639 research outputs found
Detailed Phase Transition Study at M_H <= 70 GeV in a 3-dimensional --Higgs Model
We study the electroweak phase transition in an effective 3-dimensional
theory for a Higgs mass of about 70 GeV by Monte Carlo simulations. The
transition temperature and jumps of order parameters are obtained and
extrapolated to the continuum using multi-histogram techniques and finite size
analysis.Comment: Talk presented at LATTICE96(electroweak), 4 pages, 5 figure
Locality with staggered fermions
We address the locality problem arising in simulations, which take the square
root of the staggered fermion determinant as a Boltzmann weight to reduce the
number of dynamical quark tastes. A definition of such a theory necessitates an
underlying local fermion operator with the same determinant and the
corresponding Green's functions to establish causality and unitarity. We
illustrate this point by studying analytically and numerically the square root
of the staggered fermion operator. Although it has the correct weight, this
operator is non-local in the continuum limit. Our work serves as a warning that
fundamental properties of field theories might be violated when employing
blindly the square root trick. The question, whether a local operator
reproducing the square root of the staggered fermion determinant exists, is
left open.Comment: 24 pages, 7 figures, few remarks added for clarity, accepted for
publication in Nucl. Phys.
The locality problem for two tastes of staggered fermions
We address the locality problem arising in simulations, which take the square
root of the staggered fermion determinant as a Boltzmann weight to reduce the
number of dynamical quark tastes from four to two. We study analytically and
numerically the square root of the staggered fermion operator as a candidate to
define a two taste theory from first principles. Although it has the correct
weight, this operator is non-local in the continuum limit. Our work serves as a
warning that fundamental properties of field theories might be violated when
employing blindly the square root trick. The question, whether a local operator
reproducing the square root of the staggered fermion determinant exists, is
left open.Comment: Talk presented at Lattice2004(theory), Fermilab, June 21-26, 200
Results from 3D Electroweak Phase Transition Simulations
We study the phase transition in SU(2)-Higgs model on the lattice using the
3D dimensionally reduced formalism. The 3D formalism enables us to obtain
highly accurate Monte Carlo results, which we extrapolate both to the infinite
volume and to the continuum limit. Our formalism also provides for a
well-determined and unique way to relate the results to the perturbation
theory. We measure the critical temperature, latent heat and interface tension
for Higgs masses up to 70 GeV.Comment: 4 pages uuencoded postscript, contribution to LATTICE 9
Physics of the Electroweak Phase Transition at M_H <= 70 GeV in a 3-dimensional SU(2)-Higgs Model
Physical parameters of the electroweak phase transition in a 3d effective
lattice SU(2)-Higgs model are presented. The phase transition temperatures,
latent heats and continuum condensate discontinuities are measured at Higgs
masses of about 70 and 35 GeV. Masses and Higgs condensates are compared to
perturbation theory in the broken phase. In the symmetric phase bound states
and the static force are determined.Comment: Talk presented at LATTICE96(electroweak), 4 pages, 5 figure
A 0-dimensional counter-example to rooting?
We provide an example of a 0-dimensional field theory where rooting does not
work.Comment: 3 pages; Physics Letters B (2010
A Study of Practical Implementations of the Overlap-Dirac Operator in Four Dimensions
We study three practical implementations of the Overlap-Dirac operator in four dimensions. Two implementations are
based on different representations of as a sum over poles. One
of them is a polar decomposition and the other is an optimal fit to a ratio of
polynomials. The third one is obtained by representing using
Gegenbauer polynomials and is referred to as the fractional inverse method.
After presenting some spectral properties of the Hermitian operator
, we study its spectrum in a smooth SU(2) instanton
background with the aim of comparing the three implementations of . We
also present some results in SU(2) gauge field backgrounds generated at
on an lattice. Chiral properties have been numerically
verified.Comment: 23 pages latex with 9 postscript figures included by epsf. Some
change in referencing and one figure modifie
Four-dimensional Simulation of the Hot Electroweak Phase Transition with the SU(2) Gauge-Higgs Model
We study the finite-temperature phase transition of the four-dimensional
SU(2) gauge-Higgs model for intermediate values of the Higgs boson mass in the
range 50 \lsim m_H \lsim 100GeV on a lattice with the temporal lattice size
. The order of the transition is systematically examined using finite
size scaling methods. Behavior of the interface tension and the latent heat for
an increasing Higgs boson mass is also investigated.Comment: Talk presented at LATTICE96(electroweak), 3 pages of LaTeX, 4
PostScript figure
3d physics and the electroweak phase transition: a framework for lattice Monte Carlo analysis
We discuss a framework relying on both perturbative and non-perturbative
lattice computations which will be able to reliably determine the parameters of
the EW phase transition. A motivation for the use of 3d effective theory in the
lattice simulations, rather than the complete 4d one, is provided. We introduce
and compute on the 2-loop level a number of gauge-invariant order parameters --
condensates, which can be measured with high accuracy in MC simulations. The
relation between MSbar and lattice condensates is found, together with the
relation between lattice couplings and continuum parameters (the constant
physics curves). These relations are exact in the continuum limit.Comment: 50 pages, uuencoded compressed postscript fil
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