3,703 research outputs found
Lambda-parameter of lattice QCD with Symanzik improved gluon actions
We compute the ratio Lambda_L/Lambda_MS, where the scale parameter Lambda_L
is associated with a lattice formulation of QCD. We consider a 3-parameter
family of gluon actions, which are most frequently used for O(a) improvement a`
la Symanzik. The gluon action is put togeter with standard discretizations for
fermions (Wilson/clover, overlap), to provide Lambda_L for several possible
combinations of fermion and gluon actions. We employ the background field
technique in order to calculate the 1PI 2-point function of the background
field; this leads to the coupling constant renormalization function, Z_g, at
1-loop level.
Our results are obtained for an extensive range of values for the Symanzik
coefficients.Comment: 11 pages, 3 figures, 3 table
Temperature variation of the resistivity of metallic strain gauge materials Final report
Temperature effects on electrical resistivity of metallic strain gage material
One-Loop Self Energy and Renormalization of the Speed of Light for some Anisotropic Improved Quark Actions
One-loop corrections to the fermion rest mass M_1, wave function
renormalization Z_2 and speed of light renormalization C_0 are presented for
lattice actions that combine improved glue with clover or D234 quark actions
and keep the temporal and spatial lattice spacings, a_t and a_s, distinct. We
explore a range of values for the anisotropy parameter \chi = a_s/a_t and treat
both massive and massless fermions.Comment: 45 LaTeX pages with 4 postscript figure
The Lattice Parameter in Domain Wall QCD
We evaluate the ratio of the scale parameter in domain wall QCD to
the one in the continuum theory at one loop level incorporating the effect of
massless quarks. We show that the Pauli-Villars regulator is required to
subtract the unphysical massive fermion modes which emerge in the fermion loop
contributions to the gluon self energy. Detailed results are presented as a
function of the domain wall height .Comment: 16 pages, 1 figure as eps-file, some references adde
Perturbative Renormalization Factors of Bilinear Quark Operators for Improved Gluon and Quark Actions in Lattice QCD
We calculate one-loop renormalization factors of bilinear quark operators for
gluon action including six-link loops and -improved quark action in the
limit of massless quark. We find that finite parts of one-loop coefficients of
renormalization factors diminish monotonically as either of the coefficients
or of the six-link terms are decreased below zero. Detailed
numerical results are given, for general values of the clover coefficient, for
the tree-level improved gluon action in the Symanzik approach and for the choices suggested by Wilson and by Iwasaki and from renormalization-group analyses. Compared with the case of
the standard plaquette gluon action, finite parts of one-loop coefficients are
reduced by 10--20% for the Symanzik action, and approximately by a factor two
for the renormalization-group improved gluon actions.Comment: 19 pages, REVTeX, with 3 epsf figure
The SU(3) deconfining phase transition with Symanzik action
We report on the determination of the deconfining temperature in SU(3) pure
gauge theory, using the Symanzik tree level improved action, on lattices of
size 3 x 12^3, 4 x 16^3, 5 x 20^3, 6 x24^3. We find that the asymptotic scaling
violation pattern is similar to the one observed using the Wilson action. We
conclude that the irrelevant operators do not affect, in the range of couplings
considered, the lattice beta function. An analysis based on an effective
coupling formulation shows an apparent improvement.Comment: 8 pages, report IFUP-TH 12/9
Perturbative calculation of improvement coefficients to O(g^2a) for bilinear quark operators in lattice QCD
We calculate the O(g^2 a) mixing coefficients of bilinear quark operators in
lattice QCD using a standard perturbative evaluation of on-shell Green's
functions. Our results for the plaquette gluon action are in agreement with
those previously obtained with the Schr\"odinger functional method. The
coefficients are also calculated for a class of improved gluon actions having
six-link terms.Comment: 14 pages, REVTe
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