11 research outputs found
Impact of the finite volume effects on the chiral behavior of fK and BK
We discuss the finite volume corrections to fK and BK by using the one-loop
chiral perturbation theory in full, quenched, and partially quenched QCD. We
show that the finite volume corrections to these quantities dominate the
physical (infinite volume) chiral logarithms.Comment: 16 pages, 3 figures [published version
Domain wall fermion and chiral gauge theories on the lattice with exact gauge invariance
We discuss how to construct anomaly-free chiral gauge theories on the lattice
with exact gauge invariance in the framework of domain wall fermion. Chiral
gauge coupling is realized by introducing a five-dimensional gauge field which
interpolates between two different four-dimensional gauge fields at boundaries.
The five-dimensional dependence is compensated by a local and gauge-invariant
counter term. The cohomology problem to obtain the counter term is formulated
in 5+1 dimensional space, using the Chern-Simons current induced from the
five-dimensional Wilson fermion. We clarify the connection to the invariant
construction based on the Ginsparg-Wilson relation using overlap Dirac
operator. Formula for the measure and the effective action of Weyl fermions are
obtained in terms of five-dimensional lattice quantities.Comment: 46 pages, LaTeX, references added and updated, minor text correction
Lattice calculation of hybrid mesons with improved Kogut-Susskind fermions
We report on a lattice determination of the mass of the exotic
hybrid meson using an improved Kogut-Susskind action. Results from both
quenched and dynamical quark simulations are presented. We also compare with
earlier results using Wilson quarks at heavier quark masses. The results on
lattices with three flavors of dynamical quarks show effects of sea quarks on
the hybrid propagators which probably result from coupling to two meson states.
We extrapolate the quenched results to the physical light quark mass to allow
comparison with experimental candidates for the hybrid meson. The
lattice result remains somewhat heavier than the experimental result, although
it may be consistent with the .Comment: 24 pages, 12 figures. Replaced to match published versio
B-->pi and B-->K transitions in standard and quenched chiral perturbation theory
We study the effects of chiral logs on the heavy-->light pseudoscalar meson
transition form factors by using standard and quenched chiral perturbation
theory combined with the static heavy quark limit. The resulting expressions
are used to indicate the size of uncertainties due to the use of the quenched
approximation in the current lattice studies. They may also be used to assess
the size of systematic uncertainties induced by missing chiral log terms in
extrapolating toward the physical pion mass. We also provide the coefficient
multiplying the quenched chiral log, which may be useful if the quenched
lattice studies are performed with very light mesons.Comment: 33 pages, 8 PostScript figures, version to appear in PR
Chemical and isotopic switching within the subglacial environment of a high Arctic glacier.
Natural environmental isotopes of nitrate, sulphate and inorganic carbon are discussed in conjunction with major ion chemistry of subglacial runoff from a High Arctic glacier, Midre Lovénbreen, Svalbard. The chemical composition of meltwaters is observed to switch in accordance with subglacial hydrological evolution and redox status. Changing rapidly from reducing to oxidizing conditions, subglacial waters also depict that 15N/14N values show microbial denitrification is an active component of nutrient cycling beneath the glacier. 18O/16O ratios of sulphate are used to elucidate mechanisms of biological and abiological sulphide oxidation. Concentrations of bicarbonate appear to be governed largely by the degree of rock:water contact encountered in the subglacial system, rather than the switch in redox status, although the potential for microbiological activity to influence ambient bicarbonate concentrations is recognised. Glaciers are therefore highlighted as cryospheric ecosystems supporting microbial life which directly impacts upon the release of solute through biogeochemically mediated processes