15,862 research outputs found
Finite Temperature Phase Diagramm of QCD with improved Wilson fermions
We present first results of a study of two flavour QCD with Wilson fermions
at finite temperature. We have used tree level Symanzik improvement in both the
gauge and fermion part of the action. In a first step we explore the phase
diagramm on an lattice, with particular emphasis on checking
Aoki's conjecture with an improved action.Comment: Talk presented at LATTICE97(finite temperature), 3 pages, 3
Postscript figure
The end point of the first-order phase transition of the SU(2) gauge-Higgs model on a four-dimensional isotropic lattice
We report results of a study of the end point of the electroweak phase
transition of the SU(2) gauge-Higgs model defined on a four-dimensional
isotropic lattice with N_t=2. Finite-size scaling study of Lee-Yang zeros
yields lambda_c=0.00116(16) for the end point. Combined with a zero-temperature
measurement of Higgs and W boson masses, this leads to M_{H,c}=68.2+-6.6 GeV
for the critical Higgs boson mass. An independent analysis of Binder cumulant
gives a consistent value lambda_c=0.00102(3) for the end point.Comment: LATTICE98(electroweak), 3 pages of LaTeX, 4 figure
Universality in the Gross-Neveu model
We consider universal finite size effects in the large-N limit of the
continuum Gross-Neveu model as well as in its discretized versions with Wilson
and with staggered fermions. After extrapolation to zero lattice spacing the
lattice results are compared to the continuum values.Comment: Lattice2004(theory
Green's Function for Nonlocal Potentials
The single-particle nuclear potential is intrinsically nonlocal. In this
paper, we consider nonlocalities which arise from the many-body and fermionic
nature of the nucleus. We investigate the effects of nonlocality in the nuclear
potential by developing the Green's function for nonlocal potentials. The
formal Green's function integral is solved analytically in two different limits
of the wavelength as compared to the scale of nonlocality. Both results are
studied in a quasi-free limit. The results illuminate some of the basic effects
of nonlocality in the nuclear medium.Comment: Accepted for publication in J. Phys.
Perturbative study for domain-wall fermions in 4+1 dimensions
We investigate a U(1) chiral gauge model in 4+1 dimensions formulated on the
lattice via the domain-wall method. We calculate an effective action for smooth
background gauge fields at a fermion one loop level. From this calculation we
discuss properties of the resulting 4 dimensional theory, such as gauge
invariance of 2 point functions, gauge anomalies and an anomaly in the fermion
number current.Comment: 39 pages incl. 9 figures, REVTeX+epsf, uuencoded Z-compressed .tar
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Multidecadal warming of Antarctic waters
Decadal trends in the properties of seawater adjacent to Antarctica are poorly known, and the mechanisms responsible for such changes are uncertain. Antarctic ice sheet mass loss is largely driven by ice shelf basal melt, which is influenced by ocean-ice interactions and has been correlated with Antarctic Continental Shelf Bottom Water (ASBW) temperature. We document the spatial distribution of long-term large-scale trends in temperature, salinity, and core depth over the Antarctic continental shelf and slope. Warming at the seabed in the Bellingshausen and Amundsen seas is linked to increased heat content and to a shoaling of the mid-depth temperature maximum over the continental slope, allowing warmer, saltier water greater access to the shelf in recent years. Regions of ASBW warming are those exhibiting increased ice shelf melt
Phase structure and critical temperature of two-flavor QCD with a renormalization group improved gauge action and clover improved Wilson quark action
We study the finite-temperature phase structure and the transition
temperature of QCD with two flavors of dynamical quarks on a lattice with the
temporal size , using a renormalization group improved gauge action and
the Wilson quark action improved by the clover term. The region of a
parity-broken phase is identified, and the finite-temperature transition line
is located on a two-dimensional parameter space of the coupling ()
and hopping parameter . Near the chiral transition point, defined as the
crossing point of the critical line of the vanishing pion mass and the line of
finite-temperature transition, the system exhibits behavior well described by
the scaling exponents of the three-dimensional O(4) spin model. This indicates
a second-order chiral transition in the continuum limit. The transition
temperature in the chiral limit is estimated to be MeV.Comment: Typographical errors fixed. RevTeX, 19 pages, 17 PS figure
Neutron Electric Dipole Moment with Domain Wall Quarks
We present preliminary results for nucleon dipole moments computed with
domain wall fermions. Our main target is the electric dipole moment of the
neutron arising from the theta term in the gauge part of the QCD lagrangian.
The calculated magnetic dipole moments of the proton and neutron are in rough
accord with experimental values.Comment: 3 pages. Contribution to the proceedings of Lattice 2004 (Fermilab
Lattice study of the Coleman--Weinberg mass in the SU(2)-Higgs model
Radiative symmetry breaking is a well known phenomenon in perturbation
theory. We study the problem in a non-perturbative framework, i.e. lattice
simulations. The example of the bosonic sector of the SU(2)-Higgs model is
considered. We determine the minimal scalar mass which turns out to be higher
than the mass value given by 1-loop continuum perturbation theory.Comment: Contribution to ICHEP-02, Amsterdam, 24-31 July 2002, 2 pages, 1
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