Speaker
Description
Heavy quarks, i.e. charm and beauty, are sensitive probes to study the properties of the strongly-interacting matter created in heavy-ion collisions at ultra-relativistic energies, since they are mainly produced in initial hard scattering processes and experience the entire evolution of the system.
The heavy quarks traversing the medium lose energy via collisional and radiative processes in the interaction with the medium constituents. The heavy-flavour energy loss can be investigated with measurements of the modification of the transverse momentum distribution of heavy-flavour particles in heavy-ion collisions with respect to binary-scaled pp collisions (nuclear modification factor $R_{\rm{AA}}$). An observable that complements the investigation of the interaction of heavy quarks with the medium is the elliptic flow of heavy-flavour particles, which is defined as the second harmonic ($v_{2}$) of the Fourier expansion of the particle azimuthal distribution in momentum space. The measurement of the heavy-flavour particle $v_{2}$ at low transverse momentum ($p_{\rm T}$) provides insight into the collective motion of heavy quarks in the medium, while the heavy-flavour particle $v_{2}$ at high $p_{\rm T}$ is sensitive to the path-length dependence of the energy loss of heavy quarks in the almond-shaped overlap area in non-central collisions.
The semi-leptonic decay channel of open heavy-flavour hadrons is well suited for heavy-flavour studies in ALICE, since the branching ratio is relatively large (10$\%$) and ALICE has an unique capability for identification of electrons at mid-rapidity ($|y| < 0.8$) and muons at forward rapidity ($2.5 < y < 4$) over a wide $p_{\rm T}$ range.
In this talk, we will present the ALICE results on the nuclear modification factor and elliptic flow of open heavy flavour hadrons via their semi-electronic decays at mid-rapidity and via their semi-muonic decay channel at forward rapidity in Pb–Pb collisions. Progress on the measurements of leptons from heavy-flavour and beauty-hadron decays in Pb–Pb collisions at $\sqrt{s_{\rm{NN}}} = 2.76$ TeV will be discussed. The first results on the $R_{\rm{AA}}$ and $v_{2}$ of electrons from heavy-flavour hadron decays in Pb–Pb collisions at $\sqrt{s_{\rm{NN}}} = 5.02$ TeV and prospects for measurements of electrons from beauty-hadron decays will be presented. The latest results concerning the measurements of the production cross section and nuclear modification factor of muons from heavy-flavour hadron decays as a function of $p_{\rm T}$ and collision centrality in Pb–Pb collisions at $\sqrt{s_{\rm{NN}}} = 5.02$ TeV will also be shown. The results will be compared with model calculations including the interaction of heavy quarks with the medium.
| Preferred Track | Open Heavy Flavors |
|---|---|
| Collaboration | ALICE |
