1) Title: Dynamical approach to parton coalescence
A recent exciting observation in Au+Au reactions at RHIC is the observed
quark number scaling of differential elliptic flow v2(pT) [1].
Hadronization via quark coalescence[2-4] provides a natural
explanation[3] for this phenomenon. In the coalescence model, the
flow of hadrons is directly related to that of constituent quarks, making
it possible to infer the quark flows from experimental data. I will
compare results for light and charm hadrons i) based on the simple
coalescence formulas[2,3] and ii) from a new approach[4] that
incorporates quark coalescence into a dynamical transport model.
[1] P. Sorensen [STAR Coll.], J. Phys G. 30, S217 (2004);
J. Adams et al. [STAR Coll.], Phys. Rev. Lett. 92, 052302 (2004);
S. S. Adler et al. [PHENIX Coll.], Phys. Rev. Lett. 91, 182301 (2003).
[2] V. Greco. C.-M. Ko, and P. Levai, Phys. Rev. Lett. 90, 20302 (2003);
R. J. Fries et al., Phys. Rev. Lett. 90, 202303 (2003)
[3] D. Molnar and S. A. Voloshin, Phys. Rev. Lett. 91, 092301 (2003);
Z.-W. Lin and D. Molnar, Phys. Rev. C68, 044901 (2003);
R. J. Fries et al., Phys. Rev. C68, 044902 (2003)
[4] D. Molnar, nucl-th/0403035
2) Title: Dissipation and elliptic flow at RHIC
Recent data from RHIC for Au+Au reactions at E_cm ~ 130-200 GeV / nucleon
show a large anisotropy of particle production in the transverse plane,
characterized by the elliptic flow coefficient v2(pT). The anisotropy can
be reproduced from ideal hydrodynamics[1], providing a strong
argument for rapid thermalization in these reactions. On the other
hand, parton kinetic theory[2] can also reproduce the data, if the
system is an order of magnitude more opaque than a perturbative
parton plasma.
A common belief is that the kinetic theory calculation demonstrated the
kinetic equilibration of the dense parton plasma. I show that this is not
the case because dissipative effects are large even at such extreme
opacities[3]. I will also investigate how the classical transport
results are affected when unitarity bounds on scattering rates
(a genuine quantum effect) are taken into account.
[1] P. Huovinen et al., PLB 503, 58 (2001);
P.F. Kolb, J. Sollfrank and U.W. Heinz, PRC 62, 054909 (2000);
D. Teaney, J. Lauret and E.V. Shuryak, nucl-th/0110037.
[2] D. Molnar and M. Gyulassy, NPA697, 495 (2002); A703, 893(E) (2002);
B. Zhang, M. Gyulassy and C.M. Ko, PLB 455, 45 (1999).
[3] D. Molnar and P. Huovinen, nucl-th/0404065