2,364 research outputs found
Hamiltonian approach to Yang-Mills theory in Coulomb gauge
Recent results obtained within the Hamiltonian approach to continuum
Yang-Mills theory in Coulomb gauge are reviewed.Comment: 7 pages, 2 figures, to appear in the ``Quark Confinement and the
hadron spectrum VII'' (Portugal 2006) conference proceeding
Confining Solution of the Dyson-Schwinger Equations in Coulomb Gauge
The Dyson-Schwinger equations arising from minimizing the vacuum energy
density in the Hamiltonian approach to Yang-Mills theory in Coulomb gauge are
solved numerically. A new solution is presented which gives rise to a strictly
linearly rising static quark potential and whose existence was previously
observed in the infrared analysis of the Dyson-Schwinger equations. For the new
solution we also present the static quark potential and calculate the running
coupling constant from the ghost-gluon vertex.Comment: 9 pages, 3 figures, references added
Equal-time two-point correlation functions in Coulomb gauge Yang-Mills theory
We apply a functional perturbative approach to the calculation of the
equal-time two-point correlation functions and the potential between static
color charges to one-loop order in Coulomb gauge Yang-Mills theory. The
functional approach proceeds through a solution of the Schroedinger equation
for the vacuum wave functional to order g^2 and derives the equal-time
correlation functions from a functional integral representation via new
diagrammatic rules. We show that the results coincide with those obtained from
the usual Lagrangian functional integral approach, extract the beta function,
and determine the anomalous dimensions of the equal-time gluon and ghost
two-point functions and the static potential under the assumption of
multiplicative renormalizability to all orders.Comment: 33 pages, 7 figures with Feyman diagrams generated with pstricks;
revised version with additional references and comments on possible
applications added in the conclusions; accepted for publication in Nucl.
Phys.
Electromagnetic Calorimeter for HADES
We propose to build the Electromagnetic calorimeter for the HADES di-lepton
spectrometer. It will enable to measure the data on neutral meson production
from nucleus-nucleus collisions, which are essential for interpretation of
dilepton data, but are unknown in the energy range of planned experiments (2-10
GeV per nucleon). The calorimeter will improve the electron-hadron separation,
and will be used for detection of photons from strange resonances in elementary
and HI reactions.
Detailed description of the detector layout, the support structure, the
electronic readout and its performance studied via Monte Carlo simulations and
series of dedicated test experiments is presented.
The device will cover the total area of about 8 m^2 at polar angles between
12 and 45 degrees with almost full azimuthal coverage. The photon and electron
energy resolution achieved in test experiments amounts to 5-6%/sqrt(E[GeV])
which is sufficient for the eta meson reconstruction with S/B ratio of 0.4% in
Ni+Ni collisions at 8 AGeV. A purity of the identified leptons after the hadron
rejection, resulting from simulations based on the test measurements, is better
than 80% at momenta above 500 MeV/c, where time-of-flight cannot be used.Comment: 40 pages, 38 figures version2 - the time schedule added, information
about PMTs in Sec.III update
Truncating first-order Dyson-Schwinger equations in Coulomb-Gauge Yang-Mills theory
The non-perturbative domain of QCD contains confinement, chiral symmetry
breaking, and the bound state spectrum. For the calculation of the latter, the
Coulomb gauge is particularly well-suited. Access to these non-perturbative
properties should be possible by means of the Green's functions. However,
Coulomb gauge is also very involved, and thus hard to tackle. We introduce a
novel BRST-type operator r, and show that the left-hand side of Gauss' law is
r-exact.
We investigate a possible truncation scheme of the Dyson-Schwinger equations
in first-order formalism for the propagators based on an instantaneous
approximation. We demonstrate that this is insufficient to obtain solutions
with the expected property of a linear-rising Coulomb potential. We also show
systematically that a class of possible vertex dressings does not change this
result.Comment: 22 pages, 4 figures, 1 tabl
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