Speaker
Description
W and Z bosons are massive weakly interacting probes; insensitive to the strong interaction, they are clean observables of the initial state of heavy-ion collisions. Despite their low production rates, their relatively clean signatures in the leptonic decay channels allow their study in heavy-ion collisions at the LHC. Their measurement in p--Pb and Pb--Pb collisions provides constraints on the nuclear parton distribution functions (nPDFs). In particular, the W and Z rapidity-differential production cross sections and the decay lepton charge asymmetry as a function of rapidity provide stringent tests of nPDFs. Electroweak boson measurements in heavy-ion collisions also constitute a tool to validate the binary scaling of hard processes as well as a reference for medium-induced effects on other probes.
The measurement of electroweak boson production in p--Pb and Pb--Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV with ALICE will be presented. The ALICE muon spectrometer capabilities to detect high $p_{\rm T}$ muons will be exploited to reconstruct electroweak bosons at large rapidity (2.5<$y_{\rm lab}$<4.0). These measurements are complementary to the ATLAS and CMS ones at central rapidity, and more precise than LHCb ones with a similar rapidity coverage. Rapidity-differential measurements of W and Z, as well as of the charge asymmetry of W-decay leptons, in p--Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV will be discussed. First measurements of Z production cross section in Pb--Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV will be shown. Results will be compared with model calculations including nPDFs. In addition, the centrality dependence of W yields in p--Pb collisions and of Z production in Pb--Pb collisions will be discussed as a test of binary scaling.
| Preferred Track | Electromagnetic Probes |
|---|---|
| Collaboration | ALICE |
