472 research outputs found
Fermions from photons: Bosonization of QED in 2+1 dimensions
We perform the complete bosonization of 2+1 dimensional QED with one
fermionic flavor in the Hamiltonian formalism. The Fermi operators are
explicitly constructed in terms of the vector potential and the electric field.
We carefully specify the regularization procedure involved in the definition of
these operators, and calculate the fermionic bilinears and the energy -
momentum tensor. The algebra of bilinears exhibits the Schwinger terms which
also appear in perturbation theory. The bosonic Hamiltonian is a local,
polynomial functional of and , and we check explicitly the Lorentz
invariance of the resulting bosonic theory. Our construction is conceptually
very similar to Mandelstam's construction in 1+1 dimensions, and is dissimilar
from the recent bosonization attempts in 2+1 dimensions, which hinge crucially
on the presence of a Chern - Simons term.Comment: 30 pages, LA - UR - 93 - 200
From bubbles to foam: dilute to dense evolution of hadronic wave function at high energy
We derive the evolution of a hadronic light cone wave function with energy at
weak coupling. Our derivation is valid both in the high and the low partonic
density limit, and thus encompasses both the JIMWLK and the KLWMIJ evolution.
The hadronic wave function is shown to evolve by the action of the
Bogoliubov-type operator, which diagonalizes on the soft gluon sector the
light-cone hamiltonian in the presence of an arbitrary valence charge density.
We find explicitly the action of this operator on the soft as well as the
valence degrees of freedom of the theory.Comment: 30 page
Vortices and bags in 2+1 dimension
We consider the effect of the (heavy) fundamental quarks on the low energy
effective Lagrangian description of nonabelian gauge theories in 2+1
dimensions. We show that in the presence of the fundamental charges, the
magnetic symmetry becomes local. We construct the effective Lagrangian
representing this local symmetry in terms of magnetic vortex fields, and
discuss its physical consequences. We show that the finite energy states
described by this Lagrangian have distinct bag-like structure. The point-like
quarks are confined to the region of space where the value of the vortex field
is much smaller than in the surrounding vacuum.Comment: 26 pages, laTe
The chicken or the egg; or Who ordered the chiral phase transition?
We draw an analogy between the deconfining transition in the 2+1 dimensional
Georgi-Glashow model and the chiral phase transition in 3+1 dimensional QCD.
Based on the detailed analysis of the former (hep-th/0010201) we suggest that
the chiral symmetry restoration in QCD at high temperature is driven by the
thermal ensemble of baryons and anti-baryons. The chiral symmetry is restored
when roughly half of the volume is occupied by the baryons. Surprisingly
enough, even though baryons are rather heavy, a crude estimate for the critical
temperature gives Mev. In this scenario the binding of the instantons
is not the cause but rather a consequence of the chiral symmetry restoration.Comment: 22 pages, 7 figures, comments about chiral symmetry at finite nuclear
density are adde
Critical Exponents of the Superconducting Phase Transition
We study the critical exponents of the superconducting phase transition in
the context of renormalization group theory starting from a dual formulation of
the Ginzburg-Landau theory. The dual formulation describes a loop gas of
Abrikosov flux tubes which proliferate when the critical temperature is
approached from below. In contrast to the Ginzburg-Landau theory, it has a
spontaneously broken global symmetry and possesses an infrared stable fixed
point. The exponents coincide with those of a superfluid with reversed
temperature axis.Comment: Postscript file. For related work see www adress
http://www.physik.fu-berlin.de/kleiner_re.html in our homepage
http://www.physik.fu-berlin.de/kleinert.htm
U_A(1) Anomaly at high temperature: the scalar-pseudoscalar splitting in QCD
We estimate the splitting between the spatial correlation lengths in the
scalar and pseudoscalar channels in QCD at high temperature. The splitting is
due to the contribution of the instanton/anti-instanton chains in the thermal
ensemble, even though instanton contributions to thermodynamic quantities are
suppressed. The splitting vanishes at asymptotically high temperatures as
, where is the beta function
coefficient.Comment: 5 p
An analytic study towards instabilities of the glasma
Strong longitudinal color flux fields will be created in the initial stage of
high-energy nuclear collisions. We investigate analytically time evolution of
such boost-invariant color fields from Abelian-like initial conditions, and
next examine stability of the boost-invariant configurations against rapidity
dependent fluctuations. We find that the magnetic background field has an
instability induced by the lowest Landau level whose amplitude grows
exponentially. For the electric background field there is no apparent
instability although pair creations due to the Schwinger mechanism should be
involved.Comment: 4p, 3figs; poster contribution to QM200
Compact QED - a simple example of a variational calculation in a gauge theory
We apply a simple mean field like variational calculation to compact QED in
2+1 dimensions. Our variational ansatz explicitly preserves compact gauge
invariance of the theory. We reproduce in this framework all the known results,
including dynamical mass generation, Polyakov scaling and the nonzero string
tension. It is hoped that this simple example can be a useful reference point
for applying similar approximation techniques to nonabelian gauge theories.Comment: 18 pages, OUTP- 94-23 P, TPI-MINN-94/37-
Relativistic Winds from Compact Gamma-Ray Sources: II. Pair Loading and Radiative Acceleration in Gamma-ray Bursts
We consider the effects of rapid pair creation by an intense pulse of
gamma-rays propagating ahead of a relativistic shock. Side-scattered photons
colliding with the main gamma-ray beam amplify the density of scattering
charges. The acceleration rate of the pair-loaded medium is calculated, and its
limiting bulk Lorentz factor related to the spectrum and compactness of the
photon source. One obtains, as a result, a definite prediction for the relative
inertia in baryons and pairs. The deceleration of a relativistic shock in the
moving medium, and the resulting synchrotron emissivity, are compared with
existing calculations for a static medium. The radiative efficiency is
increased dramatically by pair loading. When the initial ambient density
exceeds a critical value, the scattering depth traversed by the main gamma-ray
pulse rises above unity, and the pulse is broadened. These considerations place
significant constraints on burst progenitors: a pre-burst mass loss rate
exceeding 10^{-5} M_\odot per year is difficult to reconcile with individual
pulses narrower than 10 s, unless the radiative efficiency is low. An
anisotropic gamma-ray flux (on an angular scale \Gamma^{-1} or larger) drives a
large velocity shear that greatly increases the energy in the seed magnetic
field forward of the propagating shock.Comment: 19 pp., LaTeX (aaspp4.sty), revised 12/23/99, Ap. J. in press;
summary section added and several minor improvements in presentatio
Supersymmetric Yang-Mills theory on the lattice
Recent development in numerical simulations of supersymmetric Yang-Mills
(SYM) theories on the lattice is reviewed.Comment: 37 pages, 10 figure
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