41 research outputs found
High temperature meson propagators with domain-wall quarks
We study the chiral properties of domain-wall quarks at high temperatures on
an ensemble of quenched configurations. Low lying eigenmodes of the Dirac
operator are calculated and used to check the extent to which the Atiyah-Singer
index theorem is obeyed on lattices with finite . We calculate the
connected and disconnected screening propagators for the lowest mass scalar and
pseudoscalar mesons in the sectors of different topological charge and note
that they behave as expected. Separating out the would-be zero eigenmodes
enables us to accurately estimate the disconnected propagators with far less
effort than would be needed otherwise.Comment: LATTICE99(Finite Temperature and Density), 3 pages, 3 figure
Finite temperature QED3 with light fermions
Non-compact QED3 is simulated both in the quenched and unquenched cases. In
particular, we investigate the restoration of chiral symmetry at finite
temperature. We also compute the zero temperature spectrum of the theory,
including (in the quenched case) the dynamical fermion mass. From these two set
of data, one can obtain estimates for the ratio of the mass gap to the critical
temperature, of particular interest for applications to high-Tc
superconductivity.Comment: talk given at lattice'92, 3 LaTeX pages (using espcrc.sty), figures
available upon reques
Improving the staggered quark action to reduce flavour symmetry violations
We investigate a class of actions for lattice QCD with staggered quarks aimed
at reducing the flavour symmetry violations associated with using staggered
fermions. These actions replace the gauge field link fields in the quark action
with covariantly smeared fields. As such they are an extension of actions
considered by the MILC collaboration. We show that such actions systematically
reduce flavour symmetry violations in the weak coupling limit. Using the mass
splitting between Goldstone and non-Goldstone pions as a measure of flavour
symmetry violations we find that these actions have considerably less flavour
symmetry violations than the standard staggered action, and represent an
improvement on what can be achieved with the MILC action, on quenched
configurations with .Comment: 3 pages, Latex using espcrc2.sty. 1 coloured postscript figure
included with epsffile. Talk presented by D.K.Sinclair at LATTICE'97,
Edinburgh, Scotlan
Thermodynamics of Lattice QCD with massless quarks and chiral 4-fermion interactions
We have simulated lattice QCD with an irrelevant 4-fermion interaction and 2
zero mass quarks. The chiral phase transition is observed to be second order
and we discuss extraction of critical exponents.Comment: LATTICE98(hightemp
QED on a momentum lattice
We investigate the possibility of doing momentum space lattice simulations as
an alternative to the conventional method. The procedure is introduced and
tested for quenched QED2 and quenched QED3. Interesting physical applications
to unquenched QED3 and quenched QED4 are also briefly discussed.Comment: 3 pages, To appear in the proceedings of the LATTICE'93 conference,
ILL-(TH)-93-2
Finite ma corrections for sea quark matrix elements
We discuss the finite corrections associated with the computation of sea
quark matrix elements. We find them to differ from the standard normalization
used for valence quarks and to depend strongly on the Lorentz structure of the
current under consideration. Phenomenological implications of these results are
briefly discussed in two examples. We also mention how the magnitude of the
correction factors can be reduced by using a 2-link improved action.Comment: 3 pages, contribution to LATTICE'94, uuencoded compressed tar file
(square root removed in equation (1)
Manifestations of the axial anomaly in finite temperature QCD
We compute the flavor singlet meson correlators and screening masses in
quenched and QCD at . The consequences of our results for the
realization of the symmetry at finite T are discussed and an
interpretation of our measurements in terms of the behaviour of the low lying
fermionic modes is proposed.Comment: Talk presented at LATTICE96(chirality in QCD
Instantaneous Bethe-Salpeter equation: improved analytical solution
Studying the Bethe-Salpeter formalism for interactions instantaneous in the
rest frame of the bound states described, we show that, for bound-state
constituents of arbitrary masses, the mass of the ground state of a given spin
may be calculated almost entirely analytically with high accuracy, without the
(numerical) diagonalization of the matrix representation obtained by expansion
of the solutions over a suitable set of basis states.Comment: 7 page
Topology, fermionic zero modes and flavor singlet correlators in finite temperature QCD
We extend our earlier results concerning the breaking of the U_A(1) symmetry
in finite temperature QCD. In particular, we use topological arguments to
investigate the chiral limit.Comment: 3 pages, Talk given at LATTICE'9