18,007 research outputs found
Hydrodynamic Description of Heavy Ion Collisions
We give a short review of hydrodynamic models at heavy ion collisions from
the point of view of initial conditions, an equation of states (EoS) and
freezeout process. Then we show our latest results of a combined fully
three-dimensional macroscopic/microscopic transport approach. In this model for
the early, dense, deconfined stage relativistic 3D-hydrodynamics of the
reaction and a microscopic non-equilibrium model for the later hadronic stage
where the equilibrium assumptions are not valid anymore are employed. Within
this approach we study the dynamics of hot, bulk QCD matter, which is being
created in ultra-relativistic heavy ion collisions at RHIC.Comment: 8 pages, 9 figures, latex, plenary presentation at the 19th
International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions
(QM2006), Shanghai, China Nov. 14-20, 200
Signals of the QCD Critical Point in Hydrodynamic Evolutions
The presence of a critical point in the QCD phase diagram can deform the
trajectories describing the evolution of the expanding fireball in the QCD
phase diagram. The deformation of the hydrodynamic trajectories will change the
transverse velocity dependence of the proton-antiproton ratio when the fireball
passes in the vicinity of the critical point. An unusual transverse velocity
dependence of the anti-proton/proton ratio in a narrow beam energy window would
thus signal the presence of the critical point.Comment: 4 pages, 6 figures, 21st International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions (QM2009) 30 Mar - 4 Apr 2009,
Knoxville, Tennesse
Analysis of the scalar mesons on the Lattice
We study the possibility that the scalar mesons exist as four-quark states.
The energy shift of two pseudoscalar mesons as a function of spatial lattice
size makes a distinction between bound states and scattering states of
four-quark states. We calculate the four-quark state in the quenched
approximation, ignoring the two-quark annihilation diagrams and the vacuum
channels. We perform a calculation of pseudoscalar meson scattering amplitudes,
using N_f=2 Wilson fermion and plaquette/Iwasaki gauge actions. We obtain the
indication that the four-quark states in the case of the isospin zero (I=0) and
two (I=2) channels are no bound states. And we find that the bound energy
depends strongly on pion mass rather than the ratio of pion mass to rho meson
mass.Comment: 7 pages, 4 figures, The 30th International Symposium on Lattice Field
Theor
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