TY - JOUR

T1 - Underlying event characteristics and their dependence on jet size of charged-particle jet events in pp collisions at (√s)=7  TeV with the ATLAS detector

AU - Barton, Adam

AU - Borissov, Guennadi

AU - Bouhova-Thacker, Eva

AU - Chilingarov, Alexandre

AU - Davidson, Ruth

AU - de Mora, Lee

AU - Dearnaley, William

AU - Fox, Harald

AU - Henderson, Robert

AU - Hughes, Gareth

AU - Jones, Roger William Lewis

AU - Kartvelishvili, Vakhtang

AU - Long, Robin

AU - Love, Peter

AU - Smizanska, Maria

AU - Walder, James

AU - The ATLAS collaboration

N1 - Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. © 2012 CERN, for the ATLAS Collaboration

PY - 2012/10/9

Y1 - 2012/10/9

N2 - Distributions sensitive to the underlying event are studied in events containing one or more charged-particle jets produced in pp collisions at s√=7  TeV with the ATLAS detector at the Large Hadron Collider (LHC). These measurements reflect 800  μb−1 of data taken during 2010. Jets are reconstructed using the anti-kt algorithm with radius parameter R varying between 0.2 and 1.0. Distributions of the charged-particle multiplicity, the scalar sum of the transverse momentum of charged particles, and the average charged-particle pT are measured as functions of pjetT in regions transverse to and opposite the leading jet for 4  GeV<pjetT<100  GeV. In addition, the R dependence of the mean values of these observables is studied. In the transverse region, both the multiplicity and the scalar sum of the transverse momentum at fixed pjetT vary significantly with R, while the average charged-particle transverse momentum has a minimal dependence on R. Predictions from several Monte Carlo tunes have been compared to the data; the predictions from Pythia 6, based on tunes that have been determined using LHC data, show reasonable agreement with the data, including the dependence on R. Comparisons with other generators indicate that additional tuning of soft-QCD parameters is necessary for these generators. The measurements presented here provide a testing ground for further development of the Monte Carlo models.

AB - Distributions sensitive to the underlying event are studied in events containing one or more charged-particle jets produced in pp collisions at s√=7  TeV with the ATLAS detector at the Large Hadron Collider (LHC). These measurements reflect 800  μb−1 of data taken during 2010. Jets are reconstructed using the anti-kt algorithm with radius parameter R varying between 0.2 and 1.0. Distributions of the charged-particle multiplicity, the scalar sum of the transverse momentum of charged particles, and the average charged-particle pT are measured as functions of pjetT in regions transverse to and opposite the leading jet for 4  GeV<pjetT<100  GeV. In addition, the R dependence of the mean values of these observables is studied. In the transverse region, both the multiplicity and the scalar sum of the transverse momentum at fixed pjetT vary significantly with R, while the average charged-particle transverse momentum has a minimal dependence on R. Predictions from several Monte Carlo tunes have been compared to the data; the predictions from Pythia 6, based on tunes that have been determined using LHC data, show reasonable agreement with the data, including the dependence on R. Comparisons with other generators indicate that additional tuning of soft-QCD parameters is necessary for these generators. The measurements presented here provide a testing ground for further development of the Monte Carlo models.

U2 - 10.1103/PhysRevD.86.072004

DO - 10.1103/PhysRevD.86.072004

M3 - Journal article

VL - 86

JO - Physical Review D

JF - Physical Review D

SN - 1550-7998

IS - 7

M1 - 072004

ER -