José Sánchez Martínez, V. Soldevila, U. Sánchez, J. Torró Pastor, Emma Valero, A. Valladolid Gallego, E. Valls Ferrer, Juan Antonio Villaplana Pérez, Miguel Vos, Marcel 2013 Measurement of angular correlations in Drell-Yan lepton pairs to probe Z/gamma* boson transverse momentum at root s=7 TeV with the ATLAS detector Physics Letters B 720 1-3 32 51
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