Measurement of the D-meson nuclear modification factor and elliptic flow in Pb–Pb collisions at √SNN = 5.02 TeV with ALICE at the LHC

Fabrizio Grosa,A Mischke,P Kuijer

doi:10.1051/epjconf/201817118007

Fabrizio Grosa, A Mischke + Show 1 more

Open Access

https://doi.org/10.1051/epjconf/201817118007

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Abstract

Heavy-flavour hadrons are recognised as a powerful probe for the characterisation of the deconfined medium created in heavy-ion collisions, the Quark-Gluon Plasma (QGP). The ALICE Collaboration measured the production of D0, D+, D*+ and [see formula in PDF] mesons in Pb–Pb collisions at [see formula in PDF] = 5.02 TeV. The measurement of the nuclear modification factor (RAA) provides a strong evidence of the in-medium parton energy loss. The comparison between the [see formula in PDF] and the non-strange D-meson RAA can help to study the hadronisation mechanism of the charm quark in the QGP. In mid-central collisions, the measurement of the D-meson elliptic flow v2 at low transverse momentum (pT) gives insight into the participation of the charm quark into the collective motion of the system, while at high pT it constrains the path-length dependence of the energy loss. The [see formula in PDF] v2, measured for the first time at the LHC, is found to be compatible to that of non-strange D mesons and positive with a significance of about 2.6 σ. The coupling of the charm quark to the light quarks in the underlying medium is further investigated for the first time with the application of the Event-Shape Engineering (ESE) technique to D-meson elliptic flow.

Highlights

IntroductionIn this scenario, the measurement of heavy-flavour hadrons with strangequark content (e.g. the D+s meson) is crucial to understand the modification of the charm-quark hadronisation in the deconfined medium [10]
(pT) gives insight into the participation of the charm quark into the collective motion of the system, while at high pT it constrains the path-length dependence of the energy loss
Complementary information on the interaction of heavy quarks with the Quark-Gluon Plasma (QGP) is provided by the measurement of the azimuthal anisotropy in the momentum distribution of heavy-flavour hadrons and, in particular, by the elliptic flow v2 = cos(2(φ − Ψ2)), which is defined as the second-order harmonic coefficient of the Fourier expansion of the azimuthal distribution with respect to the reaction plane angle Ψ2

Summary

Introduction

In this scenario, the measurement of heavy-flavour hadrons with strangequark content (e.g. the D+s meson) is crucial to understand the modification of the charm-quark hadronisation in the deconfined medium [10]. Complementary information on the interaction of heavy quarks with the QGP is provided by the measurement of the azimuthal anisotropy in the momentum distribution of heavy-flavour hadrons and, in particular, by the elliptic flow v2 = cos(2(φ − Ψ2)) , which is defined as the second-order harmonic coefficient of the Fourier expansion of the azimuthal distribution with respect to the reaction plane angle Ψ2. The measurement of the v2 at low pT helps to quantify to which extent heavy quarks are influenced by the collective dynamics of the underlying medium, while at high pT has the potential to constrain the path-length dependence of the parton energy loss in the QGP [11,12,13]

D-meson reconstruction

Prompt D-meson nuclear modification factor and elliptic flow

Findings

Conclusions