Eur. Phys. J. C (2009) 61: 785-788
https://doi.org/10.1140/epjc/s10052-009-0955-9

Regular Article - Experimental Physics

Z ⁰-tagged quark jets at the large hadron collider

Physics Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM, 87506, USA

^* e-mail: g.j.kunde@Lanl.gov

Received: 8 October 2008
Revised: 2 February 2009
Published online: 27 February 2009

Abstract

The Large Hadron Collider will allow studies of hard probes in nucleus-nucleus collisions which were not accessible at the Relativistic Heavy Ion Collider—even the study of small cross-section Z ⁰-tagged jets becomes possible. Going beyond the measurement of back-to-back correlations of two strongly interacting particles to measure plasma properties, we replace one side by an electromagnetic probe which propagates through the plasma undisturbed and therefore provides a measurement of the energy of the initial hard scattering. We show that at sufficiently high transverse momentum the Z ⁰-tagged jets originate predominately from the fragmentation of quarks and anti-quarks while gluon jets are suppressed. We propose to use lepton-pair tagged jets to study medium-induced partonic energy loss and to measure in-medium parton fragmentation functions to determine the opacity of the quark gluon plasma.