Speaker
Elena Bratkovskaya
(FIAS)
Description
We study charm and bottom production in ultra-relativistic heavy-ion collisions by using
the Parton-Hadron-String Dynamics (PHSD) transport approach.
The charm and bottom quarks are produced through initial binary nucleon-nucleon collisions
by using the PYTHIA event generator taking into account the (anti-)shadowing
incorporated in the EPS09 package. The produced heavy quarks interact with off-shell
massive partons in the quark-gluon plasma and are hadronized into D and B mesons through
coalescence or fragmentation close to the critical energy density, and then interact
with hadrons in the final hadronic stage with scattering cross sections calculated
in an effective Lagrangian approach with heavy-quark spin symmetry. The PHSD results
show a reasonable $R_{AA}$ and elliptic flow of D mesons in comparison to the experimental
data for Au+Au collisions at $\sqrt{s_{NN}}$ =200 GeV from the STAR Collaboration as well
as for Pb+Pb collisions at $\sqrt{s_{NN}}$ =2.76 TeV from the ALICE Collaboration.
Also we obtain a good description of the PHENIX data on $R_{AA}$ and $v_2$ of
a single electron when including the feed back from the B-meson decay which is important
at large $p_T$.
We find that in the PHSD the energy loss of $D$ mesons at high $p_T$ can be dominantly
attributed to partonic scattering while the actual shape of $R_{AA}$ versus $p_T$
reflects the heavy-quark hadronization scenario, i.e. coalescence versus fragmentation.
Also the hadronic rescattering is important for the $R_{AA}$ at low $p_T$ and enhances
the $D$-meson elliptic flow $v_2$.
We also study the effect of temperature-dependent off-shell charm quarks in relativistic
heavy-ion collisions. We find that the scattering cross sections are only moderately
affected by off-shell charm degrees of freedom. However, the position of the peak of
$R_{AA}$ for D mesons depends on the strength of the scalar partonic forces which
also have an impact on the D meson elliptic flow. The comparison with experimental
data on the $R_{AA}$ suggests that the repulsive force is weaker for off-shell charm
quarks as compared to that for light quarks. Furthermore, the effects from radiative
charm energy loss appear to be low compared to the collisional energy loss up to
transverse momenta of ~ 15 GeV/c.
| On behalf of collaboration: | None |
|---|
Author
Elena Bratkovskaya
(FIAS)
Co-authors
Daniel Cabrera
(Valencia Uni.)
Hamza Berrehrah
(Frankfurt Uni.)
Juan Torres-Rincon
(Frankfurt Uni.)
Laura Tolos
(Institut de Ciencies de l'Espai, Barcelona)
Taesoo Song
(Frankfurt Uni.)
Wolfgang Cassing
(University of Giessen)
