1,368 research outputs found
A First Taste of Dynamical Fermions with an O(a) Improved Action
We present the first results obtained by the UKQCD Collaboration using a
non-perturbatively improved Wilson quark action with two degenerate
dynamical flavours.Comment: Talk presented at Lattice '97, Edinburgh (UK), July 1997. LaTeX 3
pages, uses espcrc2, 3 figure
Thermodynamics with Dynamical Clover Fermions
We investigate the finite temperature behavior of nonperturbatively improved
clover fermions on lattices with temporal extent N_t=4 and 6. Unfortunately in
the gauge coupling range, where the clover coefficient has been determined
nonperturbatively, the finite temperature crossover/transition occurs at heavy
pseudoscalar masses and large pseudoscalar to vector meson mass ratios.
However, on an N_t=6 lattice the thermal crossover for the improved fermions is
much smoother than for unimproved Wilson fermions and no strange metastable
behavior is observed.Comment: 8 pages, LaTeX, 5 postscript figure
Speeding up the HMC: QCD with Clover-Improved Wilson Fermions
We apply a recent proposal to speed up the Hybrid-Monte-Carlo simulation of
systems with dynamical fermions to two flavor QCD with clover-improvement. For
our smallest quark masses we see a speed-up of more than a factor of two
compared with the standard algorithm.Comment: 3 pages, lattice2002, algorithms, DESY Report-no correcte
Trees whose 2-domination subdivision number is 2
A set of vertices in a graph is a -dominating set if every vertex of is adjacent to at least two vertices of . The -domination number of a graph , denoted by , is the minimum size of a -dominating set of . The -domination subdivision number is the minimum number of edges that must be subdivided (each edge in can be subdivided at most once) in order to increase the -domination number. The authors have recently proved that for any tree of order at least , . In this paper we provide a constructive characterization of the trees whose -domination subdivision number is
Ferrofluid convective heat transfer under the influence of external magnetic source
AbstractFerrofluid convective heat transfer in a cavity with sinusoidal cold wall is examined under the influence of external magnetic source. The working fluid is Fe3O4-water nanofluid. Single phase model is used to estimate the behavior of nanofluid. Vorticity stream function formulation is utilized to eliminate pressure gradient source terms. New numerical method is chosen namely Control volume base finite element method. Influences of Rayleigh, Hartmann numbers, amplitude of the sinusoidal wall and volume fraction of Fe3O4 on hydrothermal characteristics are presented. Results indicate that temperature gradient enhances as space between cold and hot walls reduces at low buoyancy force. Lorentz forces cause the nanofluid velocity to reduce and augment the thermal boundary layer thickness. Nusselt number augments with rise of buoyancy forces but it decreases with augment of Lorentz forces
The D234 action for light quarks
We investigate a new light fermion action (the ``D234'' action), which is
accurate up to \O(a^3) and tadpole-improved \O(a \alpha_s) errors. Using
D234 with Symanzik- and tadpole-improved glue we find evidence that continuum
results for the quenched hadron spectrum (pion, rho and nucleon) can be
obtained on coarse lattices.Comment: Latex, 4 pages, submitted to Lattice '95 proceeding
The Signed Roman Domatic Number of a Digraph
Let be a finite and simple digraph with vertex set .A {\em signed Roman dominating function} on the digraph isa function such that for every , where consists of andall inner neighbors of , and every vertex for which has an innerneighbor for which . A set of distinct signedRoman dominating functions on with the property that for each, is called a {\em signed Roman dominating family} (of functions) on . The maximumnumber of functions in a signed Roman dominating family on is the {\em signed Roman domaticnumber} of , denoted by . In this paper we initiate the study of signed Romandomatic number in digraphs and we present some sharp bounds for . In addition, wedetermine the signed Roman domatic number of some digraphs. Some of our results are extensionsof well-known properties of the signed Roman domatic number of graphs
Comparing Wilson and Clover Quenched Spectroscopy with an Improved Gauge Action
We present results of quenched hadron spectroscopy comparing
\order(a) improved Wilson (Clover) fermions with conventional Wilson
fermions. The configurations were generated using an \order(a^2) improved
6-link pure gauge action at 's corresponding to lattice spacings
of , , , , and fm. We find evidence that
fermionic scaling violations are consistent with \order(a^2) for Clover and
\order(a) with a nonnegligible \order(a^2) term for standard Wilson
fermions. This latter mixed ansatz makes a reliable continuum extrapolation
problematic for Wilson fermions. We also find that the slope of the scaling
violations is roughly for both Wilson and Clover fermions.Comment: 3 pages latex with 2 postscript figures. Talk presented at
LATTICE96(spectrum
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