title:
Probing the chiral limit of M_pi and f_pi in 2+1 flavor QCD with domain
  wall fermions from QCDOC

abstract:
  We present results for the pseudoscalar meson masses and decay constants on
2+1 flavor DWF configurations with different sea quark masses and an inverse
lattice spacing of 1.6(1) GeV, with a focus on chiral fits at small quark
masses. The calculation is done on 16^3x32x8 lattices generated with the DBW2
gauge action.


title: Combining Quark and Link Smearing to Improve Extended Baryon Operators

abstract:
  The effects of Gaussian quark-field smearing and analytic stout-link smearing
on the correlations of gauge-invariant extended baryon operators are studied.
Gaussian quark-field smearing substantially reduces contributions from the
short wavelength modes of the theory, while stout-link smearing significantly
reduces the noise from the stochastic evaluations. The use of gauge-link
smearing is shown to be crucial for baryon operators constructed of
covariantly-displaced quark fields. Preferred smearing parameters are
determined for a lattice spacing a_s ~ 0.1 fm.


title: Lattice QCD at Finite Temperature and Density

abstract:
  A general introduction into the subject aimed at a general theoretical
physics audience. We introduce the sign problem posed by finite density lattice
QCD, and we discuss the main methods proposed to circumvent it, with emphasis
on the imaginary chemical potential approach. The interrelation between the
Taylor expansion and the analytic continuation from imaginary chemical
potential is discussed in detail. The main applications to the calculation of
the critical line, and to the thermodynamics of the hot and the hadronic phase
are reviewed.


title:
Series representation; Pade' approximants and critical behavior in QCD
  at nonzero T and $mu_B$

abstract:
  We discuss the analytic continuation beyond $\mu/T \simeq 1$ in QCD at
nonzero T and $\mu$ by use of the Pade' approximants. The slope of the critical
line obtained in this way increases at large $\mu$ with respect to the second
order Taylor result.In the hot phase Pade' and Taylor approximants coincide,
suggesting a very large, and possibly infinite, radius of convergence of the
Taylor series in this thermodynamic region.


title: Light hadron spectroscopy in quenched QCD with overlap fermions

abstract:
  A simulation of quenched QCD with the overlap Dirac operator has been carried
out using 100 Wilson gauge configurations at beta = 6 on an 18^3 x 64 lattice
and at beta = 5.85 on a 14^3 x 48 lattice. Here we present results for meson
masses, meson final state "wave functions," decay constants, and other
observables, as well as details on our algorithmic and data analysis
techniques. We also summarize results for baryon masses and quark and diquark
propagators in the Landau gauge.


title:
QED_3 on a space-time lattice: a comparison between compact and
  noncompact formulation

abstract:
  Quantum electrodynamics in a (2+1)-dimensional space-time has been object of
studies both as effective theory for the pseudogap phase of high-T_c
superconductors and for the theoretical investigation of mechanisms of
confinement in presence of matter fields. We discretize the theory using both
compact and noncompact formulations, analyze the behavior of the chiral
condensate and of the monopole density and compare them. Finally we draw some
conclusions about the possible equivalence of the two lattice formulations.


title:
Parameter dependence of the topology change and the scaling properties
  of the topology conserving gauge action

abstract:
  The topology conserving gauge action proposed by Luescher is expected to
reduce the number of non-smooth gauge configurations as well as the topology
change compared to the conventional actions for the same lattice spacings. We
report our quenched QCD study of the topological stability and the scaling
violation of the static quark potential. We find that the the topology change
is indeed suppressed when the parameter epsilon is of order one. We also find
that the scaling violation in the static quark potential remain reasonably
small in the parameter range of our study. Our study is done at the inverse
lattice spacing a^{-1}=1.4-2.5 GeV with the lattice size L=1.0-1.6fm.


title: Hadron structure with light dynamical quarks

abstract:
  Generalized parton distributions encompass a wealth of information concerning
the three-dimensional quark and gluon structure of the nucleon, and thus
provide an ideal focus for the study of hadron structure using lattice QCD. The
special limits corresponding to form factors and parton distributions are well
explored experimentally, providing clear tests of lattice calculations, and the
lack of experimental data for more general cases provides opportunities for
genuine predictions and for guiding experiment. We present results from hybrid
calculations with improved staggered (Asqtad) sea quarks and domain wall
valence quarks at pion masses down to 350 MeV.


title: The pressure and a possible hidden Hagedorn transition at large-N

abstract:
  In the first part of this contribution we present a numerical study motivated
by recent attempts to understand the nonperturbative aspects of QCD at
temperatures T~ a few times the deconfinement temperature Tc. We focus on the
pure gauge theory, and ask whether the deficit in pressure and entropy, with
respect to their free-gas values, is particular to SU(3). We find that the
deficit in SU(4),SU(8) for T>= 2Tc,1.6 Tc, respectively, is remarkably close to
that of SU(3). This suggests a similar deficit for SU(oo), which is fortunate
since this theory is simpler, and can serve to constrain the possible dynamics
underlying the deficits.
  In the second part we seek for signs of a Hagedorn temperature T_H in pure
lattice SU(N) gauge theories with N=8,10,12. Since one expects T_H>Tc, we
measure masses of strings in the metastable confined phase above Tc, and
extrapolatethem to zero to estimate T_H. For SU(12) we find that
T_H/Tc=1.116(9), when we extrapolate with a critical exponentof the three
dimensional XY model, which seems to be preferred over a mean field exponent by
our data.


title:
Applying Groebner Bases to Solve Reduction Problems for Feynman
  Integrals

abstract:
  We describe how Groebner bases can be used to solve the reduction problem for
Feynman integrals, i.e. to construct an algorithm that provides the possibility
to express a Feynman integral of a given family as a linear combination of some
master integrals. Our approach is based on a generalized Buchberger algorithm
for constructing Groebner-type bases associated with polynomials of shift
operators. We illustrate it through various examples of reduction problems for
families of one- and two-loop Feynman integrals. We also solve the reduction
problem for a family of integrals contributing to the three-loop static quark
potential.


title: Dynamical determination of B_K from improved staggered quarks

abstract:
  The scaling corrections that affected previous staggered calculations of B_K
have been proved to be reduced by using improved actions (HYP, Asqtad) in the
quenched approximation. This improved behaviour allows us to perform a reliable
dynamical calculation of B_K including quark vacuum polarization effects using
the MILC (2+1) flavour dynamical configurations. We report here on the results
from such dynamical calculation. We also discuss the renormalization effects
with the Asqtad action.


title: Low-energy J/psi-Hadron Interactions from Quenched Lattice QCD

abstract:
  The J/psi-hadron interaction is a key ingredient in analyzing the J/psi
suppression in hot hadronic matter as well as the propagation of J/psi in
nuclei. As a first step to clarify the J/psi-hadron interactions at low
energies, we have calculated J/psi-pi, J/psi-rho and J/psi-nucleon scattering
lengths by the quenched lattice QCD simulations with Wilson fermions for
beta=6.2 on 24^3*48 and 32^3*48 lattices. Using the Luscher's method to extract
the scattering length from the simulations in a finite box, we find an
attractive interaction in the S-wave channel for all three systems: Among
others, the J/psi-nucleon interaction is most attractive. Possibility of the
J/psi-nucleon bound state is also discussed.


title: Double poles in Lattice QCD with mixed actions

abstract:
  We consider effects resulting from the use of different discretizations for
the valence and the sea quarks, considering Wilson and/or Ginsparg--Wilson
fermions. We assume that such effects appear through scaling violations that
can be studied using effective-lagrangian techniques. We show that a double
pole is present in flavor-neutral Goldstone meson propagators, even if the
flavor non-diagonal Goldstone mesons made out of valence or sea quark have
equal masses. We then consider some observables known to be anomalously
sensitive to the presence of a double pole. We find that the double-pole
enhanced scaling violations may turn out to be rather small in practice.


title:
Dimensional regularization of Schrodinger Functional correlation
  functions

abstract:
  The matching between Schrodinger Functional renormalization schemes and
conventional perturbative schemes is usually done using an intermediate lattice
scheme. We propose to do the matching directly. This requires the perturbative
evaluation of Schrodinger Functional correlation functions in the continuum. We
use dimensional regularization but due to the lack of translational invariance
in the Euclidean time direction, we employ a general technique introduced by
Luscher. In this talk I describe this technique and its application to the
one-loop expansion of correlation functions used in the definition of the
renormalized quark mass in the Schrodinger Functional scheme. The divergent
parts are identified and the computation of finite parts is in progress.


title: Critical Behaviour in Statistical QCD

abstract:
  We survey the critical behaviour of strongly interacting matter, as
determined in finite temperature lattice QCD.


title: Pseudoscalar singlet physics with staggered fermions

abstract:
  We report on progress in measuring disconnected correlators associated with
pseudoscalar flavor-singlet mesons. This will eventually allow us to compute
the masses of the eta and eta' mesons. Flavor-singlet physics also presents an
interesting test of the staggered fermion formulation, as disconnected
correlators are sensitive to whether the same action governs both sea quarks
and valence quarks. It can also help test the validity of the ``fourth-root
trick'' used in unquenched lattice calculations where the number of flavors
$N_f<4$.


title: Scaling test of quenched Wilson twisted mass QCD at maximal twist

abstract:
  We present the results of an extended scaling test of quenched Wilson twisted
mass QCD. We fix the twist angle by using two definitions of the critical mass,
the first obtained by requiring the vanishing of the pseudoscalar meson mass
m_PS for standard Wilson fermions and the second by requiring restoration of
parity at non-zero value of the twisted mass mu and subsequently extrapolating
to mu=0. Depending on the choice of the critical mass we simulate at values of
beta in [5.7,6.45], for a range of pseudoscalar meson masses 250 MeV < m_PS < 1
GeV and we perform the continuum limit for the pseudoscalar meson decay
constant f_PS and various hadron masses (vector meson m_V, baryon octet m_oct
and baryon decuplet m_dec) at fixed value of r_0 m_PS. For both definitions of
the critical mass, lattice artifacts are consistent with O(a) improvement.
However, with the second definition, large O(a^2) discretization errors present
at small quark mass with the first definition are strongly suppressed. The
results in the continuum limit are in very good agreement with those from the
Alpha and CP-PACS Collaborations.


title: The Kaon B-Parameter in Staggered Chiral Perturbation Theory

abstract:
  We calculate the kaon B-parameter, B_K, to next-to-leading order in staggered
chiral perturbation theory. We extend the usual power counting to include the
effects of using perturbative (rather than non-perturbative) matching factors.
Taste breaking enters through the O(a^2) terms in the effective action, through
mixing with higher-dimension operators, and through the truncation of matching
factors. These effects cause mixing with several additional operators,
complicating the chiral and continuum extrapolations. We summarize the results
here; all details can be found in hep-lat/0507012.


