1,334 research outputs found
A formula for charmonium suppression
In this work a formula for charmonium suppression obtained by Matsui in 1989
is analytically generalized for the case of complex c-cbar potential described
by a 3-dimensional and isotropic time-dependent harmonic oscillator (THO). It
is suggested that under certain conditions the formula can be applied to
describe J/\psi suppression in heavy-ion collisions at CERN-SPS, RHIC, and LHC
with the advantage of analytical tractability.Comment: 4 pages, no figures, to appear in Phys. At. Nucl., vol. 7
Compactified rotating branes in the matrix model, and excitation spectrum towards one loop
We study compactified brane solutions of type R^4 x K in the IIB matrix
model, and obtain explicitly the bosonic and fermionic fluctuation spectrum
required to compute the one-loop effective action. We verify that the one-loop
contributions are UV finite for R^4 x T^2, and supersymmetric for R^3 x S^1.
The higher Kaluza-Klein modes are shown to have a gap in the presence of flux
on T^2, and potential problems concerning stability are discussed.Comment: 14 pages, 1 figure; v2 typos correcte
Thermodynamic properties of a simple, confining model
We study the equilibrium thermodynamics of a simple, confining, DSE-model of
2-flavour QCD at finite temperature and chemical potential. The model has two
phases: one characterised by confinement and dynamical chiral symmetry
breaking; and the other by their absence. The phase boundary is defined by the
zero of the vacuum-pressure difference between the confined and deconfined
phases. Chiral symmetry restoration and deconfinement are coincident with the
transition being of first order, except for , where it is second order.
Nonperturbative modifications of the dressed-quark propagator persist into the
deconfined domain and lead to a dispersion law modified by a
dynamically-generated, momentum-dependent mass-scale. This entails that the
Stefan-Boltzmann limit for the bulk thermodynamic quantities is attained only
for large values of temperature and chemical potential.Comment: 11 pages, LaTeX, epsfig.sty, elsart.st
Heavy flavor kinetics at the hadronization transition
We investigate the in-medium modification of the charmonium breakup processes
due to the Mott effect for light (pi, rho) and open-charm (D, D*)
quark-antiquark bound states at the chiral/deconfinement phase transition. The
Mott effect for the D-mesons effectively reduces the threshold for charmonium
breakup cross sections, which is suggested as an explanation of the anomalous
J/psi suppression phenomenon in the NA50 experiment. Further implications of
finite-temperature mesonic correlations for the hadronization of heavy flavors
in heavy-ion collisions are discussed.Comment: 4 pages, 2 figures, Contribution to SQM2001 Conference, submitted to
J. Phys.
A New Approach to Non-Commutative U(N) Gauge Fields
Based on the recently introduced model of arXiv:0912.2634 for non-commutative
U(1) gauge fields, a generalized version of that action for U(N) gauge fields
is put forward. In this approach to non-commutative gauge field theories, UV/IR
mixing effects are circumvented by introducing additional 'soft breaking' terms
in the action which implement an IR damping mechanism. The techniques used are
similar to those of the well-known Gribov-Zwanziger approach to QCD.Comment: 11 pages; v2 minor correction
On Non-Commutative U*(1) Gauge Models and Renormalizability
Based on our recent findings regarding (non-)renormalizability of
non-commutative U*(1) gauge theories [arxiv:0908.0467, arxiv:0908.1743] we
present the construction of a new type of model. By introducing a soft breaking
term in such a way that only the bilinear part of the action is modified, no
interaction between the gauge sector and auxiliary fields occurs. Demanding in
addition that the latter form BRST doublet structures, this leads to a
minimally altered non-commutative U*(1) gauge model featuring an IR damping
behavior. Moreover, the new breaking term is shown to provide the necessary
structure in order to absorb the inevitable quadratic IR divergences appearing
at one-loop level in theories of this kind. In the present paper we compute
Feynman rules, symmetries and results for the vacuum polarization together with
the one-loop renormalization of the gauge boson propagator and the three-point
functions.Comment: 20 pages, 4 figures; v2-v4: clarified several points, and minor
correction
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