121 research outputs found
Magnetic Monopoles in non-compact QED - is there a Phase Transition?
The existence of the monopole condensation transition reported by
Kocic et al. in non-compact, quenched QED is tested. No phase transition is
found. This shows that divergence of the `monopole susceptibility' introduced
by Hands and Wensley is not a reliable indicator of second order phase
transitions. In view of these results
I discuss claims that the chiral phase transition seen in QED with fermions
is a lattice artefact driven by monopole condensation.Comment: Talk given at lattice '92, 4 pages, uses espcrc2.sty, 2 postscript
figures attached. (Replaced to add the figures.) Preprint FUB-HEP 22/9
Probing the Continuum Limit in Non-Compact QED: New Results on Large Lattices
We present new Monte Carlo results in non-compact lattice QED with staggered
fermions down to m_0 = 0.005. This extends our previous investigations on the
nature of the continuum limit of QED.Comment: 7 pages, uuencoded compressed PostScript, also available at
ftp://ftp.zib-berlin.de/pub/zib-publications/Reports/SC-94-31.ps.
Operator improvement for Ginsparg-Wilson fermions
The improvement of fermionic operators for Ginsparg-Wilson fermions is
investigated. We present explicit formulae for improved Green's functions,
which apply both on-shell and off-shell.Comment: 13 pages, Latex, 4 postscript figure
The present status of non-compact lattice QED
We give a 1993 update of non-compact lattice QED, in particular the chiral
condensate, finite size effects and meson mass ratios.
We compare descriptions of the phase transition. Our previous conclusions
remain valid.Comment: Poster presentation at LAT93, Dallas, U.S.A. Postscript file, 4
pages, figures included. Preprint numbers DESY-93-178, FUB-HEP/93-20 and HLRZ
93-7
Vacuum polarisation and the muon g-2 in lattice QCD
We measure the hadronic contribution to the vacuum polarisation tensor, and
use it to estimate the hadronic contribution to (g-2)_mu, the muon anomalous
magnetic moment.Comment: 3 pages, 4 figures, Latex. Talk given by P.E.L. Rakow at
Lattice2003(matrix
The Nambu-Jona-Lasinio model with staggered fermions
We investigate the neighbourhood of the chiral phase transition in a lattice
Nambu--Jona-Lasinio model, using both Monte Carlo methods and lattice
Schwinger-Dyson equations.Comment: Talks at LAT93, Dallas, U.S.A. Postscript file, 6 pages, figures
include
Three-point functions in noncompact lattice QED
We calculate fermion-antifermion-"meson" three-point functions in noncompact
lattice QED with dynamical staggered fermions and use them to extract effective
Yukawa couplings. The results are consistent with the hypothesis that QED is
trivial.Comment: Latex article. 3 pages, ps file. Contribution to LAT93, Dallas,
U.S.A. HLRZ preprint 93-7
Lattice QCD at finite temperature: Evidence for calorons from the eigenvectors of the Dirac operator
We analyze the eigenvalues and eigenvectors of the staggered Dirac operator
in quenched lattice QCD in the vicinity of the deconfinement phase transition
using the L\"uscher-Weisz gauge action. The spectral and localization
properties of the low-lying eigenmodes show characteristic differences between
the Z_3 sectors above the critical temperature T_c. These findings can be
interpreted in terms of calorons.Comment: Lattice2001(hightemp), 3 pages, 2 figure
The spin structure of the Lambda hyperon in quenched lattice QCD
It has been suggested to use the production of Lambda hyperons for
investigating the nucleon spin structure. The viability of this idea depends
crucially on the spin structure of the Lambda. Using nonperturbatively O(a)
improved Wilson fermions in the quenched approximation we have studied matrix
elements of two-quark operators in the Lambda. We present results for the axial
vector current, which give us the contributions of the u, d, and s quarks to
the Lambda spin.Comment: Lattice2001(matrixelement), 3 pages, 2 figure
One-loop renormalisation for the second moment of GPDs with Wilson fermions
We calculate the non-forward quark matrix elements for operators with two
covariant derivatives in one-loop lattice perturbation theory using Wilson
fermions. These matrix elements are needed in the renormalisation of the second
moment of generalised parton distributions measured in lattice QCD. For some
commonly used representations of the hypercubic group we determine the sets of
all mixing operators and find the matrices of mixing and renormalisation
factors.Comment: Lattice 2004(improved), 3 pages, LaTeX style file, espcrc2.sty
include
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