329 research outputs found
Pauli-Potential and Green Function Monte-Carlo Method for Many-Fermion Systems
The time evolution of a many-fermion system can be described by a Green's
function corresponding to an effective potential, which takes
anti-symmetrization of the wave function into account, called the
Pauli-potential. We show that this idea can be combined with the Green's
Function Monte Carlo method to accurately simulate a system of many
non-relativistic fermions. The method is illustrated by the example of systems
of several (2-9) fermions in a square well.Comment: 12 pages, LaTeX, 4 figure
The heavy-quark pole masses in the Hamiltonian approach
From the fact that the nonperturbative self-energy contribution
to the heavy meson mass is small: ; MeV \cite{ref.01}, strong restrictions on the pole
masses and are obtained. The analysis of the and the
spectra with the use of relativistic (string) Hamiltonian gives
(2-loop) GeV and (2-loop) GeV which
correspond to the running mass GeV and GeV. The masses
and , which define the heavy quarkonia spin structure, are shown to
be by MeV larger than the pole ones.Comment: 18 pages, no figures, 8 table
Yang-Baxter maps and multi-field integrable lattice equations
A variety of Yang-Baxter maps are obtained from integrable multi-field
equations on quad-graphs. A systematic framework for investigating this
connection relies on the symmetry groups of the equations. The method is
applied to lattice equations introduced by Adler and Yamilov and which are
related to the nonlinear superposition formulae for the B\"acklund
transformations of the nonlinear Schr\"odinger system and specific
ferromagnetic models.Comment: 16 pages, 4 figures, corrected versio
On the interrelation between monopoles, vortices, topological charge and chiral symmetry breaking: an analysis using overlap fermions for SU(2)
We study the properties of configurations from which P-vortices on one hand
or Abelian monopoles on the other hand have been removed. We find that the zero
modes and the band of non-zero modes close to zero disappear from the spectrum
of the overlap Dirac operator, confirming the absence of topological charge and
quark condensate. The different behavior of the modified ensembles under
smearing compared to the unmodified Monte Carlo ensemble corroborates these
findings. The gluonic topological susceptibility rapidly approaches zero in
accordance with Q_{index}=0. The remaining (ultraviolet) monopoles without
vortices and -- to a less extent -- the remaining vortices without monopoles
are unstable under smearing whereas smearing of the unmodified Monte Carlo
ensemble effects the monopoles and vortices only by smoothing, reducing the
density only slightly.Comment: 13 pages, 5 figures, strongly revised, results added, one figure
added, accepted for publication, title changed
Effective Monopole Potential for SU(2) Lattice Gluodynamics in Spatial Maximal Abelian Gauge
We investigate the dual superconductor hypothesis in finite-temperature SU(2)
lattice gluodynamics in the Spatial Maximal Abelian gauge. This gauge is more
physical than the ordinary Maximal Abelian gauge due to absence of
non-localities in temporal direction. We show numerically that in the Spatial
Maximal Abelian gauge the probability distribution of the abelian monopole
field is consistent with the dual superconductor mechanism of confinement: the
abelian condensate vanishes in the deconfinement phase and is not zero in the
confinement phase.Comment: LaTeX2e, 8 pages with 3 EPS figures, uses epsf.st
Higgs Boson Sector of the Next-to-MSSM with CP Violation
We perform a comprehensive study of the Higgs sector in the framework of the
next-to-minimal supersymmetric standard model with CP-violating parameters in
the superpotential and in the soft-supersymmetry-breaking sector. Since the CP
is no longer a good symmetry, the two CP-odd and the three CP-even Higgs bosons
of the next-to-minimal supersymmetric standard model in the CP-conserving limit
will mix. We show explicitly how the mass spectrum and couplings to gauge
bosons of the various Higgs bosons change when the CP-violating phases take on
nonzero values. We include full one-loop and the logarithmically enhanced
two-loop effects employing the renormalization-group (RG) improved approach. In
addition, the LEP limits, the global minimum condition, and the positivity of
the square of the Higgs-boson mass have been imposed. We demonstrate the
effects on the Higgs-mass spectrum and the couplings to gauge bosons with and
without the RG-improved corrections. Substantial modifications to the allowed
parameter space happen because of the changes to the Higgs-boson spectrum and
their couplings with the RG-improved corrections. Finally, we calculate the
mass spectrum and couplings of the few selected scenarios and compare to the
previous results in literature where possible; in particular, we illustrate a
scenario motivated by electroweak baryogenesis.Comment: 40 pages, 49 figures; v2: typos corrected and references added; v3:
some clarification and new figures added, version published in PR
Some properties of the k-dimensional Lyness' map
This paper is devoted to study some properties of the k-dimensional Lyness'
map. Our main result presentes a rational vector field that gives a Lie
symmetry for F. This vector field is used, for k less or equal to 5 to give
information about the nature of the invariant sets under F. When k is odd, we
also present a new (as far as we know) first integral for F^2 which allows to
deduce in a very simple way several properties of the dynamical system
generated by F. In particular for this case we prove that, except on a given
codimension one algebraic set, none of the positive initial conditions can be a
periodic point of odd period.Comment: 22 pages; 3 figure
Casimir eigenvalues for universal Lie algebra
For two different natural definitions of Casimir operators for simple Lie
algebras we show that their eigenvalues in the adjoint representation can be
expressed polynomially in the universal Vogel's parameters and give explicit formulae for the generating functions of these
eigenvalues.Comment: Slightly revised versio
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