The production of Z0 bosons at large rapidities in Pb–Pb collisions at √sNN = 5.02 TeV is reported. Z0 candidates are reconstructed in the dimuon decay channel (Z0 → μ+ μ−), based on muons selected with pseudo-rapidity −4.0 < η < −2.5 and pT > 20 GeV/c. The invariant yield and the nuclear modification factor, RAA, are presented as a function of rapidity and collision centrality. The value of RAA for the 0–20% central Pb–Pb collisions is 0.67 ± 0.11 (stat.) ± 0.03 (syst.) ± 0.06 (corr. syst.), exhibiting a deviation of 2.6σ from unity. The results are well-described by calculations that include nuclear modifications of the parton distribution functions, while the predictions using vacuum PDFs deviate from data by 2.3σ in the 0–90% centrality class and by 3σ in the 0–20% central collisions.
Measurement of Z0-boson production at large rapidities in Pb–Pb collisions at √sNN = 5.02 TeV
Camerini, P.;Fragiacomo, E.;Lea, R.;Luparello, G.;Margagliotti, G. V.;Piano, S.;Rui, R.;
2018-01-01
Abstract
The production of Z0 bosons at large rapidities in Pb–Pb collisions at √sNN = 5.02 TeV is reported. Z0 candidates are reconstructed in the dimuon decay channel (Z0 → μ+ μ−), based on muons selected with pseudo-rapidity −4.0 < η < −2.5 and pT > 20 GeV/c. The invariant yield and the nuclear modification factor, RAA, are presented as a function of rapidity and collision centrality. The value of RAA for the 0–20% central Pb–Pb collisions is 0.67 ± 0.11 (stat.) ± 0.03 (syst.) ± 0.06 (corr. syst.), exhibiting a deviation of 2.6σ from unity. The results are well-described by calculations that include nuclear modifications of the parton distribution functions, while the predictions using vacuum PDFs deviate from data by 2.3σ in the 0–90% centrality class and by 3σ in the 0–20% central collisions.File | Dimensione | Formato | |
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