Using Z boson events to study parton-medium interactions in Pb-Pb collisions
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Type :
Article
Publication Status :
Published
Access :
Attribution 4.0 International
openAccess
http://creativecommons.org/licenses/by/4.0/
openAccess
http://creativecommons.org/licenses/by/4.0/
Abstract
The spectra measurements of charged hadrons produced in the shower of a parton originating in the same hard scattering with a leptonically decaying Z boson are reported in lead-lead nuclei (Pb-Pb) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. Both Pb-Pb and pp data sets are recorded by the CMS experiment at the LHC and correspond to an integrated luminosity of 1.7 nb-1 and 320 pb-1, respectively. Hadronic collision data with one reconstructed Z boson candidate with the transverse momentum pT>30 GeV/c are analyzed. The Z boson constrains the initial energy and direction of the associated parton. In heavy ion events, azimuthal angular distributions of charged hadrons with respect to the direction of a Z boson are sensitive to modifications of the in-medium parton shower and medium response. compared to reference data from pp interactions, the results for central Pb-Pb collisions indicate a modification of the angular correlations. The measurements of the fragmentation functions and pT spectra of charged particles in Z boson events, which are sensitive to medium modifications of the parton shower longitudinal structure, are also reported. Significant modifications in central Pb-Pb events compared to the pp reference data are also found for these observables.
Source :
Physical Review Letters
Date :
2022-03-23
Volume :
128
Issue :
12
Publisher :
American Physical Society
URI
http://hdl.handle.net/10679/8513https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.128.122301
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