title: Meson decay constants from Nf=2 clover fermions

abstract:
  We present recent results for meson decay constants calculated on
configurations with two flavours of O(a)-improved Wilson fermions.
Non-perturbative renormalisation is applied and quark mass dependencies as well
as finite volume and discretisation effects are investigated. In this work we
also present a computation of the coupling of the light vector mesons to the
tensor current using dynamical fermions.


title: NRQCD results on the MILC extra coarse ensemble

abstract:
  We present preliminary results using NRQCD to describe heavy quarks on the
MILC 2+1 flavour dynamical extra coarse ensemble. We calculate the spectra of
low lying states in bottomonium to complement earlier results on the finer MILC
ensembles. We then exploit the coarseness of the lattices to calculate charm
propagators using NRQCD. These are used to examine the charmonium spectrum and
to calclate the mass of the $B_c$ using NRQCD. Finally we look breifly at the
$B_d$ and $B_s$ systems using the imporoved staggered formalism to describe the
light valence quarks.


title: B semileptonic decays with 2+1 dynamical quark flavors

abstract:
  We study semileptonic B decays, using MILC dynamical configurations with
$N_f=2+1$. NRQCD heavy and AsqTad light quark actions are used. We obtain the
semileptonic form factors $f_+(q^2)$ and $f_0(q^2)$ in the chiral limit.


title: Radiative Transitions in Charmonium

abstract:
  The form factors for the radiative transitions between charmonium mesons are
investigated. We employ an anisotropic lattice using a Wilson gauge action, and
domain-wall fermion action. We extrapolate the form factors to $Q^2 = 0$,
corresponding to a real photon, using quark-model-inspired functions. Finally,
comparison is made with photocouplings extracted from the measured radiative
widths, where known. Our preliminary results find photocouplings commensurate
with these experimentally extracted values.


title: Algorithm Shootout: R versus RHMC

abstract:
  We present initial results comparing the RHMC and R algorithms on large
lattices with small quark masses using chiral fermions. We also present results
concerning staggered fermions near the deconfinement/chiral phase transition.
We find that the RHMC algorithm not only eliminates the step-size error of the
R algorithm, but is also considerably more efficient. We discuss several
possibilities for further improvement to the RHMC algorithm.


title: $B_7$, $B_8$ and chiral Ward identities

abstract:
  We present recent progress in understanding weak matrix elements on the
lattice. We use HYP staggered fermions in quenched QCD to study numerically
various properties of the $K^+\to\pi^+$ amplitudes of the electroweak penguin
operators $Q_7$ and $Q_8$. We check chiral Ward identities to probe the
validity of using improved staggered fermions in the calculation of weak matrix
elements. We address the issue of mixing with unphysical lower dimension
operators, which causes a divergent term in the case of the $\Delta I = 1/2$
amplitudes. We propose a particular subtraction method as the best choice. We
also measure the gold-plated ratio $R$ originally suggested by Becirevic and
Villadoro.


title:
Staggered Lattice Artifacts in 3-Flavor Heavy Baryon Chiral Perturbation
  Theory

abstract:
  Motivated by simulation results for octet and decuplet baryon masses using
2+1 flavors of light staggered quarks, we are incorporating staggered lattice
artifacts into heavy baryon chiral perturbation theory, calculating the masses
of various staggered baryons, and studying the connection between the staggered
baryons of the chiral theory and the staggered baryons of simulations. We
present order (m_q)^(3/2) loop contributions to the masses of several staggered
nucleons and discuss interpolating fields that create these states.


title: Calculating $B_K$ using a mixed action

abstract:
  We present preliminary results of $B_K$ calculated using improved staggered
fermions with the mixed action (valence quarks = HYP staggered fermions and sea
quarks = AsqTad staggered fermions). We analyze the data based upon the
prediction by Van de Water and Sharpe. A hint of consistency with the
prediction is observed. We also present preliminary results of $B_8^{(3/2)}$
and $B_7^{(3/2)}$.


title: Non-degenerate quark mass effect on $B_K$ with a mixed action

abstract:
  We investigate the effect of non-degenerate quarks on $B_K$. This effect is
noticeably large for $B_K$ (significantly larger than statistical uncertainty).
Hence, it is important to include this effect in order to determine $B_K$ with
higher precision. We also observe that the quality of fitting for $B_K$ gets
better when we include non-degenerate combinations to fit to the prediction by
Van de Water and Sharpe. However, this effect on $B_7^{(3/2)}$ and
$B_8^{(3/2)}$ turns out to be relatively small.


title: Hadron Spectrum from Lattice QCD

abstract:
  A brief review is given of the lattice QCD calculation of the hadron
spectrum. The status of current attempts toward inclusion of dynamical up, down
and strange quarks is summarized focusing on our own work. Recent work on the
possible existence of pentaquark states are assessed. We touch upon the PACS-CS
Project for building our next machine for lattice QCD, and conclude with a
near-term physics and machine prospects.


title: The PACS-CS Project

abstract:
  We describe our plan to develop a large-scale cluster system with a peak
speed of 14.3Tflops for lattice QCD at the Center for Computational Sciences,
University of Tsukuba, as a successor to the current 0.6Tflops CP-PACS
computer. The system consist of 2560 nodes connected by a 16x16x10
three-dimensional hyper crossbar network. Each node has a single low-voltage
2.8GHz Xeon processor and 2GBytes of memory with 6.4GBytes/sec bandwidth, and
160 GBytes of disk in RAID1 mode. The network link in each of the three
directions is made of dual Gigabit Ethernet with the peak throughput of
250MByte/sec. Hence each node has an aggregate network bandwidth of
750MByte/sec. The system will run under Linux and SCore, and an extension of
the PM driver is developed for the network. The system will be developed
jointly with Hitachi Limited. The installation is scheduled in the first
quarter of Japanese Fiscal 2006 (April-June 2006) and the start of operation is
expected in July 2006.


title: Low-mode averaging for baryon correlation functions

abstract:
  The low-mode averaging technique is a powerful tool for reducing large
fluctuations in correlation functions due to low-mode eigenvalues of the Dirac
operator. In this work we propose a generalization to baryons and test our
method on two-point correlation functions of left-handed nucleons, computed
with quenched Neuberger fermions on a lattice with extension L=1.5 fm. We show
that the statistical fluctuations can be reduced and the baryon signal
significantly improved.


title: The chiral transition in two-flavor QCD

abstract:
  QCD with N_f=2 is a specially interesting system to investigate the chiral
transition. The order of the transition has still not been established. We
report the results of an in-depth numerical investigation performed with
staggered fermions on lattices with L_t=4 and L_s=12,16,20,24,32 and quark
masses am_q ranging from 0.01335 to 0.307036. Using finite-size techniques we
compare the scaling behavior of a number of thermodynamical susceptibilities
with the expectations of O(4) and O(2) universality classes. Clear disagreement
is observed. Indications of a first order transition are found.


title: Confinement and the center of the gauge group

abstract:
  The question of the role of the center of the gauge group in the phenomenon
of confinement in Yang-Mills theory is addressed. The investigation is
performed from the most general perspective of considering all possible choices
for the gauge symmetry group. In this context, an interesting role is played by
G(2) Yang-Mills theory: the simplest pure gauge theory with a trivial center
and without 't Hooft flux vortices. Numerical simulations show the presence of
a first order finite temperature deconfinement phase transition in G(2)
Yang-Mills theory in (3+1) dimensions. Interestingly, the G(2) gauge symmetry
can be broken to an SU(3) subgroup by the Higgs mechanism. We investigate the
relation between the deconfinement phase transition in G(2) and SU(3)
Yang-Mills theories by numerical simulations in the G(2) gauge-Higgs system.


title:
Non-perturbatively renormalised light quark masses from a lattice
  simulation with N_f=2

abstract:
  We present results for the light quark masses obtained from a lattice QCD
simulation with N_f=2 degenerate Wilson dynamical quark flavours. The sea quark
masses of our lattice, of spacing a ~ 0.06 fm, are relatively heavy, i.e., they
cover the range corresponding to 0.60 <~ M_P/M_V <~ 0.75. After implementing
the non-perturbative RI-MOM method to renormalise quark masses, we obtain
m_{ud}^{MS}(2 GeV)=4.3 +- 0.4^{+1.1}_{-0} MeV, and m_s^{MS}(2 GeV)=101 +-
8^{+25}_{-0} MeV, which are about 15% larger than they would be if renormalised
perturbatively. In addition, we show that the above results are compatible with
those obtained in a quenched simulation with a similar lattice.


title: Disconnected Loops with Twisted Mass Lattice QCD

abstract:
  We give a general introduction and discussion of the issues involved in using
the twisted mass formulation of lattice fermions in the context of disconnected
loop calculations, including a short orientation on the present experimental
situation for nucleon strange quark form factors. A prototype calculation of
the disconnected part of the nucleon scalar form factor is described.


title: Tuning anisotropies for dynamical gauge configurations

abstract:
  We present methods and results for the tuning of quark and gluon anisotropies
for improved actions in N_f = 2 QCD.


title: Pionic couplings (g^ and g~) in the static heavy quark limit

abstract:
  The couplings between the soft pion and the doublet of heavy-light mesons are
basic parameters of the ChPT approach to the heavy-light systems. We compute
the unquenched (Nf=2) values of two such couplings in the static heavy quark
limit: (1) g^, coupling to the lowest doublet of heavy-light mesons, and (2)
g~, coupling to the first orbital excitations. A brief description of the
calculation together with a short discussion of the results is presented.


title: K_l3 form factor with two-flavors of dynamical domain-wall quarks

abstract:
  We report on our calculation of K \to \pi vector form factor by numerical
simulations of two-flavor QCD on a 16^3x32x12 lattice at a \simeq 0.12 fm using
domain-wall quarks and DBW2 glue. Our preliminary result at a single sea quark
mass correponding to m_PS/m_V \simeq 0.53 shows a good agreement with previous
estimate in quenched QCD and that from a phenomenological model.


title: $K\to\pi\pi$ from electroweak penguins in $N_f=2$ domain-wall QCD

abstract:
  We present the calculation of $K\to\pi\pi$ matrix elements of electroweak
penguin operators {\it i.e.} $Q_7$ and $Q_8$. In the numerical simulation, we
use the gauge configurations generated by the combination of $N_f=2$
domain-wall fermions and DBW2 gauge action. From $K\to\pi$ and $K\to 0$ matrix
elements on the lattice, we construct $K\to\pi\pi$ matrix elements at
next-to-leading order in the chiral expansion by using recent analytic results.
Renormalization factor of these matrix elements are obtained by the
non-perturbative renormalization technique in RI/MOM scheme. Brief discussion
based on our results are made as well as a comparison with previous works.


