Measurement of Z0-boson production at large rapidities in Pb–Pb collisions at sNN=5.02TeV


Acharya S., Adamová D., Adolfsson J., Aggarwal M., Aglieri Rinella G., Agnello M., ...More

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, vol.780, pp.372-383, 2018 (SCI-Expanded) identifier identifier

Abstract

The production of Z0 bosons at large rapidities in Pb–Pb collisions at sNN=5.02TeV 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>20GeV/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.