4 research outputs found
Early dynamics of transversally thermalized matter
We argue that the idea that the parton system created in relativistic
heavy-ion collisions is formed in a state with transverse momenta close to
thermodynamic equilibrium and its subsequent dynamics at early times is
dominated by pure transverse hydrodynamics of the perfect fluid is compatible
with the data collected at RHIC. This scenario of early parton dynamics may
help to solve the problem of early equilibration.Comment: 4 pages, 2 figures, Talk given by M. Chojnacki at Quark Matter 2008,
Jaipur, Indi
Early dynamics of transversally thermalized matter
We argue that the idea that the parton system created in relativistic
heavy-ion collisions is formed in a state with transverse momenta close to
thermodynamic equilibrium and its subsequent dynamics at early times is
dominated by pure transverse hydrodynamics of the perfect fluid is compatible
with the data collected at RHIC. This scenario of early parton dynamics may
help to solve the problem of early equilibration.Comment: 4 pages, 2 figures, Talk given by M. Chojnacki at Quark Matter 2008,
Jaipur, Indi
Highly-anisotropic and strongly-dissipative hydrodynamics with transverse expansion
A recently formulated framework of highly-anisotropic and
strongly-dissipative hydrodynamics (ADHYDRO) is used to describe the evolution
of matter created in ultra-relativistic heavy-ion collisions. New developments
of the model contain: the inclusion of asymmetric transverse expansion
(combined with the longitudinal boost-invariant flow) and comparisons of the
model results with the RHIC data, which have become possible after coupling of
ADHYDRO with THERMINATOR. Various soft-hadronic observables (the
transverse-momentum spectra, the elliptic flow coefficient v_2, and the HBT
radii) are calculated for different initial conditions characterized by the
value of the initial pressure asymmetry. We find that as long as the initial
energy density profile is unchanged the calculated observables remain
practically the same. This result indicates the insensitivity of the analyzed
observables to the initial anisotropy of pressure and suggests that the
complete thermalization of the system may be delayed to easily acceptable times
of about 1 fm/c
Temperature dependent sound velocity in hydrodynamic equations for relativistic heavy-ion collisions
We analyze the effects of different forms of the sound-velocity function
cs(T) on the hydrodynamic evolution of matter formed in the central region of
relativistic heavy-ion collisions. At high temperatures (above the critical
temperature Tc) the sound velocity is calculated from the recent lattice
simulations of QCD, while in the low temperature region it is obtained from the
hadron gas model. In the intermediate region we use different interpolations
characterized by the values of the sound velocity at the local maximum (at T =
0.4 Tc) and local minimum (at T = Tc). In all considered cases the temperature
dependent sound velocity functions yield the entropy density, which is
consistent with the lattice QCD simulations at high temperature. Our
calculations show that the presence of a distinct minimum of the sound velocity
leads to a very long (about 20 fm/c) evolution time of the system, which is not
compatible with the recent estimates based on the HBT interferometry. Hence, we
conclude that the hydrodynamic description is favored in the case where the
cross-over phase transition renders the smooth sound velocity function with a
possible shallow minimum at Tc.Comment: 6 pages, 3 figures, talk given at SQM'07 Levoca, Slovaki