45 research outputs found
Influence of finite volume effect on the Polyakov Quark-Meson model
In the current work, we study the influence of a finite volume on
Polyakov Quark-Meson model (PQM) order parameters, (fluctuations)
correlations of conserved charges and the quark-hadron phase boundary. Our
study of the PQM model order parameters and the (fluctuations) correlations of
conserved charges indicates a sizable shift of the quark-hadron phase boundary
to higher values of baryon chemical potential () and temperature ()
for decreasing the system volume. The detailed study of such effect could have
important implications for the extraction of the (fluctuations) correlations of
conserved charges of the QCD phase diagram from heavy ion data.Comment: 12 pages, 8 figure
Beam energy and system dependence of rapidity-even dipolar flow
New measurements of rapidity-even dipolar flow, v, are presented
for several transverse momenta, , and centrality intervals in Au+Au
collisions at and GeV, U+U collisions at
GeV, and Cu+Au, Cu+Cu, d+Au and p+Au collisions at
~GeV. The v shows characteristic dependencies
on , centrality, collision system and , consistent
with the expectation from a hydrodynamic-like expansion to the dipolar
fluctuation in the initial state. These measurements could serve as constraints
to distinguish between different initial-state models, and aid a more reliable
extraction of the specific viscosity
On SU(3) effective models and chiral phase-transition
The sensitivity of Polyakov Nambu-Jona-Lasinio (PNJL) model as an effective
theory of quark dynamics to chiral symmetry has been utilized in studying the
QCD phase-diagram. Also, Poyakov linear sigma-model (PLSM), in which
information about the confining glue sector of the theory was included through
Polyakov-loop potential. Furthermore, from quasi-particle model (QPM), the
gluonic sector of QPM is integrated to LSM in order to reproduce recent lattice
calculations. We review PLSM, QLSM, PNJL and HRG with respect to their
descriptions for the chiral phase-transition. We analyse chiral order-parameter
M(T), normalized net-strange condensate Delta_{q,s}(T) and chiral phase-diagram
and compare the results with lattice QCD. We conclude that PLSM works perfectly
in reproducing M(T) and Delta_{q,s}(T). HRG model reproduces Delta_{q,s}(T),
while PNJL and QLSM seem to fail. These differences are present in QCD chiral
phase-diagram. PLSM chiral boundary is located in upper band of lattice QCD
calculations and agree well with freeze-out results deduced from high-energy
experiments and thermal models. Also, we find that the chiral temperature
calculated from from HRG model is larger than that from PLSM. This is also
larger than the freeze-out temperatures calculated in lattice QCD and deduced
from experiments and thermal models. The corresponding temperature T and
chemical potential mu sets are very similar to that of PLSM. This might be
explained, because the chiral T and mu are calculated using different order
parameters; in HRG vanishing quark-antiquark condensate but in PLSM crossing
(equaling) chiral condensates and Polyakov loop potentials. The latter assumed
that the two phase transitions; chiral and deconfinement, take place at the
same temperature.Comment: 19 pages, 3 eps-figures accepted for publication in AHE
Collision system and beam energy dependence of anisotropic flow fluctuations
New measurements of two- and four-particle elliptic flow are used to
investigate flow fluctuations in collisions of U+U at =
193~GeV, Cu+Au at = 200~GeV and Au+Au at several beam energies.
These measurements highlight the dependence of these fluctuations on the
event-shape, system-size and beam energy and indicate a dominant role for
initial-state-driven fluctuations. These measurements could provide further
constraints for initial-state models, as well as for precision extraction of
the temperature-dependent specific shear viscosity