title:
Geometry of three dimensional vacuum domains in four dimensional SU(2)
  gluodynamics

abstract:
  We review briefly recent results of lattice simulations on 3d domains in the
vacuum state of SU(2) gluodynamics. The defects are defined as unification of
all the negative links in central projection under condition that the total
number of negative links is minimized. In the continuum limit, negative links
correspond, generally speaking to singular fields. The data indicate that total
volume of the defects scales in physical units. We consider also correlator of
negative links. The correlator scales in physical units as well, within the
error bars. A new observation reported here is a strong anisotropy of the
correlator.


title: Heavy Quark Diffusion and Lattice Correlators

abstract:
  We study charmonia correlators at finite temperature. We analyze to what
extent heavy quarkonia correlators are sensitive to the effect of heavy quark
transport and whether it is possible to constrain the heavy quark diffusion
constant by lattice calculations. Preliminary lattice calculations of quarkonia
correlators performed on anisotropic lattices show that they are sensitive to
the effect of heavy quark transport, but much detailed calculations are
required to constrain the value of the heavy quark diffusion constant.


title: Finite-volume effects in moving frames

abstract:
  We determine the quantization condition for the energy levels of two
interacting particles in a finite box in a ``moving frame'', i.e. one in which
the total momentum of pions is non-zero. This condition is valid up to
corrections which fall exponentially withe the box size, and holds only below
the inelastic threshold. It is derived using field theoretic methods, using a
generalization of previous summation formulae relating sums and integrals over
momenta. The result agrees with that obtained earlier by Rummakainen and
Gottlieb using a relativistic quantum mechanical approach. Technically, we
expand the finite-volume four-point Green function in terms of the
infinite-volume Bethe-Salpeter kernel, and determine the position of the poles.
The final result is written in terms of the two-pion scattering phase shift.
Our result can be used to facilitate the determination of the scattering phase
shift, and can be used to generalize the Lellouch-L\"uscher formula relating
finite-volume two-particle matrix elements to those in infinite volume.


title: 3-point functions from twisted mass lattice QCD at small quark masses

abstract:
  We show at the example of the matrix element between pion states of a
twist-2, non-singlet operator that Wilson twisted mass fermions allow to
compute this phenomenologically relevant quantitiy at small pseudo scalar
masses of O(270 MeV). In the quenched approximation, we investigate the scaling
behaviour of this observable that is derived from a 3-point function by
applying two definitions of the critical mass and find a scaling compatible
with the expected O(a^2) behaviour in both cases. A combined continuum
extrapolations allows to obtain reliable results at small pion masses, which
previously could not be explored by lattice QCD simulations.


title: Ginsparg-Wilson Pions Scattering in a Sea of Staggered Quarks

abstract:
  We calculate isospin 2 pion-pion scattering in chiral perturbation theory for
a partially quenched, mixed action theory with Ginsparg-Wilson valence quarks
and staggered sea quarks. We point out that for some scattering channels, the
power-law volume dependence of two pion states in nonunitary theories such as
partially quenched or mixed action QCD is identical to that of QCD. Thus one
can extract infinite volume scattering parameters from mixed action
simulations. We then determine the scattering length for both 2 and 2+1 sea
quarks in the isospin limit. The scattering length, when expressed in terms of
the pion mass and the decay constant measured on the lattice, has no
contributions from mixed valence-sea mesons, thus it does not depend upon the
parameter, C_Mix, that appears in the chiral Lagrangian of the mixed theory. In
addition, the contributions which nominally arise from operators appearing in
the mixed action O(a^2 m_q) Lagrangian exactly cancel when the scattering
length is written in this form. This is in contrast to the scattering length
expressed in terms of the bare parameters of the chiral Lagrangian, which
explicitly exhibits all the sicknesses and lattice spacing dependence allowed
by a partially quenched mixed action theory. These results hold for both 2 and
2+1 flavors of sea quarks.


title: More evidence of localization in the low-lying Dirac spectrum

abstract:
  We have extended our computation of the inverse participation ratio of
low-lying (asqtad) Dirac eigenvectors in quenched SU(3). The scaling dimension
of the confining manifold is clearer and very near 3. We have also computed the
2-point correlator which further characterizes the localization.


title:
Remarks on the Maximum Entropy Method applied to finite temperature
  lattice QCD

abstract:
  We make remarks on the Maximum Entropy Method (MEM) for studies of the
spectral function of hadronic correlators in finite temperature lattice QCD. We
discuss the virtues and subtlety of MEM in the cases that one does not have
enough number of data points such as at finite temperature. Taking these points
into account, we suggest several tests which one should examine to keep the
reliability for the results, and also apply them using mock and lattice QCD
data.


title:
Cho-Faddeev-Niemi decomposition of lattice Yang-Mills theory and
  evidence of a novel magnetic condensation

abstract:
  We present the first implementation of the Cho--Faddeev--Niemi ecomposition
of the SU(2) Yang-Mills field on a lattice. Our construction retains the color
symmetry (global SU(2) gauge invariance) even after a new type of Maximally
Abelian gauge, as explicitly demonstrated by numerical simulations.


title: Towards an algebraic approach to the discretisation of fermions

abstract:
  A discretisation scheme for differential geometry is applied to the problem
of constructing lattice actions, the naive and staggered action are thus
derived. It is found that after specifying an ansatz for the space of fields,
the corresponding lattice action is obtained. The gauging procedure, and the
applicability of the method to twisted super-symmetry on a lattice is outlined.
Some comments on the QED axial anomaly are made, for the theory in which the
lattice projection operator is not inserted.


title: Optimization of Lattice QCD codes for the AMD Opteron processor

abstract:
  We report our experience of the optimization of the lattice QCD codes for the
new Opteron cluster at DESY Hamburg, including benchmarks. Details of the
optimization using SSE/SSE2 instructions and the effective use of prefetch
instructions are discussed.


title: Supersymmetric Yang-Mills quantum mechanics in various dimensions

abstract:
  Supersymmetric Yang-Mills quantum mechanics (SYMQM) results from the
dimensional reduction of the Yang-Mills field theory in $D$ space-time
dimensions to a single point in the $D-1$ dimensional space. It can be also
viewed as the effective quantum mechanics of zero momentum modes of the
original theory. These systems were first considered in 80's as simple models
with supersymmetry. Independently, zero-volume field theories (especially pure
Yang-Mills) were employed as the starting point of the small volume expansion,
which is an important theoretical tool complementary to early lattice
calculations. Later the models attracted a new wave of interest after the
hypothesis of the equivalence, between the $D=10, SU(\infty)$ SYMQM and a
M-theory of D0 branes. In this talk some new results obtained for the D=4
system with SU(2) gauge symmetry will be presented.


title: Meson correlation functions at high temperatures

abstract:
  We present preliminary results for the correlation- and spectral functions of
different meson channels on the lattice. The main focus lies on gaining control
over cut-off as well as on the finite-volume effects. Extrapolations of
screening masses above the deconfining temperature are guided by the result of
the free ($T=\infty$) case on the lattice and in the continuum. We study the
quenched non-perturbatively improved Wilson-clover fermion as well as the
hypercube fermion action which might show less cut-off effects.


title: Bound state spectrum in the finite volume

abstract:
  The signature of bound state formation on the lattice is of particular
interest in this talk. In the finite volume, where all states have discrete
energies, it is rather hard to distinguish between a bound state and a
scattering state if the bound state were close to threshold, i.e., like a
"loosely bound state". To study bound states in the finite volume, we calculate
the positronium spectroscopy in the Higgs phase of U(1) gauge dynamics, where
the photon is massive and then massive photons give rise to the short-ranged
interparticle force. We try to identify bound state formation on the basis of
the Luscher's finite size method, which suggests specific volume dependences of
the energy gap/shift from the threshold energy for either bound states or
scattering states.


title:
On the determination of low-energy constants for $\Delta S=1$
  transitions

abstract:
  We present our preliminary results for three-point correlation functions
involving the operators entering the $\Delta{S}=1$ effective Hamiltonian with
an active charm quark, obtained using overlap fermions in the quenched
approximation. This is the first computation carried out for valence quark
masses small enough so as to permit a matching to Quenched Chiral Perturbation
Theory in the $\epsilon$-regime. The commonly observed large statistical
fluctuations are tamed by means of low-mode averaging techniques, combined with
restrictions to individual topological sectors. We also discuss the matching of
the resulting hadronic matrix elements to the effective low-energy constants
for $\Delta{S}=1$ transitions. This involves (a) finite-volume corrections
which can be evaluated at NLO in Quenched Chiral Perturbation Theory, and (b)
the short-distance renormalization of the relevant four-quark operators in
discretizations based on the overlap operator. We discuss perturbative
estimates for the renormalization factors and possible strategies for their
non-perturbative evaluation. Our results can be used to isolate the
long-distance contributions to the $\Delta I=1/2$ rule, coming from physics
effects around the intrinsic QCD scale.


title: The glue-ball spectrum of pure percolation

abstract:
  We present a high-precision numerical study of 3D random percolation viewed
as a confining gauge theory. Using large correlation matrices among multiform
Wilson loops we determine the low-lying masses in various spin channels.


title: Thermodynamics using p4-improved staggered fermion action on QCDOC

abstract:
  We present an exploratory study of the thermodynamics of $N_f=3$ QCD with an
improved staggered fermions using the QCDOC supercomputer. We use a p4 action
with MILC-style smeared links (Fat 7). Some details of the implementation of
the p4 action on QCDOC are discussed and performance benchmarks are given. We
show preliminary results for the quark mass dependence of the pseudo-critical
temperature $T_c$ from several lattice volumes . We also make a comparison
between p4fat7 and the old p4 action.


title: A Review of Pentaquark Calculations on the Lattice

abstract:
  We review lattice calculations of pentaquarks and discuss issues pertaining
to interpolation fields, distinguishing the signal of pentaquarks from those of
the KN scattering states, chiral symmetry, and ghost state contaminations.


title: Perturbative Study of the Supersymmetric Lattice Model from Matrix Model

abstract:
  We study the lattice model for the supersymmetric Yang-Mills theory in two
dimensions proposed by Cohen, Kaplan, Katz, and Unsal. We re-examine the formal
proof for the absence of susy breaking counter terms as well as the stability
of the vacuum by an explicit perturbative calculation for the case of U(2)
gauge group. Introducing fermion masses and treating the bosonic zero momentum
mode nonperturbatively, we avoid the infra-red divergences in the perturbative
calculation. As a result, we find that there appear mass counter terms for
finite volume which vanish in the infinite volume limit so that the theory
needs no fine-tuning.


