141 research outputs found
Pion and Kaon Spectra from Distributed Mass Quark Matter
After discussing some hints for possible masses of quasiparticles in quark
matter on the basis of lattice equation of state, we present pion and kaon
transverse spectra obtained by recombining quarks with distributed mass and
thermal cut power-law momenta as well as fragmenting by NLO pQCD with intrinsic
{and nuclear} broadening.Comment: Talk given at SQM 200
Quantum Chaos in Compact Lattice QED
Complete eigenvalue spectra of the staggered Dirac operator in quenched
compact QED are studied on and lattices. We
investigate the behavior of the nearest-neighbor spacing distribution as
a measure of the fluctuation properties of the eigenvalues in the strong
coupling and the Coulomb phase. In both phases we find agreement with the
Wigner surmise of the unitary ensemble of random-matrix theory indicating
quantum chaos. Combining this with previous results on QCD, we conjecture that
quite generally the non-linear couplings of quantum field theories lead to a
chaotic behavior of the eigenvalues of the Dirac operator.Comment: 11 pages, 4 figure
Quark coalescence in the mid rapidity region at RHIC
We utilize the ALCOR model for mid-rapidity hadron number predictions at AGS,
SPS and RHIC energies. We present simple fits for the energy dependence of
stopping and quark production.Comment: Talk given at SQM2001, Frankfurt, (LaTeX 8 pages, 5 .ps figs
Adventures of the Coupled Yang-Mills Oscillators: I. Semiclassical Expansion
We study the quantum mechanical motion in the potentials with
, which arise in the spatially homogeneous limit of the Yang-Mills (YM)
equations. These systems show strong stochasticity in the classical limit
() and exhibit a quantum mechanical confinement feature. We
calculate the partition function going beyond the Thomas-Fermi (TF)
approximation by means of the semiclassical expansion using the Wigner-Kirkwood
(WK) method. We derive a novel compact form of the differential equation for
the WK function. After separating the motion in the channels of the
equipotential surface from the motion in the central region, we show that the
leading higher-order corrections to the TF term vanish up to eighth order in
, if we treat the quantum motion in the hyperbolic channels correctly by
adiabatic separation of the degrees of freedom. Finally, we obtain an
asymptotic expansion of the partition function in terms of the parameter
Adventures of the Coupled Yang-Mills Oscillators: II. YM-Higgs Quantum Mechanics
We continue our study of the quantum mechanical motion in the
potentials for , which arise in the spatially homogeneous limit of the
Yang-Mills (YM) equations. In the present paper, we develop a new approach to
the calculation of the partition function beyond the Thomas-Fermi (TF)
approximation by adding a harmonic (Higgs) potential and taking the limit , where is the vacuum expectation value of the Higgs field. Using the
Wigner-Kirkwood method to calculate higher-order corrections in , we
show that the limit leads to power-like singularities of the type
, which reflect the possibility of escape of the particle along the
channels in the classical limit. We show how these singularities can be
eliminated by taking into account the quantum fluctuations dictated by the form
of the potential
Parton Equilibration in Relativistic Heavy Ion Collisions
We investigate the processes leading to phase-space equilibration of parton
distributions in nuclear interactions at collider energies. We derive a set of
rate equations describing the chemical equilibration of gluons and quarks
including medium effects on the relevant QCD transport coefficients, and
discuss their consequences for parton equilibration in heavy ion collisions.Comment: 18 pages, 6 Figures appended as uuencoded PostScript files, (no
changes in the previously submitted manuscript), DUKE-TH-93-4
Dynamical Evolution of the Scalar Condensate in Heavy Ion Collisions
We derive the effective coarse-grained field equation for the scalar
condensate of the linear sigma model in a simple and straightforward manner
using linear response theory. The dissipative coefficient is calculated at tree
level on the basis of the physical processes of sigma-meson decay and of
thermal sigma-mesons and pions knocking sigma-mesons out of the condensate. The
field equation is solved for hot matter undergoing either one or three
dimensional expansion and cooling in the aftermath of a high energy nuclear
collision. The results show that the time constant for returning the scalar
condensate to thermal equilibrium is of order 2 fm/c.Comment: 19 pages, 3 figures are embedded at the end. The effect of the time
dependence of the condensate v is included in this revised version. Numerical
work is redone accordingl
Inflationary Reheating in Grand Unified Theories
Grand unified theories may display multiply interacting fields with strong
coupling dynamics. This poses two new problems: (1) What is the nature of
chaotic reheating after inflation, and (2) How is reheating sensitive to the
mass spectrum of these theories ? We answer these questions in two interesting
limiting cases and demonstrate an increased efficiency of reheating which
strongly enhances non-thermal topological defect formation, including monopoles
and domain walls. Nevertheless, the large fluctuations may resolve this
monopole problem via a modified Dvali-Liu-Vachaspati mechanism in which
non-thermal destabilsation of discrete symmetries occurs at reheating.Comment: 4 pages, 5 ps figures - 1 colour, Revtex. Further (colour & 3-D)
figures available from http://www.sissa.it/~bassett/reheating/ . Matched to
version to appear in Phys. Rev. let
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