7,100 research outputs found

### Early thermalization of quark-gluon matter by elastic 3-to-3 scattering

The early thermalization is crucial to the quark-gluon plasma as a perfect
liquid and results from many-body scattering. We calculate squared amplitudes
for elastic parton-parton-parton scattering in perturbative QCD. Transport
equations with the squared amplitudes are established and solved to obtain the
thermalization time of initially produced quark-gluon matter and the initial
temperature of quark-gluon plasma. We find that the thermalization times of
quark matter and gluon matter are different.Comment: 5 pages, 1 figure, proceedings for Extreme QCD 201

### Early Thermalization at RHIC

Triple-gluon elastic scatterings are briefly reviewed since the scatterings
explain the early thermalization puzzle in Au-Au collisions at RHIC energies. A
numerical solution of the transport equation with the triple-gluon elastic
scatterings demonstrates gluon momentum isotropy achieved at a time of the
order of 0.65 fm/c. Triple-gluon scatterings lead to a short thermalization
time of gluon matter.Comment: LaTex, 8 pages and 4 figures, talk presented in the Weihai workshop
on relativistic heavy ion collision

### Early thermalization of quark-gluon matter initially created in high-energy nucleus-nucleus collisions

Elastic parton-parton-parton scattering is briefly reviewed and is included
in transport equations of quark-gluon matter. We solve the transport equations
and get thermal states from initially produced quark-gluon matter. Both gluon
matter and quark matter take early thermalization, but gloun matter has a
shorter thermalization time than quark matter.Comment: 7 pages, 4 figures, proceedings for the 29th Winter Workshop on
Nuclear Dynamic

### Origin of Temperature of Quark-Gluon Plasma in Heavy Ion Collisions

Initially produced quark-gluon matter at RHIC and LHC does not have a
temperature. A quark-gluon plasma has a high temperature. From this quark-gluon
matter to the quark-gluon plasma is the early thermalization or the rapid
creation of temperature. Elastic three-parton scattering plays a key role in
the process. The temperature originates from the two-parton scattering, the
three-parton scattering, the four-parton scattering and so forth in quark-gluon
matter.Comment: 6 pages, proceedings for the XXX-th International Workshop on High
Energy Physic

### Integral bases of cluster algebras and representations of tame quivers

In \cite{CK2005} and \cite{SZ}, the authors constructed the bases of cluster
algebras of finite types and of type $\widetilde{A}_{1,1}$, respectively. In
this paper, we will deduce $\mathbb{Z}$-bases for cluster algebras of affine
types.Comment: 28 pages, an improvement of arXiv:0811.367

### Temperature dependence of cross sections for meson-meson nonresonant reactions in hadronic matter

We study unpolarized cross sections for the endothermic nonresonant
reactions: pion pion to rho rho for I=2, KK to K*K* for I=1, KK* to K*K* for
I=1, pion K to rho K* for I=3/2, pion K* to rho K* for I=3/2, rho K to rho K*
for I=3/2, and pion K* to rho K for I=3/2, which take place in hadronic matter.
We provide a potential that is given by perturbative QCD with loop corrections
at short distances, becomes a distance-independent and temperature-dependent
value at long distances, and has a spin-spin interaction with relativistic
modifications. The Schrodinger equation with the potential yields
temperature-dependent meson masses and mesonic quark-antiquark relative-motion
wave functions. In the first Born approximation with the quark-interchange
mechanism, the temperature dependence of the potential, meson masses and wave
functions brings about temperature dependence of unpolarized cross sections for
the seven nonresonant reactions. Noticeably, rapid changes of pion and K radii
cause an increase in peak cross sections while the temperature approaches the
critical temperature. Parametrizations of the numerical cross sections are
given for their future applications in heavy ion collisions.Comment: 24 pages, 8 figure

### A $\mathbb{Z}$-basis for the cluster algebra associated to an affine quiver

The canonical bases of cluster algebras of finite types and rank 2 are given
explicitly in \cite{CK2005} and \cite{SZ} respectively. In this paper, we will
deduce $\mathbb{Z}$-bases for cluster algebras for affine types
$\widetilde{A}_{n,n},\widetilde{D}$ and $\widetilde{E}$. Moreover, we give an
inductive formula for computing the multiplication between two generalized
cluster variables associated to objects in a tube.Comment: 21 page

### Relation between quark-antiquark potential and quark-antiquark free energy in hadronic matter

In the high-temperature quark-gluon plasma and its subsequent hadronic matter
created in a high-energy nucleus-nucleus collision, the quark-antiquark
potential depends on the temperature. The temperature-dependent potential is
expected to be derived from the free energy obtained in lattice gauge theory
calculations. This requires one to study the relation between the
quark-antiquark potential and the quark-antiquark free energy. When the
system's temperature is above the critical temperature, the potential of a
heavy quark and a heavy antiquark almost equals the free energy, but the
potential of a light quark and a light antiquark, of a heavy quark and a light
antiquark and of a light quark and a heavy antiquark is substantially larger
than the free energy. When the system's temperature is below the critical
temperature, the quark-antiquark free energy can be taken as the
quark-antiquark potential. This allows one to apply the quark-antiquark free
energy to study hadron properties and hadron-hadron reactions in hadronic
matter.Comment: 11 page

### Charmonium dissociation in collision with phi meson in hadronic matter

The phi-charmonium dissociation reactions in hadronic matter are studied.
Unpolarised cross sections for 12 reactions are calculated in the Born
approximation, in the quark-interchange mechanism and with a
temperature-dependent quark potential. The potential leads to remarkable
temperature dependence of the cross sections. With the cross sections and the
phi distribution function we calculate the dissociation rates of the charmonia
in the interactions with the phi meson in hadronic matter. The dependence of
the rates on temperature and charmonium momentum is meaningful to the influence
of phi mesons on charmonium suppression.Comment: 21 pages, 12 figure

### Realizing Enveloping Algebras via Varieties of Modules

By using the Ringel-Hall algebra approach, we investigate the structure of
the Lie algebra $L(\Lambda)$ generated by indecomposable constructible sets in
the varieties of modules for any finite dimensional $\mathbb{C}$-algebra
$\Lambda.$ We obtain a geometric realization of the universal enveloping
algebra $R(\Lambda)$ of $L(\Lambda).$ This generalizes the main result of
Riedtmann in \cite{R}. We also obtain Green's theorem in \cite{G} in a
geometric form for any finite dimensional $\mathbb{C}$-algebra $\Lambda$ and
use it to give the comultiplication formula in $R(\Lambda).

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