title:
Understanding the U(1) problem through dyon configuration in the Abelian
  projection

abstract:
  We give a short review of the recently obtained result that the magnetic
monopole promoted to the dyon due to the vacuum angle $\theta$ resolves the
U(1) problem in the sense that the dyon obtained in this way gives a dominant
contribution to the topological susceptibility


title: Viscosities of Hot Gluon -- A Lattice QCD Study --

abstract:
  We present transport coefficients (shear viscosity, $\eta$, and bulk
viscosity, $\zeta$) for the gluon system obtained by the lattice QCD. This is
an indispensable calculation towards the understanding of ``New State of
Matter'' observed in RHIC. We study the temperature regions of RHIC ($1.4 \leq
T/T_c \leq 1.8$) and much higher ones up to $ T/T_c \sim 20$. In RHIC regions,
the ratio of shear viscosity to entropy density, $\eta/s$, is around $\sim
0.1-0.4$, and satisfies the KSS bound. At high temperature, $\eta$ becomes two
or three oder of magnitude larger. Our calculation has two limitations: (i) the
use of the quench approximation, i.e., without quark pair creation-annihilation
effects on vacuum, and (ii) the use of an ansatz for the spectral function. The
first point has been well studied in calculations of the spectroscopy and the
phase-transition behavior. To investigate the second point, we compare our
results with perturbative calculations in high $T$-regions, and also check the
effects of the modification of the spectral function on the viscosity.


title: A new efficient Cluster Algorithm for the Ising Model

abstract:
  Using D-theory we construct a new efficient cluster algorithm for the Ising
model. The construction is very different from the standard Swendsen-Wang
algorithm and related to worm algorithms. With the new algorithm we have
measured the correlation function with high precision over a surprisingly large
number of orders of magnitude.


title: An Efficient Cluster Algorithm for CP(N-1) Models

abstract:
  We construct an efficient cluster algorithm for ferromagnetic SU(N)-symmetric
quantum spin systems. Such systems provide a new regularization for CP(N-1)
models in the framework of D-theory, which is an alternative non-perturbative
approach to quantum field theory formulated in terms of discrete quantum
variables instead of classical fields. Despite several attempts, no efficient
cluster algorithm has been constructed for CP(N-1) models in the standard
formulation of lattice field theory. In fact, there is even a no-go theorem
that prevents the construction of an efficient Wolff-type embedding algorithm.
We present various simulations for different correlation lengths, couplings and
lattice sizes. We have simulated correlation lengths up to 250 lattice spacings
on lattices as large as 640x640 and we detect no evidence for critical slowing
down.


title: The Status of D-Theory

abstract:
  Field theories are usually quantized by performing a path integral over
configurations of classical fields. This is the case both in perturbation
theory and in Wilson's nonperturbative lattice field theory. D-theory is an
alternative nonperturbative formulation of field theory in which classical
fields emerge from the low-energy collective dynamics of discrete quantum
variables (quantum spins and their gauge analogs -- quantum links) which
undergo dimensional reduction. D-theory was developed some time ago as a
discrete approach to U(1) and SU(2) pure gauge theories, extended to SU(N)
gauge theories and full QCD, and also applied to a variety of other models. On
the practical side, D-theory provides a framework for the development of
efficient numerical methods, such as cluster algorithms. For example, in the
D-theory formulation of CP(N-1) models one can simulate efficiently at non-zero
chemical potential or at non-zero vacuum angle theta. On the conceptual side,
D-theory offers a natural solution for the nonperturbative hierarchy problem of
chiral symmetry in QCD. We also take a broader nonperturbative view on
fundamental physics and speculate that D-theory variables -- i.e. quantum spins
and quantum links -- may be promising candidates for the physical degrees of
freedom that Nature has chosen to regularize the standard model physics at
ultra-short distances.


title: Unitary Evolution on a Discrete Phase Space

abstract:
  We construct unitary evolution operators on a phase space with power of two
discretization. These operators realize the metaplectic representation of the
modular group SL(2,Z_{2^n}). It acts in a natural way on the coordinates of the
non-commutative 2-torus, T_{2^n}^2$ and thus is relevant for non-commutative
field theories as well as theories of quantum space-time. The class of
operators may also be useful for the efficient realization of new quantum
algorithms.


title:
Fluctuations, strangeness and quasi-quarks in heavy-ion collisions from
  lattice QCD

abstract:
  We report measurements of diagonal susceptibilities for the baryon number,
chi_B, electrical charge, chi_Q, third component of isospin, chi_I,
strangeness, chi_S, and hypercharge, chi_Y, as well as the off-diagonal chi_BQ,
chi_BY, chi_BS, etc. We show that the ratios of susceptibilities in the high
temperature phase are robust variables, independent of lattice spacing, and
therefore give predictions for experiments. We also investigate strangeness
production and flavour symmetry breaking matrix elements at finite temperature.
Finally, we present evidence that in the high temperature phase of QCD the
different flavour quantum numbers are excited in linkages which are exactly the
same as one expects from quarks. We present some investigations of these
quark-like quasi particles.


title: Non-perturbative renormalisation for overlap fermions

abstract:
  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 <x>. 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.


title: Stochastic Perturbation Theory and the Gluon Condensate

abstract:
  On the lattice searching for the gluon condensate is difficult because a
large perturbative contribution to the expectation value of the action has to
be subtracted before looking for a small contribution from a possible gluon
condensate. The perturbative calculation therefore has to be very precise. We
use a modified version of stochastic perturbation theory to calculate a
perturbative series in a boosted coupling, which converges more rapidly than
the series with the usual lattice coupling, reducing the uncertainties in our
results. We do not see any condensate of dimension two, as suggested by some
earlier lattice studies, but we do find a contribution from a dimension four
condensate. The value of this condensate is approximately 0.04(1) GeV^4, but
with large uncertainties.


title: Scaling test of fermion actions in the Schwinger model

abstract:
  We discuss the scaling behaviour of different fermion actions in dynamical
simulations of the 2-dimensional massive Schwinger model. We have chosen
Wilson, hypercube, twisted mass and overlap fermion actions. As physical
observables, the pion mass and the scalar condensate are computed for the above
mentioned actions at a number of coupling values and fermion masses. We also
discuss possibilities to simulate overlap fermions dynamically avoiding
problems with low-lying eigenvalues of the overlap kernel.


title: Study of 1/m corrections in HQET

abstract:
  We report our exploratory study on the matching condition of HQET with QCD
including 1/m corrections. We introduce a new observable from the dependence of
the heavy-light effective energy on the twisted boundary condition parameter
$\theta$, which could be used to match the kinetic term $\vec{D}^2/(2m)$.
Carrying out quenched QCD simulations for fixed lattice spacing in small
volumes with O(a)-improved Wilson fermions, we study the 1/m dependence of this
observable, from which the static limit and 1/m coefficient can be extracted.
We also compare our preliminary result with HQET.


title: Meson correlators in a finite volume near the chiral limit

abstract:
  We report on the results of our calculation of meson correlators in a finite
volume. The calculation is carried out in the quenched approximation near the
chiral limit (down to Mq = 2.6 MeV) using the overlap fermion. For these small
quark masses, the scalar and pseudo-scalar correlators are well approximated
with a few hundred eigenmodes. The results for both connected and disconnected
correlators are compared with the theoretical predictions of quenched chiral
perturbation theory.


title: Nucleon Structure from Quenched Overlap Fermions

abstract:
  We compute the lowest moments of the nucleon's structure functions using
quenched overlap fermions at two different lattice spacings. The
renormalisation is done nonperturbatively in the RI'-MOM-scheme.


title: Anatomy of String Breaking in QCD

abstract:
  We investigate the string breaking mechanism in n_f=2 QCD. We discuss the
lattice techniques used and present results on energy levels and mixing angle
of the static BBbar|QbarQ two-state system. The string breaking is visualized,
by means of an animation of the action density distribution as a function of
the static colour source-antisource separation.


title:
Distributing the chiral and flavour components of Dirac-Kahler fermions
  across multiple lattices

abstract:
  We use a specific implementation of discrete differential geometry to
describe Dirac-Kahler fermions in such a way that we can separate their chiral
and flavour components. The formulation introduces additional lattices so that
on each lattice there is a single field of definate chirality. Within this
framework, we define an non-compact Abelian gauge theory.


title: High Precision Fundamental Constants using Lattice Perturbation Theory

abstract:
  The HPQCD collaboration has a program for determining the fundamental
constants of the Standard Model Lagrangian from lattice QCD. The most accurate
method of doing this uses the n_f=2+1 improved staggered MILC ensembles with
chiral fitting and multi-loop perturbative renormalisation to connect to the
continuum \msbar scheme. This program has already been very successful with the
recent strong coupling constant determination at three-loops from 28
observables at three lattice spacings, and the one-loop light quark mass
calculation last year. Here a preliminary result is presented for the
first-ever lattice determination of the two-loop multiplicative quark mass
renormalisation. The perturbative calculation involved was automated in the
generation of the Feynman rules, and the generation and coding of all of the
roughly 30 Feynman diagrams. The full formal framework for lattice quark mass
renormalisation is given, including the cancellation of infrared divergences in
intermediate diagrams. The result was checked by evaluation in three separate
gauges and by two authors independently, showing the incredible flexibility and
power of this perturbative methodology. Our preliminary result for the two-loop
perturbative matching factor, and of systematic errors associated with
higher-orders, gives \msbar masses at a 2 GeV scale of $m_s = 87(0)(4)(4)(0)$
MeV, and $\frac12(m_u+m_d) = 3.3(0)(2)(2)(0)$ MeV, where the respective
uncertainties are from lattice statistical, lattice systematic, perturbative,
and electromagnetic and isospin effects. The perturbative errors are a factor
of two smaller than in our previous study, and we anticipate reducing this
somewhat further from additional analysis of the systematics.


title: Notes on (twisted) lattice supersymmetry

abstract:
  We describe a new approach to the problem of putting supersymmetric theories
on the lattice. The basic idea is to discretize a {\it twisted} formulation of
the supersymmetric theory. For certain theories with extended supersymmetry
these twisted formulations contain only integer spin fields. The twisting
exposes a scalar nilpotent supercharge which generates an exact lattice
symmetry. We gives examples from quantum mechanics, sigma models and Yang-Mills
theories.


title: Deconfinement phase transitions in external fields

abstract:
  We compare vacuum dynamics of abelian versus non abelian lattice gauge
theories in presence of external fields. We find that the deconfinement
temperature of non abelian theories depends on the strength of a constant
abelian chromomagnetic field end eventually goes to zero. On the contrary such
an effect is not shared by abelian theories. We argue on the relevance of this
result to understand the QCD vacuum.


