The production of jets in association with Z bosons, reconstructed via the μ+μ− and e+e− decay channels, is studied in pp and, for the first time, in Pb-Pb collisions. Both data samples were collected by the CMS experiment at the LHC, at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The Pb-Pb collisions were analyzed in the 0%–30% centrality range. The back-to-back azimuthal alignment was studied in both pp and Pb-Pb collisions for Z bosons with transverse momentum p_T^Z > 60 GeV/c and a recoiling jet with p_T^jet > 30 GeV/c. The p_T imbalance x_jZ=p_T^jet/p_T^Z, as well as the average number of jet partners per Z, R_jZ, was studied in intervals of p_T^Z. The R_jZ is found to be smaller in Pb-Pb than in pp collisions, which suggests that in Pb-Pb collisions a larger fraction of partons associated with the Z bosons fall below the 30 GeV/c p_T^jet threshold because they lose energy.
Study of Jet Quenching with Z+jet Correlations in Pb-Pb and pp Collisions at sqrt(s_NN) = 5.02 TeV
Amapane, N.;Argiro, S.;Bellan, R.;Costa, M.;Covarelli, R.;Kiani, B.;Migliore, E.;Monaco, V.;Monteil, E.;Obertino, M. M.;Pacher, L.;Pinna Angioni, G. L.;Ravera, F.;Romero, A.;Sacchi, R.;Sola, V.;Solano, A.;
2017-01-01
Abstract
The production of jets in association with Z bosons, reconstructed via the μ+μ− and e+e− decay channels, is studied in pp and, for the first time, in Pb-Pb collisions. Both data samples were collected by the CMS experiment at the LHC, at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The Pb-Pb collisions were analyzed in the 0%–30% centrality range. The back-to-back azimuthal alignment was studied in both pp and Pb-Pb collisions for Z bosons with transverse momentum p_T^Z > 60 GeV/c and a recoiling jet with p_T^jet > 30 GeV/c. The p_T imbalance x_jZ=p_T^jet/p_T^Z, as well as the average number of jet partners per Z, R_jZ, was studied in intervals of p_T^Z. The R_jZ is found to be smaller in Pb-Pb than in pp collisions, which suggests that in Pb-Pb collisions a larger fraction of partons associated with the Z bosons fall below the 30 GeV/c p_T^jet threshold because they lose energy.File | Dimensione | Formato | |
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5.PhysRevLett.119.082301.pdf
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