395 research outputs found
Heavy-Light Decay Constants: Conclusions from the Wilson Action
We report on the results of a MILC collaboration calculation of ,
, , and their ratios. We discuss the most important
errors in more detail than we have elsewhere.Comment: LATTICE98(heavyqk) 3 latex pages and 3 postscript figures. The
perturbative correction calculated by Kuramashi has been adjusted to take
into account the fact that we match to the continuum at the kinetic mass of
the heavy meson, not the pole mass. This produces a 2 to 4 MeV change in
final results for decay constants, and has negligible effect on decay
constant ratio
Kink interactions in
There are classes of kink solutions in . We show how
interactions between various kinks depend on the classes of individual kinks as
well as on their orientations with respect to each other in the internal space.
In particular, we find that the attractive or repulsive nature of the
interaction depends on the trace of the product of charges of the two kinks. We
calculate the interaction potential for all combinations of kinks and antikinks
in and study their collisions. The outcome of kink-antikink
collisions, as expected from previous studies, is sensitive to their initial
relative velocity. We find that heavier kinks tend to break up into lighter
ones, while interactions between the lightest kinks and antikinks in this model
can be repulsive as well as attractive.Comment: 11 pages, 9 figures. Two insignificant sign errors corrected in the
revised versio
The equation of state for two flavor QCD
We improve the calculation of the equation of state for two flavor QCD by
simulating on lattices at appropriate values of the couplings for the
deconfinement/chiral symmetry restoration crossover. For the
energy density rises rapidly to approximately 1 just after the
crossover( at this point). Comparing with our previous
result for ~\cite{eos}, we find large finite corrections as
expected from free field theory on finite lattices. We also provide formulae
for extracting the speed of sound from the measured quantities.Comment: Contribution to Lattice 95 proceedings (combines talks presented by
T. Blum and L. Karkkainen). LaTeX, 8 pages, uses espcrc2.sty, postscript
figures include
Critical Behavior at the Chiral Phase Transition
Quantum chromodynamics with two zero mass flavors is expected to exhibit a
phase transition with O(4) critical behavior. Fixing the universality class is
important for phenomenology and for facilitating the extrapolation of
simulation data to physical quark mass values. At Lattice '96 the Tsukuba and
Bielefeld groups reported results from new simulations with dynamical staggered
quarks at , which suggested a departure from the expected critical
behavior. We report observations of similar deviations and discuss efforts in
progress to understand this phenomenon.Comment: 3 pp, LaTeX with 6 encapsulated Postscript figures. Lattice '97
proceeding
Properties of the a1 Meson from Lattice QCD
We determine the mass and decay constant of the meson using Monte Carlo
simulation of lattice QCD. We find MeV and , in good agreement with experiment.Comment: 9 page uu-encoded compressed postscript file. version appearing in
Phys. Rev. Lett. 74 (1995) 459
High-Precision Lattice QCD Confronts Experiment
We argue that high-precision lattice QCD is now possible, for the first time,
because of a new improved staggered quark discretization. We compare a wide
variety of nonperturbative calculations in QCD with experiment, and find
agreement to within statistical and systematic errors of 3% or less. We also
present a new determination of alpha_msbar(Mz); we obtain 0.121(3). We discuss
the implications of this breakthrough for phenomenology and, in particular, for
heavy-quark physics.Comment: 2 figures, revte
Thermodynamics for two flavor QCD
We conclude our analysis of the N_t=6 equation of state for two flavor QCD,
first described at last year's conference. We have obtained new runs at
am_q=0.025 and improved runs at am_q=0.0125. The results are extrapolated to
m_q=0, and we extract the speed of sound as well. We also present evidence for
a restoration of the SU(2) X SU(2) chiral symmetry just above the crossover,
but not of the axial U(1) chiral symmetry.Comment: Poster presented at LATTICE96(finite temperature). 4 pages, LaTeX
plus 5 encapsulated Postscript figure
The continuum limit in the quenched approximation
Previous work at with quenched staggered quarks is extended with
new calculations at 5.85 and 6.15 on lattices up to . These
calculations allow a more detailed study of extrapolation in quark mass, finite
volume and lattice spacing than has heretofore been possible. We discuss how
closely the quenched spectrum approaches that of the real world.Comment: 4 pages, uuencoded compressed PostScript, contribution to Lattice '9
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