title:
Probing the chiral phase transition of N_f=2 clover fermions with
  valence overlap fermions

abstract:
  Overlap fermions are a powerful tool for investigating the chiral and
topological structure of the vacuum and the thermal states of QCD. We study
various chiral and topological aspects of the finite temperature phase
transition of N_f=2 flavours of O(a) improved Wilson fermions, using valence
overlap fermions as a probe. Particular emphasis is placed upon the analysis of
the spectral density and the localisation properties of the eigenmodes as well
as on the local structure of topological charge fluctuations in the vicinity of
the chiral phase transition. The calculations are done on 16^3x8 lattices
generated by the DIK collaboration.


title: OPE Analysis of QCD Potential and Determination of Lambda_MSbar

abstract:
  We analyze the static QCD potential in the distance region 0.1 fm < r < 1 fm.
We combine most recent lattice computations and perturbative computations of
the potential, in the framework of operator-product expansion (OPE). We
determine simultaneously the non-perturbative contribution to the potential,
delta E_US(r), and the relation between the lattice scale (Sommer scale) and
Lambda_MSbar in the quenched approximation. We find that (1) large part of the
short-distance linear potential belongs to the perturbative Wilson coefficient,
(2) delta E_US(r) =0 is disfavored, and (3) r_0 Lambda_MSbar^(3-loop)=0.574 +-
0.042 . It provides a new method for precise determination of r_0 Lambda_MSbar.


title: $B \to D^* l \nu$ with staggered chiral perturbation theory

abstract:
  An unquenched calculation of the form factor for $B\to D^* l \nu$ is needed
to improve the determination of $|V_{cb}|$. The MILC lattices, computed with a
2+1 improved staggered action for the light quarks, are well suited to this
purpose. The relevant staggered chiral perturbation theory (SChPT) must be
known in order to correctly account for the "taste" breaking discretization
effects associated with the staggered quarks to NLO in $1/ m_{D^*}$. This SChPT
calculation is presented.


title:
Determination of the spin-dependent potentials with the multi-level
  algorithm

abstract:
  The spin-dependent corrections to the static interquark potential are
relevant to describing the fine and hyper-fine splittings of the heavy
quarkonium spectra. We investigate these corrections in SU(3) lattice gauge
theory with the Polyakov loop correlation function as the quark source by
applying the multi-level algorithm. We observe remarkably clean signals for the
spin-dependent potentials up to intermediate distances.


title: Charmonium Spectrum on dynamical anisotropic lattices

abstract:
  We present a first study of the charmonium spectrum on N_f=2 dynamical,
anisotropic lattices. We take advantage of all-to-all quark propagators to
build spatially extended interpolating operators to increase the overlap with
states not easily accessible with point propagators such as radially excited
states of eta_c, psi, and chi_c, D-waves and hybrid states.


title:
The axial charge of the nucleon on the lattice and in chiral
  perturbation theory

abstract:
  We present recent Monte Carlo data for the axial charge of the nucleon
obtained by the QCDSF-UKQCD collaboration for N_f=2 dynamical quarks. We
compare them with formulae from chiral perturbation theory in finite and
infinite volume and find a remarkably consistent picture.


title: The nucleon axial charge in full lattice QCD

abstract:
  The nucleon axial charge is calculated as a function of the pion mass in full
QCD. Using domain wall valence quarks and improved staggered sea quarks, we
present the first calculation with pion masses as light as 354 MeV and volumes
as large as (3.5 fm)^3. We show that finite volume effects are small for our
volumes and that a constrained fit based on finite volume chiral perturbation
theory agrees with experiment within 7% statistical errors.


title: Critical behavior of strongly coupled lattice QCD at finite temperature

abstract:
  We study the critical behavior of lattice Quantum Chromodynamics (QCD) in the
strong coupling approximation with Kogut-Susskind and Wilson fermions at finite
temperature ($T$) and zero chemical potential. Using the Hamiltonian
formulation we construct a mean field solution to the equation of motion at
finite $T$ and use it to study the elementary thermal excitations and to
extract some critical exponents characterizing the observed second order phase
transition. We find similar critical behaviors for Kogut-Susskind and Wilson
fermions at finite $T$


title:
HMC algorithm with multiple time scale integration and mass
  preconditioning

abstract:
  We describe a new HMC algorithm variant we have recently introduced and
extend the published results by preliminary results of a simulation with a
pseudo scalar mass value of about 300 MeV. This new run confirms our
expectation that simulations with such pseudo scalar mass values become
feasible and affordable with our HMC variant. In addition we discuss
simulations from hot and cold starts at a pseudo scalar mass value of about 300
MeV, which we performed in order to test for possible meta-stabilities.


title: Confinement in QCD: Results and Open Problems

abstract: Progress is reviewed in the understanding of color confinement .


title:
Scalar glueball and meson spectroscopy in unquenched lattice QCD with
  improved staggered quarks

abstract:
  We present results of an exploratory study of singlet scalar states in
unquenched QCD using both glueball and meson operators. Results for non-singlet
non-strange scalar mesons are also presented. We use Asqtad improved staggered
fermions and gauge configurations generated by the MILC collaboration at
lattice spacings of .12 and .09 fm. In this formulation, the glueball mass is
not significantly different from the quenched value at finite lattice spacing.
Significant taste violations are present in the scalar sector. At light quark
masses, decay channels complicate the mass determinations. There is some
evidence that the non-strange singlet meson lies below the non-singlet meson.


title:
An upper limit to the electric dipole moment of the neutron from lattice
  QCD

abstract:
  A linear increase with the volume of the topological susceptibility can
signal spontaneous breaking of parity and time inversion, due to a nonzero
vacuum expectation value of the topological charge. Such a breaking would
produce a nonzero electric dipole moment of the neutron, d_n. An upper limit to
d_n is derived from numerical simulations at increasing volumes.


title: Kaon semileptonic decay form factors in two-flavor QCD

abstract:
  We present a calculation of the kaon form factors in two-flavor QCD with the
non-perturbatively $O(a)$-improved Wilson quark action. In order to achieve a
few percent accuracy in the study of SU(3) breaking effects, we use a set of
double ratios of the matrix elements, with which the bulk of the statistical
fluctuation and the multiplicative renormalization factors cancel.


title: The 3-state Potts model as a heavy quark finite density laboratory

abstract:
  The 3-D Z(3) Potts model is a model for finite temperature QCD with heavy
quarks. The chemical potential in QCD becomes an external magnetic field in the
Potts model. Following Alford et al.\cite{Alford_et_al}, we revisit this
mapping, and determine the phase diagram for an arbitrary chemical potential,
real or imaginary. Analytic continuation of the phase transition line between
real and imaginary chemical potential can be tested with precision. Our results
show that the chemical potential weakens the heavy-quark deconfinement
transition in QCD.


title: Power Counting Regime of Chiral Extrapolation and Beyond

abstract:
  Finite-range regularised (FRR) chiral effective field theory is presented in
the context of approximation schemes ubiquitous in modern lattice QCD
calculations. Using FRR techniques, the power-counting regime (PCR) of chiral
perturbation theory can be estimated. To fourth-order in the expansion at the
1% tolerance level, we find m_\pi < 180 MeV for the PCR, extending only a small
distance beyond the physical pion mass.


title: Heavy-light mesons with domain wall fermions

abstract:
  We present RBC heavy-light meson spectroscopy with quenched DBW2 gauge
configurations at lattice cutoff of about 3 GeV. Both heavy and light quarks
are described by domain-wall fermions (DWF). The heavy quark mass ranges
between 0.1 and 0.4 lattice units, covering charm. The light quark mass ranges
between 0.008 and 0.04, covering strange. In particular, we discuss charmed (D
and D*) and charm-strange (Ds and DsJ) mesons with spin-parity JP= 0+/- and
1+/-. The preliminary results indicate that DWF describe charm on the quenched
DBW2 ensemble at this cutoff. The masses of the JP=0+/- and 1+/- D, D*, Ds and
DsJ meson states are well reproduced to within a few %; their parity splitting,
DeltaJ, are better reproduced than previous works, with only 10-20 % over
estimations; the experimental observation that the splitting for non-strange
states is bigger than that for strange states is reproduced as well; but the
hyperfine splittings are only 60-65 % reproduced. Regarding the depenence on
heavy quark mass, J=0 and J=1 parity splittings are degenerate for heavy quark
mass heavier than 0.2-0.3 lattice units a; the J=0 parity splitting increases
as the heavy quark mass decreases further while the J=1 splitting does not.


title: Onium Masses with Three Flavors of Dynamical Quarks

abstract:
  We have greatly extended an earlier calculation of the charmonium spectrum on
three flavor dynamical quark ensembles by using more recent ensembles generated
by the MILC collaboration. The heavy quarks are treated using the Fermilab
formulation. The charmonium state masses are in reasonable agreement with the
observed spectrum; however, some of the spin splittings may still be too small.


title: Towards a chiral gauge theory by deconstruction in AdS5

abstract:
  We describe an implementation of a deconstructed gauge theory with charged
fermions defined on an interval in five dimensional AdS space. The four
dimensional slices are Minkowski, and the end slices support four dimensional
chiral zero modes. In such a theory, the energy scales warp down as we move
along the fifth dimension. If we augment this theory with localized neutral
4-dimensional Majorana fermions on the low energy end, and implement a Higgs
mechanism there, we can arrange the theory such that the lightest gauge boson
mode and the chiral mode on the wall at the high energy end are parametrically
lighter than all the other states in the theory. If this semiclassical
construction does not run into problems at the quantum level, this may provide
an explicit construction of a chiral gauge theory. Instanton effects are
expected to make the gauge boson heavy only if the resulting effective theory
is anomalous.


title: Glueball Spectrum and Matrix Elements on Anisotropic Lattices

abstract:
  The glueball-to-vacuum matrix elements of local gluonic operators in scalar,
tensor, and pseudoscalar channels are investigated numerically on several
anisotropic lattices with the spatial lattice spacing ranging from 0.1fm -
0.2fm. These matrix elements are needed to predict the glueball branching
ratios in $J/\psi$ radiative decays which will help identify the glueball
states in experiments. Two types of improved local gluonic operators are
constructed for a self-consistent check and the finite volume effects are
studied. We find that lattice spacing dependence of our results is very weak
and the continuum limits are reliably extrapolated, as a result of improvement
of the lattice gauge action and local operators. We also give updated glueball
masses with various quantum numbers.


