Speaker
Dr
Li Yan
(IPhT Saclay)
Description
In this talk, I would like to report the results of our recent work on the thermalization of gluons and $N_f$ flavors of massless quarks and antiquarks in a spatially homogeneous
system. First, we give two coupled transport equations for gluons and quarks (and antiquarks), which are derived within the diffusion approximation of
the Boltzmann equation with only $2\leftrightarrow 2$ processes included in the collision term. These transport equations are solved
numerically in order to study the thermalization of the quark-gluon plasma. Next, we discuss three different patterns of the thermalization of the quark-gluon system. At initial time, we assume that no quarks or antiquarks are present
and we choose the gluon distribution in the form $f = f_0~\theta\left(1-\frac{p}{Q_s} \right) $ with $Q_s$ the saturation momentum and
$f_0$ a constant. The subsequent evolution of systems
may, or may not, lead to the formation of a (transient) Bose condensate, depending on the value of $f_0$. The three patterns of thermalization are as follows: (a) thermalization
without gluon Bose-Einstein condensates (BEC) for $f_0\leq f_{0t}$,
(b) thermalization with transient BEC for $f_{0t} < f_0 \leq f_{0c}$ and (c) thermalization with BEC for $f_{0c} < f_0 $. Here, the values of $f_{0t} $ and $f_{0c} $ depend on $N_f$. When $f_0 \geq 1 > f_{0c}$, the formation of BEC starts at a finite time $t_c\sim\frac{1}{(\alpha_s f_0)^2}\frac{1}{Q_s}$. We also find that the equilibration time
for $N_f = 3$ is typically about 5 to 6 times longer than that for $N_f = 0$ at the same $Q_s$.
| On behalf of collaboration: | None |
|---|
Primary authors
Dr
Bin Wu
(IPhT Saclay)
Dr
Li Yan
(IPhT Saclay)
Co-author
Prof.
Jean-Paul Blaizot
(IPhT Saclay)
