Speaker
francesco scardina
(INFN Catania)
Description
The heavy quarks constitutes a unique probe of the quark-gluon plasma properties.
Both at RHIC and LHC energies it has been observed a puzzling correlation
between the nuclear modification factor $R_{AA}$ and the elliptic flow $v_2$ that has challenged
all the existing models, especially for D mesons, We discuss how the treatment of the
charm quark dynamics according to a Boltzmann or a Langevin dynamics can be responsible
for a large part of such a puzzle. In particular, we see that depending on the angular and
temperature dependence of the scattering matrix the $v_2$ can be
quite different. In particular, once one reproduces the $R_{AA}$ with both a Boltzmann
and/or a Langevin approach the $v_2(p_T)$ that is build-up can be as different as a 50-80%.
This together with a coalescence hadronization mechanism strongly quenches the puzzling
$R_{AA}$ and $v_2$ observation.
Differences between Boltzmann and Langevin dynamics can be traced back to the fact that
especially for large screening mass (nearly isotropic scatterings) the transferred momentum
is not small but comparable with the charm mass as well as to the average momentum of the bulk.
On the other hand such differences disappear for bottom quarks which are predicted to be free
of the ambiguities coming from the difference between a Boltzmann or a Langevin approach,
and should more properly considered as heavy quarks as regards their transport in the QGP.
Our study allows also to shed lights on the different predictions of several models
currently compared with the first data at LHC on D mesons.
Reference:
1) S. K. Das, F. Scardina, V. Greco, arXiv:1312.6857 [nucl-th]
2) H. Van Hees, M. Mannarelli, V. Greco and R. Rapp, Phys. Rev. Lett.100,192301 (2008)
3)V. Greco, C. M. Ko and R. Rapp, Phys. Lett. B 595,202 (2004)
Authors
Vincenzo Greco
(University of Catania)
francesco scardina
(INFN Catania)
Co-authors
Salvatore Plumari
(University of Catania (Italy))
Santosh Kumar Das
(University of Catania, Italy)