title: Locality and Scaling of Quenched Overlap Fermions

abstract:
  The overlap fermion offers the tremendous advantage of exact chiral symmetry
on the lattice, but is numerically intensive. This can be made affordable while
still providing large lattice volumes, by using coarse lattice spacing, given
that good scaling and localization properties are established. Here, using
overlap fermions on quenched Iwasaki gauge configurations, we demonstrate
directly that the overlap Dirac operator's range is comfortably small in
lattice units for each of the lattice spacings 0.20 fm, 0.17 fm, and 0.13 fm
(and scales to zero in physical units in the continuum limit). In particular,
our direct results contradict recent speculation that an inverse lattice
spacing of $1 {\rm GeV}$ is too low to have satisfactory localization.
Furthermore, hadronic masses (available on the two coarser lattices) scale very
well.


title:
Two--dimensional lattice Gross--Neveu model with Wilson twisted mass
  fermions

abstract:
  We study the two-dimensional lattice Gross--Neveu model with Wilson twisted
mass fermions in order to explore the phase structure in this setup. In
particular, we investigate the behaviour of the phase transitions found earlier
with standard Wilson fermions as a function of the twisted mass parameter
$\mu$. We find that qualitatively the dependence of the phase transitions on
$\mu$ is very similar to the case of lattice QCD.


title: The QCD phase diagram at zero and small baryon density

abstract:
  I review recent developments in determining the QCD phase diagram by means of
lattice simulations. Since the invention of methods to side-step the sign
problem a few years ago, a number of additional variants have been proposed,
and progress has been made towards understanding some of the systematics
involved. All available techniques agree on the transition temperature as a
function of density in the regime \mu_q/T < 1. There are by now four
calculations with signals for a critical point, two of them at similar
parameter values and with consistent results. However, it also emerges that the
location of the critical point is exceedingly quark mass sensitive. At the same
time sizeable finite volume, cut-off and step size effects have been uncovered,
demanding additional investigations with exact algorithms on larger and finer
lattices before quantitative conclusions can be drawn. Depending on the sign of
these corrections, there is ample room for the eventual phase diagram to look
as expected or also quite different, with no critical point at all.


title: Unified chiral analysis of the vector meson spectrum from lattice QCD

abstract:
  The chiral extrapolation of the vector meson mass calculated in
partially-quenched lattice simulations is investigated. The leading one-loop
corrections to the vector meson mass are derived for partially-quenched QCD. A
large sample of lattice results from the CP-PACS Collaboration is analysed,
with explicit corrections for finite lattice spacing artifacts. To incorporate
the effect of the opening decay channel as the chiral limit is approached, the
extrapolation is studied using a necessary phenomenological extension of chiral
effective field theory. This chiral analysis also provides a quantitative
estimate of the leading finite volume corrections. It is found that the
discretisation, finite-volume and partial quenching effects can all be very
well described in this framework, producing an extrapolated value of M_\rho in
excellent agreement with experiment. This procedure is also compared with
extrapolations based on polynomial forms, where the results are much less
enlightening.


title: The static quark potential in 2+1 flavour Domain Wall QCD from QCDOC

abstract:
  We report our present status of on-going project on the measurement of the
static quark potential in 2+1 flavour domain wall QCD with various improved
gauge actions and couplings. Lattice spacing determined from Sommer scale on
these ensembles are from 1.6 GeV to 2.0 GeV for $16^3 \times 32$ lattice with
fifth dimension size 8. We also examine size of discretization error from
scaling of a pair of dimensionless quantities, $(r_0 m_\pi)^2$ and $r_0
m_\rho$, and found small scaling violation.


title: Effects of staggered fermions and mixed actions on the scalar correlator

abstract:
  We provide the analytic predictions for the flavor non-singlet scalar
correlator, which will enable determination of the scalar meson mass from the
lattice scalar correlator. We consider simulations with 2+1 staggered sea
quarks and staggered or chiral valence quarks. At small u/d masses the
correlator is dominated by the bubble contribution, which is the intermediate
state with two pseudoscalar mesons. We determine the bubble contribution within
Staggered and Mixed Chiral Perturbation Theory.
  Its effective mass is smaller than the mass M_pi+M_eta, which is the lightest
intermediate state in proper 2+1 QCD. The unphysical effective mass is a
consequence of the taste breaking that makes possible the intermediate state
with mass 2*M_pi. We find that the scalar correlator can be negative in the
simulations with mixed quark actions if the sea and valence quark masses are
tuned by matching the pion masses M_{val,val}=M_{pi_5}.


title: 't Hooft loops and perturbation theory

abstract:
  We show that high-temperature perturbation theory describes extremely well
the area law of SU(N) spatial 't Hooft loops, or equivalently the tension of
the interface between different Z_N vacua in the deconfined phase. For SU(2),
the disagreement between Monte Carlo data and lattice perturbation theory for
sigma(T)/T^2 is less than 2%, down to temperatures O(10) T_c. For SU(N), N>3,
the ratios of interface tensions, (sigma_k/sigma_1)(T), agree with perturbation
theory, which predicts tiny deviations from the ratio of Casimirs, down to
nearly T_c. In contrast, individual tensions differ markedly from the
perturbative expression. In all cases, the required precision Monte Carlo
measurements are made possible by a simple but powerful modification of the
'snake' algorithm.


title: Diquark properties from lattice QCD

abstract:
  It has been argued recently that diquarks, a pair of quarks in the
anti-triplet representation of SU(3) color, are important building blocks of
baryons. The assumption that the scalar diquark is tightly bound seems to be
nicely accommodated by experimental data. In this paper I attempt to extract
phenomenological properties of diquarks from lattice QCD calculations. In
particular, I use the MILC 2+1 dynamical fermion lattices with domain wall
fermion valence quarks to probe diquarks very close to the chiral limit.


title: The pseudoparticle approach for solving path integrals in gauge theories

abstract:
  We present a numerical technique for calculating path integrals in
non-compact U(1) and SU(2) gauge theories. The gauge fields are represented by
a superposition of pseudoparticles of various types with their amplitudes and
color orientations as degrees of freedom. Applied to Maxwell theory this
technique results in a potential which is in excellent agreement with the
Coulomb potential. For SU(2) Yang-Mills theory the same technique yields clear
evidence of confinement. Varying the coupling constant exhibits the same
scaling behavior for the string tension, the topological susceptibility and the
critical temperature while their dimensionless ratios are similar to those
obtained in lattice calculations.


title:
The equation of state in lattice QCD: with physical quark masses towards
  the continuum limit

abstract:
  The equation of state of QCD at vanishing chemical potential as a function of
temperature is determined for two sets of lattice spacings. Coarser lattices
with temporal extension of N_t=4 and finer lattices of N_t=6 are used. Symanzik
improved gauge and stout-link improved staggered fermionic actions are applied.
The results are given for physical quark masses both for the light quarks and
for the strange quark. Pressure, energy density, entropy density, quark number
susceptibilities and the speed of sound are presented.


title: Pion form factors in two-flavor QCD

abstract:
  We present a calculation of pion electromagnetic and scalar form factors in
two-flavor QCD with the non-perturbatively O(a)-improved Wilson fermion. Chiral
extrapolation of the corresponding charge radius is discussed based on the
chiral perturbation theory.


title: Comparison of Chiral Fermion Methods

abstract:
  We present a comparison of various five-dimensional representations of chiral
fermions considering their cost and residual chiral symmetry breaking.


title: The QCD phase diagram at finite density

abstract:
  We study the density of states method to explore the phase diagram of the
chiral transition on the tempeature and quark chemical potential plane. Four
quark flavours are used in the analysis. Though the method is quite expensive
small lattices show an indication for a triple-point connecting three different
phases on the phase diagram.


title: Staggered Chiral Perturbation Theory for Heavy-Light Mesons

abstract:
  We incorporate heavy-light mesons into staggered chiral perturbation theory,
working to leading order in 1/m_Q, where m_Q is the heavy quark mass. At first
non-trivial order in the chiral expansion, staggered taste violations affect
the chiral logarithms for heavy-light quantities only through the light meson
propagators in loops. There are also new analytic contributions coming from
additional terms in the Lagrangian involving heavy-light and light mesons.
Using this heavy-light staggered chiral perturbation theory, we perform the
one-loop calculation of the B (or D) meson leptonic decay constant in the
partially quenched and full QCD cases. In our treatment, we assume the validity
both of the "fourth root trick" to reduce four staggered tastes to one, and of
the prescription to represent this trick in the chiral theory by insertions of
factors of 1/4 for each sea quark loop.


title: Second moment of the pion's distribution amplitude

abstract:
  We present preliminary results from the QCDSF/UKQCD collaborations for the
second moment of the pion's distribution amplitude with two flavours of
dynamical fermions. We use nonperturbatively determined renormalisation
coefficients to convert our results to the MSbar scheme at 5 GeV^2. Employing a
linear chiral extrapolation from our large pion masses >550 MeV, we find
<xi^2>=0.281(28), leading to a value of a_2=0.236(82) for the second Gegenbauer
moment.


title:
Operator product expansion and quark condensate from LQCD in coordinate
  space

abstract:
  We perform an exploratory study of the operator product expansion of the
quark propagator on the lattice at short distance in coordinate space. This
permits a simple determination of the quark condensate, <qq>^MS(2 GeV)=(-265\pm
5\pm 22 MeV)^3, and of the renormalization constant of the quark field, Z^MS(2
GeV)=0.871 \pm 0.003 \pm 0.020. This new method also provides a remarkable
non-perturbative test of the OPE predictions at short distance in QCD.


title:
Perturbative renormalization of the first moment of structure functions
  for domain-wall QCD

abstract:
  Using the domain-wall formulation of lattice fermions, we have computed the
one-loop renormalization factors of one-link operators which measure the first
nontrivial moment of the unpolarized, polarized and transversity structure
functions, in the flavor nonsinglet sector. The knowledge of these factors is
necessary in order to extract physical numbers from domain-wall Monte Carlo
simulations of parton distributions.
  We have automated the perturbative calculations by developing suitable FORM
codes. The results show that in many instances the total renormalization
factors are almost equal to one, and that hence the corresponding operators
are, for the appropriate values of the Dirac mass $M$ and the coupling $g_0$,
practically unrenormalized.


title:
Cutoff effects of Wilson fermions in the absence of spontaneous chiral
  symmetry breaking

abstract:
  We simulate two dimensional QED with two degenerate Wilson fermions and
plaquette gauge action. As a consequence of the Mermin-Wagner theorem, in the
continuum limit chiral symmetry is realized a la Wigner. This property affects
also the size of the cutoff effects. That can be understood in view of the fact
that the leading lattice artifacts are described, in the continuum Symanzik
effective theory, by chirality breaking terms. In particular, vacuum
expectation values of non-chirality-breaking operators are expected to be O(a)
improved in the chiral limit. We provide a numerical confirmation of this
expectation by performing a scaling test.


