Open heavy-flavour and electroweak boson measurements via the (di-)muonic decay channel with ALICE at the LHC

Kgotlaesele Johnson Senosi

doi:10.1088/1742-6596/832/1/012033

Abstract

Heavy flavours (charm and beauty) and electroweak bosons (W and Z) are produced in initial hard partonic scatterings. The former interact strongly with the medium formed in ultra-relativistic heavy-ion collisions throughout its evolution, thus making them well suited to investigate its properties. Furthermore, heavy-flavour measurements in proton-nucleus collisions can be used to investigate initial-state effects whereas in proton-proton (pp) collisions they are considered an important test for perturbative Quantum ChromoDynamics (pQCD) predictions. In addition, open heavy-flavour measurements in pp collisions are used as a reference for proton-lead (p–Pb) and lead-lead (Pb–Pb) collisions. On the other hand, electroweak bosons and their leptonic decay products only interact weakly with the QCD matter and thus are suitable probes to test the validity of binary-collision scaling of hard processes. Moreover, their measurements in p–Pb collisions could help to constrain nuclear parton distribution functions. The ALICE muon spectrometer allows the measurement of open heavy flavour, W- and Z-boson production at forward rapidity (−4.0 < η < −2.5) exploiting their (di)muonic decay channel. In this talk the results obtained with the LHC Run I data in pp, p–Pb and Pb–Pb collisions will be discussed and compared with theoretical predictions.

Highlights

Due to their large masses, open heavy flavours and electroweak bosons (W and Z) are produced in initial hard partonic processes
Heavy-flavour measurements in proton-nucleus collisions can be used to investigate initial-state effects whereas in proton-proton collisions they are considered an important test for perturbative Quantum ChromoDynamics predictions
Initial-state effects [6, 7] or cold nuclear matter (CNM) effects, studied in proton-lead (p–Pb) collisions, complicate the interpretation of any deviation from unity of the RAA in terms of energy loss effects, for a thorough treatment, heavy-ion collisions need to be studied in conjunction with proton-proton and p–Pb collisions

Summary

Introduction

Due to their large masses, open heavy flavours (charm and beauty) and electroweak bosons (W and Z) are produced in initial hard partonic processes. Their weak coupling nature in the leptonic decay channel makes them good probes to study CNM effects They give access to the initial-state properties in nuclear collisions and their yields provide a benchmark to validate the binary-scaling of hard processes [12]. The production of open heavy flavours, W- and Z-bosons in proton-lead collisions (p–Pb) provides an excellent tool to study cold nuclear matter (CNM) effects [6, 7, 12] This control experiment (p–Pb) is used to understand whether the effects seen in heavy-ion collisions are a combination of initial and final state effects. The RpPb of open heavy flavour decay muons in p–Pb collisions is shown in Figure 2 at backward (left) and forward (right) rapidity. The Ncoll -normalized yield is independent of event activity and compatible among estimators within uncertainties which is consistent with the results by CMS and ATLAS, indicating binary scaling of hard processes in heavy ion collisions

Conclusions

24 Multiplicity estimators