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arXiv · 0810.1219

Identification and Rejection of Fake Reconstructed Jets From a Fluctuating Heavy Ion Background in ATLAS

N. Grau·B. A. Cole·W. G. Holzmann·M. Spousta·P. Steinberg
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Abstract

Full jet reconstruction in relativistic heavy ion collisions provides new and unique insights to the physics of parton energy loss. Because of the large underlying event multiplicity in $A+A$ collisions, random and correlated fluctuations in the background can result in the reconstruction of fake jets. These fake jets must be identified and rejected to obtain the purest jet sample possible. A large but reducible fake rate of jets reconstructed using an iterative cone algorithm on HIJING events is observed. The absolute rate of fake jets exceeds the binary-scaled p+p jet rate below 50 GeV and is not negligible until 100 GeV. The variable $Σj_{T}$, the sum of the jet constituent's $E_{T}$ perpendicular to the jet axis, is introduced to identify and reject fake jets at by a factor of 100 making it negligible. This variable is shown to not strongly depend on jet energy profiles modified by energy loss. By studying azimuthal correlations of reconstructed di-jets, the fake jet rate can be evaluated in data.

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N. Grau, B. A. Cole, W. G. Holzmann, M. Spousta, P. Steinberg. 2008-10-07. Identification and Rejection of Fake Reconstructed Jets From a Fluctuating Heavy Ion Background in ATLAS. https://doi.org/10.1140/epjc%2Fs10052-009-0952-z

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