title: The screening length in hot QCD

abstract:
  We discuss the temperature dependence of the screening lengths in quenched
and full QCD using the non-perturbative lattice approach. We analyze the
temperature dependence of distances which are defined as moments of quark
antiquark free energies. These distance scales are supposed to describe the
geometric size of partonic clouds which screen static charges in a medium and
characterize distances beyond which the quark antiquark free energy is to large
extent dominated by medium effects. At asymptotic high temperatures these
moments can be related to the inverse Debye mass. In our numeric analysis we
find that these moments drop rapidly in the vicinity of the phase transition
and indicate distances which are about twice as large as the inverse Debye mass
found in earlier studies. Our analysis supports recent findings that indicate
that $J/\psi$ will show significant medium modifications only at temperatures
well above $T_c$.


title:
Static quark anti-quark free and internal energy in 2-flavor QCD and
  bound states in the QGP

abstract:
  We present results on heavy quark free energies in 2-flavour QCD. The
temperature dependence of the interaction between static quark anti-quark pairs
will be analyzed in terms of temperature dependent screening radii, which give
a first estimate on the medium modification of (heavy quark) bound states in
the quark gluon plasma. Comparing those radii to the (zero temperature) mean
squared charge radii of cha rmonium states indicates that the $J/\psi$ may
survive the phase transition as a bound state, while $\chi_c$ and $\psi'$ are
expected to show significant thermal modifications at temperatures close to the
transition. Furthermore we will analyze the relation between heavy quark free
energies, entropy contributions and internal energy and discuss their relation
to potential models used to analyze the melting of heavy quark bound states
above the deconfinement temperature. Results of different groups and various
potential models for bound states in the deconfined phase of QCD are compared.


title: Overlap fermion with the topology conserving gauge action

abstract:
  We investigate the distribution of low-lying eigenmodes of hermitian
Wilson-Dirac operator, $H_W$, with the gauge action whose form is designed to
avoid topology change, as well as with the standard plaquette action. On the
quenched lattices, the former gauge action exhibits less density of low-lying
eigenmodes of $H_W$ compared to the latter at the same lattice spacing. We also
show preliminary results for the dynamical simulation with two flavors of
overlap fermions.


title: Kaon B-parameter with NF=2 dynamical Wilson fermions

abstract:
  We present a preliminary study of the neutral kaon mixing bag parameter BK
using two flavors of dynamical Wilson fermions. We determine the matrix element
of the relevant DeltaS=2 operator by using both the conventional approach and
the so called ``non-subtraction method'', and find that the latter leads to
results with smaller uncertainties. After having implemented non-perturbative
renormalization, we study the dependence of BK on the see quark mass. At our
relatively heavy values of quark masses (0.60<M_P/M_V<0.75) such a dependence
is found to be negligible and the results, within the statistical accuracy, are
consistent with a quenched determination. As a preliminary result for the
renormalization group invariant parameter we quote BKRGI=1.02(25).


title:
Eigenmodes of covariant Laplacian in SU(2) Yang-Mills vacuum: higher
  representations

abstract:
  The study of lowest eigenmodes of the covariant Laplacian in fundamental
representation of the gauge group revealed their specific localization
properties. These may bear information on confinement of fundamental scalar
particles in SU(2) Yang-Mills vacuum. It was expected that scalar particle
eigenmodes in other representations would be localized in different physical
volumes. However simulations show strikingly different results for the adjoint
and higher (J=3/2) representations. Apart from much higher extent of
localization, we find evidence of different scaling behavior of localized
eigenmodes.


title:
Localization of Low Lying Eigenmodes for Chirally Symmetric Dirac
  Operator

abstract:
  We consider properties of zero and near-zero modes for overlap fermion
operator in SU(2) lattice gluodynamics. The density of the states is of the
order of Lambda(QCD) while the localization volume of the modes tends to zero
in physical units with the lattice spacing tending to zero. The situation
changes drastically when we study "vortex removed" configurations.


title:
Vortex Proliferation and the Dual Superconductor Scenario for
  Confinement: The 3D Compact U(1) Lattice Higgs Model

abstract:
  It is argued that the phase diagram of the 3D Compact U(1) Lattice Higgs
Model is more refined than generally thought. The confined and Higgs phases are
separated by a well-defined phase boundary, marked by proliferating vortices.
It is shown that the confinement mechanism at work is precisely the dual
superconductor scenario.


title: Transport Coefficient of Gluon Plasma from Lattice QCD

abstract:
  In this report we present our calculation of the transport coefficient of
gluon system on $24^3\times 8$ lattice in the quench approximation. Simulations
are carried out in the range, $1.4 \le T/T_c \le 24$. In the temperature region
slightly above the transition, where the perturbative calculation is not
applicable, the shear viscosity($\eta$) is smaller than typical hadron masses.
The bulk viscosity is consistent with zero within the range of error bars in
$1.4 \le T/T_c \le 24$. We compare our results with the perturbative
calculations in large $T/T_c$ region. It is found that the lattice and
perturbative results are consistent with each other there. The ratio $\eta/s$
is around $0.1-0.4$ in $T/T_c < 3$ region and satisfies the KSS
bound\cite{KSS}. In order to estimate the contribution from high frequency part
of the spectral function, we study the effects of a term $\rho^{high}$ proposed
by Aarts and Resco\cite{Aarts}. It is found that until the threshold mass
becomes small, its effect is quite small, and that viscosity decreases as the
threshold decreases. From these studies we think that although our result is
obtained under an assumptions for the spectral function, it gives a reasonable
estimation for $\eta$($=\pi d\rho/d\omega$ at $\omega=0$), and qualitative
results will not be changed when the accurate spectral function is obtained.


title: Loop States in Lattice Gauge Theories

abstract:
  We solve the Gauss law as well as the corresponding Mandelstam constraints of
(d+1) dimensional SU(2) lattice gauge theory in terms of harmonic oscillator
prepotentials. This enables us to explicitly construct a complete orthonormal
and manifestly gauge invariant basis in the physical Hilbert space. Further, we
show that this gauge invariant description represents networks of unoriented
loops carrying certain non-negative abelian fluxes created by the harmonic
oscillator prepotentials. The loop network is characterized by $3(d-1)$ gauge
invariant integers at every lattice site which is the number of physical
degrees of freedom. Time evolution involves local fluctuations of these loops.
The loop Hamiltonian is derived. The generalization to SU(N) gauge group is
discussed.


title:
Phase structure of lattice QCD with Wilson and Neuberger quarks at
  finite temperature and density

abstract:
  We review our results for lattice QCD at finite temperature and density from
analytical and numerical calculations with Wilson fermions and overlap
fermions.


title: Light-Quark FLIC Fermion Simulations of the $1^{-+}$ Exotic Meson

abstract:
  We investigate the mass of the $1^{-+}$ exotic meson, created with hybrid
interpolating fields. Access to light quark masses approaching 25 MeV is
facilitated by the use of the Fat-Link Irrelevant Clover (FLIC) fermion action,
and large ($20^3 \times 40$) lattices. Our results indicate that the $1^{-+}$
exotic exhibits significant curvature close to the chiral limit, and yield a
$1^{-+}$ mass in agreement with the $\pi_1 (1600)$ candidate and exclusive of
the $\pi_1 (1400)$.


title: Quantization of empty space

abstract:
  We suggest to use "minimal" choice of quantum gravity theory, that is the
quantum field theory, in which space-time is seen as Riemannian space and
metric (or vierbein field) is the dynamical variable. We then suggest to use
the simplest acceptable action, that is the squared curvature action. The
correspondent model is renormalizable, has the correct classical limit without
matter and can be explored using Euclidian path integral formalism. In order to
get nonperturbative results one has to put this model on the lattice. While
doing so serious problems with measure over dynamical variables are
encountered, which were not solved until present. We suggest to solve them
using the representation of Riemannian space as a limiting case of Riemann -
Cartan space, where the Poincare group connection plays the role of dynamical
variable. We construct manifestly gauge invariant discretization of Riemann -
Cartan space. Lattice realization of Poincare gauge transformation naturally
acts on the dynamical variables of the constructed discretization. There exists
local measure invariant under this gauge transformation, which could be used as
a basic element of lattice path integral methods. The correspondent lattice
model appears to be useful for numerical simulations.


title: Supercurrent Flow in NJL_{2+1} at High Baryon Density

abstract:
  We present results of numerical simulations of the 2+1d Nambu -- Jona-Lasinio
model with non-zero baryon chemical potential mu and spatially-varying complex
diquark source strength j. By choosing arg(j) to vary smoothly through 2 pi
across the spatial extent of the lattice, a baryon number current is induced
which in the high density phase remains non-vanishing as |j|->0; we are hence
able to extract a quantity characteristic of a superfluid known as the helicity
modulus. We also study supercurrent flow at non-zero temperature and estimate
the critical temperature at which the normal phase is restored, which is
consistent with the conventional picture for thin-film superfluids in which the
transition is viewed in terms of vortex -- anti-vortex unbinding.


title: Simulations in Early Universe Theory

abstract:
  We give an impression of the type of results that have been obtained with
numerical lattice simulations of field theory in the early universe.


title: On the effective string spectrum of the tridimensional Z(2) gauge model

abstract:
  We study the Z(2) lattice gauge theory in three dimensions, and present high
precision estimates for the first few energy levels of the string spectrum.
These results are obtained from new numerical data for the two-point Polyakov
loop correlation function, which is measured in the 3d Ising spin system using
duality. This allows us to perform a stringent comparison with the predictions
of effective string models. We find a remarkable agreement between the
numerical estimates and the Nambu-Goto predictions for the energy gaps at
intermediate and large distances. The precision of our data allows to
distinguish clearly between the predictions of the full Nambu-Goto action and
the simple free string model up to an interquark distance $r \approx
10/\sqrt{\sigma}$. At the same time, our results also confirm the breakdown of
the effective picture at short distances, supporting the hypothesis that terms
which are not taken into account in the usual Nambu-Goto string formulation
yield a non-trivial shift to the energy levels. Furthermore, we discuss the
theoretical implications of these results.


title:
Biased Metropolis-Heat-Bath Algorithm for Fundamental-Adjoint SU(2)
  Lattice Gauge Theory

abstract:
  For SU(2) lattice gauge theory with the fundamental-adjoint action an
efficient heat-bath algorithm is not known so that one had to rely on
Metropolis simulations supplemented by overrelaxation. Implementing a novel
biased Metropolis-heat-bath algorithm for this model, we find improvement
factors in the range 1.45 to 2.06 over conventionally optimized Metropolis
simulations. If one optimizes further with respect to additional overrelaxation
sweeps, the improvement factors are found in the range 1.3 to 1.8.


