Abstract
An important tool in quark-gluon plasma studies at RHIC has been the measurement of dijets investigated via leading hadron correlations. With much higher rates for hard processes at the Large Hadron Collider, studies of Z0-tagged jets become possible. A clear experimental signature is provided by the measurement of muon pairs from the Z0 decays, for which CMS is an ideally suited detector. Instead of measuring back-to-back correlations of two strongly interacting particles, one side is replaced by an electromagnetic probe which propagates through the plasma undisturbed and provides a measurement of the energy of the initial hard scattering. We propose to use lepton-pair tagged jets to study medium-induced partonic energy loss and to measure in-medium parton fragmentation functions. The lepton pairs from semileptonic decays of heavy meson pairs ([Formula: see text] and [Formula: see text]) are a background source for the tagged dilepton-jet signal. We present the calculated signal rates (using PYTHIA) and background rates (using HVQMNR). We also discuss strategies for maximizing the signal-to-background ratio.
Highlights
Min eraesluarteivmisetnictshpeearvfyorimonedcoaltliRsioHnIsCaitnd√icsaNtNe that a new = 200 GeV state of matter is created 1
In order to estimate the statistical significance of the year one measurement in z = paTssoc/ptTrig, 1000 PYTHIA dimuon triggers were generated with pμTμ > 25 GeV/c
A heavy meson pair can produce a dilepton through DD/BB → l+l− + X, creating a background to the real dilepton signal from Z0 decays
Summary
Min eraesluarteivmisetnictshpeearvfyorimonedcoaltliRsioHnIsCaitnd√icsaNtNe that a new = 200 GeV state of matter is created 1. The challenge and the motivation for the LHC heavy-ion program is to study the properties of this new form of matter. Dijet studies are an important tool for this purpose. Two-hadron angular and transverse momentum correlations probe the back-to-back hard-scattered partons that propagate in the medium before fragmenting 2. We investigate a dijet channel energetically possible, for the first time, at the LHC: high transverse momentum Z0-bosons in association with hadronic jets 3,4. The production channels are qq → Z0g (qq annihilation) and gq → Z0q (Compton scattering) with the subsequent Z0 decay, Z0 → l+l− (l = e, μ), and parton fragmentation, q/g → jet. Because leptons interact weakly with the medium, their reconstructed momentum gives direct access to the initial momentum of the opposite-side jet, making it possible to infer information about the medium from the jet analysis
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