HAL: in2p3-00659804, version 1

arXiv: 1201.2423

DOI: 10.1007/JHEP03(2012)053

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Journal of High Energy Physics 1203 (2012) (2012) 053

Measurement of Event Background Fluctuations for Charged Particle Jet Reconstruction in Pb-Pb collisions at $\sqrt{s_{NN}} = 2.76$ TeV

B. Abelev, N. Arbor1, G. Conesa Balbastre1, J. Faivre1, C. Furget1, R. Guernane1, S. Kox1, Y. Mao1, J.S. Real1, R. Vernet2, L. Aphecetche3, G. Batigne3, M. Bregant3, H. Delagrange3, O. Driga3, M. Estienne3, M. Germain3, A. Lardeux3, F. Lefèvre3, M. Lenhardt3, L. Luquin3, G. Martınez Garcıa3, A. Mas3, A. Matyja3, P. Pillot3, Y. Schutz3, A. Shabetai3, D. Stocco3, I. Belikov4, J.P. Coffin4, Z. Conesa Del Valle4, B. Hippolyte4, S. Jangal4, C. Kuhn4, A. Maire4, A. Michalon4, C. Roy4, X. Sanchez Castro4, S. Senyukov4, R. Wan4, S.U. Ahn5, Y.W. Baek5, A. Baldit5, V. Barret5, N. Bastid5, P. Crochet5, P. Dupieux5, I. Ichou5, X. Lopez5, F. Manso5, M. Marchisone5, S. Porteboeuf-Houssais5, P. Rosnet5, B. Vulpescu5, X. Zhang5, A. Baldisseri6, H. Borel6, J. Castillo Castellanos6, J.L. Charvet6, G. Geuna6, S. Pal6, A. Rakotozafindrabe6, H. Yang6, B. Boyer7, I. Das7, B. Espagnon7, C. Hadjidakis7, I. Hrvnacova7, I. Lajomov7, Y. Le Bornec7, C. Suire7, J.D. Tapia Takaki7, L. Valencia Palomo7, c. Cheshkov8, B. Cheynis8, L. Ducroux8, J.-Y. Grossiord8, M. Guilbaud8, L. Massacrier8, R. Tieulent8, A. Uras8

For the ALICE collaboration(s)

(2012)

The effect of event background fluctuations on charged particle jet reconstruction in Pb-Pb collisions at sqrt(s_NN) = 2.76 TeV has been measured with the ALICE experiment. The main sources of non-statistical fluctuations are characterized based purely on experimental data with an unbiased method, as well as by using single high p_t particles and simulated jets embedded into real Pb-Pb events and reconstructed with the anti-kt jet finder. The influence of a low transverse momentum cut-off on particles used in the jet reconstruction is quantified by varying the minimum track p_t between 0.15 GeV/c and 2 GeV/c. For embedded jets reconstructed from charged particles with p_t > 0.15 GeV/c, the uncertainty in the reconstructed jet transverse momentum due to the heavy-ion background is measured to be 11.3 GeV/c (standard deviation) for the 10% most central Pb-Pb collisions, slightly larger than the value of 11.0 GeV/c measured using the unbiased method. For a higher particle transverse momentum threshold of 2 GeV/c, which will generate a stronger bias towards hard fragmentation in the jet finding process, the standard deviation of the fluctuations in the reconstructed jet transverse momentum is reduced to 4.8-5.0 GeV/c for the 10% most central events. A non-Gaussian tail of the momentum uncertainty is observed and its impact on the reconstructed jet spectrum is evaluated for varying particle momentum thresholds, by folding the measured fluctuations with steeply falling spectra.

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:	SUBATECH - Laboratoire SUBATECH Nantes
4:	IPHC - Institut Pluridisciplinaire Hubert Curien
5:	LPC-CLERMONT - Laboratoire de Physique Corpusculaire de Clermont-Ferrand
6:	IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers (ex DAPNIA)
7:	IPNO - Institut de Physique Nucléaire d'Orsay
8:	IPNL - Institut de Physique Nucléaire de Lyon

Research team: Alice

Subject(s)

:

Physics/High Energy Physics - Experiment

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From: Emmanuelle Vernay <>

Submitted on: Friday, 13 January 2012 16:30:36

Updated on: Friday, 25 January 2013 07:26:30