title:
Spectral properties of the Landau gauge Faddeev-Popov operator in
  lattice gluodynamics

abstract:
  Recently we reported on the infrared behavior of the Landau gauge gluon and
ghost dressing functions in SU(3) Wilson lattice gluodynamics with special
emphasis on the Gribov problem. Here we add an investigation of the spectral
properties of the Faddeev-Popov operator at $\beta$=5.8 and 6.2 for lattice
sizes 12^4, 16^4 and 24^4. The larger the volume the more of its eigenvalues
are found accumulated close to zero. Using the eigenmodes for the spectral
representation it turns out that for our smallest lattice O(200) eigenmodes are
sufficient to saturate the ghost propagator at lowest momentum. We associate
exceptionally large values of the ghost propagator to extraordinary
contributions of low-lying eigenmodes.


title: Quark-gluon vertex with an off-shell O(a)-improved chiral fermion action

abstract:
  We perform a study the quark-gluon vertex function with a quenched Wilson
gauge action and a variety of fermion actions. These include the domain wall
fermion action (with exponentially accurate chiral symmetry) and the Wilson
clover action both with the non-perturbatively improved clover coefficient as
well as with a number of different values for this coefficient. We find that
the domain wall vertex function behaves very well in the large momentum
transfer region. The off-shell vertex function for the on-shell improved clover
class of actions does not behave as well as the domain wall case and,
surprisingly, shows only a weak dependence on the clover coefficient $c_{SW}$
for all components of its Dirac decomposition and across all momenta. Including
off-shell improvement rotations for the clover fields can make this action
yield results consistent with those from the domain wall approach, as well as
helping to determine the off-shell improved coefficient $c_q^\prime$.


title: Non-perturbatively determined relativistic heavy quark action

abstract:
  Preliminary results are presented in a step scaling determination of the
coefficients in the relativistic heavy quark action. By matching finite volume,
heavy-heavy and heavy-light meson masses, we attempt to determine the four
parameters ($m$, $\zeta$, $c_B$ and $c_E$) in the on-shell-improved, heavy
quark action. In this report we carry out one step in this program by matching
two physically equivalent systems. The first is a fully relativistic
calculation using a $24^3\times 48$, $1/a=5.4$ GeV lattice with both the heavy
and light quarks treated as domain wall fermions. The second calculation uses
at $16^3\times 32$, $1/a=3.6$ GeV lattice, a domain-wall light quark and a
heavy quark computed with the relativistic heavy quark action. The four
parameters in this heavy quark effective action are then varied to reproduce
the mass spectrum from the first calculation. These calculations are carried
out in the quenched approximation for a heavy quark mass approximately that of
the charmed quark.


title: Dual superconducting properties of the QCD vacuum

abstract:
  A consistent description of the confining QCD vacuum as a dual superconductor
requires a determination of fundamental parameters such as the superconductor
correlation length $\xi$ and the field penetration depth $\lambda$, which
determine whether the superconductor is of type I or type II. We illustrate
preliminary results of a lattice determination of $\xi$ for the case of pure
Yang-Mills with two colors, obtained by measuring the temporal correlator of a
disorder parameter detecting dual superconductivity.


title:
Full determination of the CKM matrix using recent results from lattice
  QCD

abstract:
  A full determination of the CKM matrix using recent results from lattice QCD
is presented. To extract the CKM matrix in a uniform fashion, I exclusively use
results from unquenched lattice QCD as the theory input for nonperturbative QCD
effects. All 9 CKM matrix elements and all 4 Wolfenstein parameters are
obtained from results for gold-plated quantities, which include semileptonic
decay form factors and leptonic decay constants of B, D and K mesons, and
B^0-\bar{B}^0 and K^0-\bar{K}^0 mixing amplitudes.


title: Simulations of Cold Electroweak Baryogenesis

abstract:
  Cold Electroweak Baryogenesis is an attempt to explain the cosmological
baryon asymmetry using only a minimal extension of the Standard Model. The
relevant processes take place out of thermal equilibrium and are
non-perturbative, and so must be studied using full, real-time lattice
simulations. We present new results on the dependence on CP-violation and the
Higgs-to-W-mass ratio


title: Dirac eigenvalue correlations in quenched QCD at finite density

abstract:
  We compare eigenvalue correlations of the Dirac operator with a chemical
potential obtained from lattice simulations of quenched QCD with analytic
predictions obtained from chiral effective theories in the zero-momentum limit.
By comparing the density and two-point correlation function we show that the
analytic results agree with QCD at low energies. We also examine the scale
(Thouless energy) up to which the zero-momentum approximation is valid.


title: Topology conserving gauge action and the overlap-Dirac operator

abstract:
  We apply the topology conserving gauge action proposed by Luescher to the
four-dimensional lattice QCD simulation in the quenched approximation. With
this gauge action the topological charge is stabilized along the hybrid Monte
Carlo updates compared to the standard Wilson gauge action. The quark potential
and renormalized coupling constant are in good agreement with the results
obtained with the Wilson gauge action. We also investigate the low-lying
eigenvalue distribution of the hermitian Wilson-Dirac operator, which is
relevant for the construction of the overlap-Dirac operator.


title: Topology with Dynamical Overlap Fermions

abstract:
  We perform dynamical QCD simulations with $n_f=2$ overlap fermions by hybrid
Monte-Carlo method on $6^4$ to $8^3\times 16$ lattices. We study the problem of
topological sector changing. A new method is proposed which works without
topological sector changes. We use this new method to determine the topological
susceptibility at various quark masses.


title: The Sign Problem is the Solution

abstract:
  The unquenched spectral density of the Dirac operator at $\mu\neq0$ is
complex and has oscillations with a period inversely proportional to the volume
and an amplitude that grows exponentially with the volume. Here we show how the
oscillations lead to the discontinuity of the chiral condensate.


title: Chiral properties of dynamical Wilson fermions

abstract:
  We consider two-flavor QCD in the lattice regularization with improved Wilson
fermions. In this formulation chiral symmetry is explicitly broken at order a
and hence the isovector axial currents require improvement as well as a finite
renormalization if they are to satisfy continuum Ward--Takahashi identities up
to small lattice corrections of O(a^2). Algorithmic difficulties at coarse
lattice spacings, where HMC suffers from a distorted Dirac spectrum, are
discussed. This is shown to be a cutoff effect, which disappears rapidly as the
lattice spacing is decreased. An alternative algorithm, the polynomial hybrid
Monte Carlo algorithm, is found to perform significantly better in the presence
of exceptionally small eigenvalues. Extending previously used methods both the
improvement and the renormalization of the axial current are implemented
non--perturbatively in terms of correlation functions formulated in the
framework of the Schroedinger functional. In both cases this is achieved by
enforcing continuum Ward identities at finite lattice spacing. Together, this
restores the isovector chiral symmetry to quadratic order in the lattice
spacing. With little additional effort the normalization factor of the local
vector current is also obtained.


title: The onset and deconfinement transitions in two-colour QCD

abstract:
  We study two-colour QCD with two flavours of Wilson fermion at non-zero
chemical potential mu and zero temperature. We find evidence of two separate
transitions: an onset transition at mu ~ m_pi/2 where quark number and energy
densities increase from zero; and a deconfinement transition at higher mu. The
mu-dependence of the number and energy densities and the diquark condensate
indicate that a Fermi surface is formed and that BCS rather than Bose-Einstein
condensation dominates at the quark mass considered here, especially beyond the
deconfinement transition.


title: Twisted mass lattice QCD: Recent developments and results

abstract:
  I review recent theoretical developments and numerical results of twisted
mass QCD. I argue that, combined with an efficient algorithm, twisted mass QCD
can be an attractive QCD lattice action, to perform large scale simulations at
small pion masses, where a matching with chiral perturbation theory can be
performed. Open issues like flavour breaking effects are also addressed.


title: Localization and lattice fermions

abstract:
  I review how the phenomenology of localization applies to fermions in lattice
gauge theory, present measurements of the localization length and other
quantities, and discuss the consequences for things like the overlap kernel.


title: Chiral and Continuum Extrapolation of Partially-Quenched Hadron Masses

abstract:
  Using the finite-range regularisation (FRR) of chiral effective field theory,
the chiral extrapolation formula for the vector meson mass is derived for the
case of partially-quenched QCD. We re-analyse the dynamical fermion QCD data
for the vector meson mass from the CP-PACS collaboration. A global fit,
including finite lattice spacing effects, of all 16 of their ensembles is
performed. We study the FRR method together with a naive polynomial approach
and find excellent agreement ~1% with the experimental value of M_rho from the
former approach. These results are extended to the case of the nucleon mass.


title: Static-light hadrons on a dynamical anisotropic lattice

abstract:
  We present preliminary results for the static-light meson and baryon spectra
for $N_f=2$ QCD. The study is performed on an anisotropic lattice and uses a
new all-to-all propagator method allowing us to determine particle masses to a
high precision.


title: Asymptotic Scaling and Monte Carlo Data

abstract:
  It is a generally known problem that the behaviour predicted from
perturbation theory for asymptotically free theories like QCD, i.e. asymptotic
scaling, has not been observed in Monte Carlo simulations when the series is
expressed in terms of the bare coupling g_0. This discrepancy has been
explained in the past with the poor convergence properties of the perturbative
series in the g_0. An alternative point of view, called Lattice-Distorted
Perturbation Theory proposes that lattice artifacts due to the finiteness of
the lattice spacing, a, cause the disagreement between Monte Carlo data and
perturbative scaling. Following this alternative scenario, we fit recent
quenched data from different observables to fitting functions that include
these cut-off effects, confirming that the lattice data are well reproduced by
g_0-PT with the simple addition of terms O(a^n).


title: Scaling behavior of quark propagator in full QCD

abstract:
  We study the scaling behavior of the quark propagator on two lattices with
similar physical volume in Landau gauge with 2+1 flavors of dynamical quarks in
order to test whether we are close to the continuum limit for these lattices.
We use configurations generated with an improved staggered (``Asqtad'') action
by the MILC collaboration. The calculations are performed on $28^3\times 96$
lattices with lattice spacing $a = 0.09$ fm and on $20^3\times 64$ lattices
with lattice spacing $a = 0.12$ fm. We calculate the quark mass function,
$M(q^2)$, and the wave-function renormalization function, $Z(q^2)$, for a
variety of bare quark masses. Comparing the behavior of these functions on the
two sets of lattices we find that both $Z(q^2)$ and $M(q^2)$ show little
sensitivity to the ultraviolet cutoff.