12,356 research outputs found
ERG and Schwinger-Dyson Equations - Comparison in formulations and applications --
The advantageous points of ERG in applications to non-perturbative analyses
of quantum field theories are discussed in comparison with the Schwinger-Dyson
equations. First we consider the relation between these two formulations
specially by examining the large N field theories. In the second part we study
the phase structure of dynamical symmetry breaking in three dimensional QED as
a typical example of the practical applications.Comment: 13 pages, 6 figures, references are added. Invited talk presented at
Second Conference on the Exact RG, Sept 18 - 22, 2000, Rome, Ital
Isotropic and Anisotropic Lattice Spacing Corrections for I=2 pi-pi Scattering from Effective Field Theory
The calculation of the finite lattice spacing corrections for I=2 pi-pi
scattering is carried out for isotropic and anisotropic Wilson lattice actions.
Pion masses and decay constants are also determined in this context. These
results correct the phase shift calculated from the lattice, which is connected
to the scattering length and effective range in this low energy scattering
process. When in terms of the lattice-physical parameters for either Wilson
action, these lattice spacing effects first appear at the next-to-leading order
counter-terms.Comment: 15 pages, additional discussion of pion decay constant, version
published in PR
Surface modes and parity violation in Schwinger model on the lattice
The phase diagram of the Schwinger model on the lattice with Wilson fermions
is investigated in the Hartree-Fock approximation. In case of single flavour
(not directly amenable to simulations), the calculation indicates the existence
of the parity violating phase at both weak and intermediate-to-strong
couplings. Hartree-Fock vacuum sustains a nonzero electric field in this broken
phase. The phase structure of the model with two flavours is also discussed.Comment: 4 pages, uuencoded compressed PostScript (using uufiles),
contribution to LATTICE 9
Two-dimensional Lattice Gross-Neveu Model with Wilson Fermion Action at Finite Temperature and Chemical Potential
We investigate the phase structure of the two-dimensional lattice Gross-Neveu
model formulated with the Wilson fermion action to leading order of 1/N
expansion. Structural change of the parity-broken phase under the influence of
finite temperature and chemical potential is studied. The connection between
the lattice phase structure and the chiral phase transition of the continuum
theory is clarified.Comment: 42 pages, 20 EPS figures, using REVTe
Enhancement of field renormalization in scalar theories via functional renormalization group
The flow equations of the Functional Renormalization Group are applied to the
O(N)-symmetric scalar theory, for N=1 and N=4, in four Euclidean dimensions,
d=4, to determine the effective potential and the renormalization function of
the field in the broken phase. In our numerical analysis, the infrared limit,
corresponding to the vanishing of the running momentum scale in the equations,
is approached to obtain the physical values of the parameters by extrapolation.
In the N=4 theory a non-perturbatively large value of the physical
renormalization of the longitudinal component of the field is observed. The
dependence of the field renormalization on the UV cut-off and on the bare
coupling is also investigated.Comment: 20 pages, 7 figures. To appear in Physical Review
A fully-integrated 1.8-V, 2.8-W, 1.9-GHz, CMOS power amplifier
This paper demonstrated the first 2-stage, 2.8W, 1.8V, 1.9GHz fully-integrated DAT power amplifier with 50Ω input and output matching using 0.18Όm CMOS transistors. It has a small-signal gain of 27dB. The amplifier provides 2.8W of power into a 50Ω load with a PAE of 50%
Roles of axial anomaly on neutral quark matter with color superconducting phase
We investigate effects of the axial anomaly term with a chiral-diquark
coupling on the phase diagram within a two-plus-one-flavor Nambu-Jona-Lasinio
(NJL) model under the charge-neutrality and -equilibrium constraints. We
find that when such constraints are imposed, the new anomaly term plays a quite
similar role as the vector interaction does on the phase diagram, which the
present authors clarified in a previous work. Thus, there appear several types
of phase structures with multiple critical points at low temperature ,
although the phase diagrams with intermediate- critical point(s) are never
realized without these constraints even within the same model Lagrangian. This
drastic change is attributed to an enhanced interplay between the chiral and
diquark condensates due to the anomaly term at finite temperature; the u-d
diquark coupling is strengthened by the relatively large chiral condensate of
the strange quark through the anomaly term, which in turn definitely leads to
the abnormal behavior of the diquark condensate at finite , inherent to the
asymmetric quark matter. We note that the critical point from which the
crossover region extends to zero temperature appears only when the strength of
the vector interaction is larger than a critical value. We also show that the
chromomagnetic instability of the neutral asymmetric homogenous two-flavor
color superconducting(2CSC) phase is suppressed and can be even completely
cured by the enhanced diquark coupling due to the anomaly term and/or by the
vector interaction.Comment: 15 pages, 5 figures, typos corrected, new references and some
statements adde
Full QCD Light Hadron Spectrum and Quark Masses: Final Results from CP-PACS
We present the final results of the CP-PACS calculation of the light hadron
spectrum and quark masses with two flavors of dynamical quarks. Simulations are
made with a renormalization-group improved gauge action and a mean-field
improved clover quark action for sea quark masses corresponding to --0.6 and the lattice spacing --0.11 fm. For
the meson spectrum in the continuum limit a clearly improved agreement with
experiment is observed compared to the quenched case, demonstrating the
importance of sea quark effects. For light quark masses we obtain
MeV and
MeV (-input) and
MeV (-input), which are reduced by
about 25% compared to the values in quenched QCD.Comment: Lattice 2000 (Spectrum), 4 pages, 3 figure
Non-Perturbative Determination of in Three-flavor Dynamical QCD
We present a fully non-perturbative determination of the improvement
coefficient in three-flavor dynamical QCD for the RG improved as
well as the plaquette gauge actions, using the Schr\"odinger functional scheme.
Results are compared with one-loop estimates at weak gauge coupling.Comment: 3 pages, 6 figures, Lattice2002(Improvement and Renormalization),
Unnecessary files are remove
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