HAL: in2p3-00722675, version 1

arXiv: 1208.0563

DOI: 10.1103/PhysRevD.86.072004

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Physical Review D 86 (2012) 072004

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

G. Aad, S. Albrand1, Q. Buat1, B. Clement1, J. Collot1, S. Crépé-Renaudin1, B. Dechenaux1, T. Delemontex1, P.A. Delsart1, M.H. Genest1, J.Y. Hostachy1, E. Laisne1, F. Ledroit-Guillon1, A. Lleres1, A. Lucotte1, F. Malek1, F. Polci1, J. Stark1, X. Sun1, B. Trocmé1, J. Wang1, C. Weydert1, C. Biscarat2, E. Cogneras2, G. Rahal2, S. Abdel Khalek3, H. Abreu3, N. Andari3, C. Arnault3, E. Augé3, P. Barrillon3, M. Benoit3, S. Binet3, C. Bourdarios3, C. de La Taille3, J.B. De Vivie De Regie3, L. Duflot3, M. Escalier3, L. Fayard3, D. Fournier3, J.-F. Grivaz3, S. Henrot-Versillé3, J. Hrivnac3, L. Iconomidou-Fayard3, J. Idarraga3, M. Kado3, N. Lorenzo Martinez3, A. Lounis3, N. Makovec3, P. Matricon3, F. Niedercorn3, L. Poggioli3, P. Puzo3, A. Renaud3, D. Rousseau3, G. Rybkin3, J.B. Sauvan3, J. Schaarschmidt3, A.C. Schaffer3, L. Serin3, S. Simion3, R. Tanaka3, M. Teinturier3, J.J. Veillet3, I. Vukotic3, F. Wicek3, D. Zerwas3, Z. Zhang3, F. Vannucci4, 5, S. Aoun6, C. P. Bee6, C. Bertella6, N. Bousson6, J. C. Clémens6, Y. Coadou6, F. Djama6, F. Etienne6, L. Feligioni6, F. Henry-Couannier6, D. Hoffmann6, F. Hubaut6, E. B. F. G. Knoops6, E. Le Guirriec6, B. Li6, J. Maurer6, E. Monnier6, J. Odier6, P. Pralavorio6, Z. Qian6, A. Rozanov6, M. Talby6, N. Tannoury6, S. Tisserant6, J. Toth6, F. Touchard6, L. Vacavant6, L. Aperio Bella7, B. Aubert7, N. Berger7, J. Colas7, M. Delmastro7, L. Di Ciaccio7, T.K.O. Doan7, S. Elles7, C. Goy7, T. Hryn'Ova7, A. Jérémie7, S. Jézéquel7, M. Kataoka7, J. Labbe7, R. Lafaye7, J. Leveque7, V.P. Lombardo7, N. Massol7, P. Perrodo7, E. Petit7, H. Przysiezniak7, E. Richter-Was7, G. Sauvage7, E. Sauvan7, M. Schwoerer7, T. Todorov7, D. Tsionou7, I. Wingerter-Seez7, R. Zitoun7, D. Boumediene8, E. Busato8, D. Calvet8, S. Calvet8, R. Camacho Toro8, D. Cinca8, J. Donini8, R. Febbraro8, N. Ghodbane8, C. Guicheney8, H. Liao8, D. Pallin8, D. Paredes Hernandez8, F. Podlyski8, C. Santoni8, F. Vazeille8

For the ATLAS collaboration(s)

(2012)

Distributions sensitive to the underlying event are studied in events containing one or more charged-particle jets produced in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector at the Large Hadron Collider (LHC). These measurements reflect 800 inverse microbarns of data taken during 2010. Jets are reconstructed using the antikt 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 pT^JET in regions transverse to and opposite the leading jet for 4 GeV < pT^JET < 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 pT^JET 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.

1:	LPSC - Laboratoire de Physique Subatomique et de Cosmologie
2:	CC IN2P3 - Centre de Calcul de l'inst. national de phy. nucléaire et de phy. des particules
3:	LAL - Laboratoire de l'Accélérateur Linéaire
4:	LPNHE - Laboratoire de Physique Nucléaire et de Hautes Énergies
5:	APC - AstroParticule et Cosmologie
6:	CPPM - Centre de Physique des Particules de Marseille
7:	LAPP - Laboratoire d'Annecy le Vieux de Physique des Particules
8:	LPC-CLERMONT - Laboratoire de Physique Corpusculaire de Clermont-Ferrand

Research team: APC - Neutrinos

Subject(s)

:

Physics/High Energy Physics - Experiment

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From: Emmanuelle Vernay <>

Submitted on: Friday, 3 August 2012 09:21:37

Updated on: Monday, 5 November 2012 16:16:00