73 research outputs found
Non-perturbative renormalisation for overlap fermions
Using non-perturbative techniques we have found the renormalisation factor,
Z, in the RI-MOM scheme for quark bilinear operators in quenched QCD. We worked
with overlap fermions using the Luescher-Weisz gauge action. Our calculation
was performed at beta=8.45 at a lattice spacing of 1/a=2.1 GeV using a value of
rho=1.4. Our results show good agreement between the vector and the axial
vector in the zero mass limit. This shows that overlap fermions have good
chiral properties. To attempt to improve the discretisation errors in our
results we subtracted the O(a^2) terms in one-loop lattice perturbation theory
from the Monte Carlo Green functions. In particular we paid attention to the
operators for the observable . We found a value for the renormalisation
constants Z^msbar_(v_2b) and Z^msbar_(v_2a) just less than 1.9 at mu=1/a=2.1
GeV.Comment: 6 pages, 3 figures, uses PoS style, poster presented at Lattice 2005
(Chiral Fermions), to be published in Proceedings of Scienc
A lattice determination of g_A and <x> from overlap fermions
We present results for the nucleon's axial charge g_A and the first moment
of the unpolarized parton distribution function from a simulation of
quenched overlap fermions.Comment: Talk presented at Lattice2004(chiral), 4 pages, 4 figure
Baryonic Flux in Quenched and Two-Flavor Dynamical QCD after Abelian projection
We study the distribution of color electric flux of the three-quark system in
quenched and full QCD (with N_f = 2 flavors of dynamical quarks) at zero and
finite temperature. To reduce ultra-violet fluctuations, the calculations are
done in the abelian projected theory fixed to the maximally abelian gauge. In
the confined phase we find clear evidence for a Y--shape flux tube surrounded
and formed by the solenoidal monopole current, in accordance with the dual
superconductor picture of confinement. In the deconfined, high temperature
phase monopoles cease to condense, and the distribution of the color electric
field becomes Coulomb--like.Comment: 21 pages, 15 figures, Latex, published version (4 figures added
Flux Tubes of Two- and Three-Quark System in Full QCD
We study the abelian color flux of two- and three-quark systems in the
maximally abelian gauge in lattice QCD with dynamical fermions. We find that
the abelian flux tube formed between quark and antiquark is very much the same
as in quenched QCD up to quark separations of 2fm. The profile of the
color electric field in three-quark system suggests ansatz, which might be
interpreted as the result of the vacuum pressure in the confined phase. In
order to clarify the flux structure, we investigate the color electric field of
the three-quark system splittting the abelian gauge field into the monopole and
photon parts.Comment: 4 pages, 4 figures, Talk given at XVI International Conference on
Particles and Nuclei (PaNic02),Osaka, Japan, Sep.30 - Oct.4, 200
The flux distribution of the three quark system in SU(3)
We study the abelian color-flux distribution of the three quark system in the
maximally abelian gauge on SU(3) lattices. The distribution of the color
electric field suggests , which might be interpreted through the dual
superconductor picture as the result of the vacuum pressure in the confined
phase. In order to clarify the flux structure, we investigate the color
electric field in the three quark system also in the monopole part and in the
photon part.Comment: 3pages, 5figures, Lattice2002(topology
- …