12,610 research outputs found
One loop renormalization for the axial Ward-Takahashi identity in Domain-wall QCD
We calculate one-loop correction to the axial Ward-Takahashi identity given
by Furman and Shamir in domain-wall QCD. It is shown perturbatively that the
renormalized axial Ward-Takahashi identity is satisfied without fine tuning and
the ``conserved'' axial current receives no renormalization, giving .
This fact will simplify the calculation of the pion decay constant in numerical
simulations since the decay constant defined by this current needs no lattice
renormalization factor.Comment: 16 pages, 3 axodraw.sty figure
Electronic structure of an electron on the gyroid surface, a helical labyrinth
Previously reported formulation for electrons on curved periodic surfaces is
used to analyze the band structure of an electron bound on the gyroid surface
(the only triply-periodic minimal surface that has screw axes). We find that an
effect of the helical structure appears as the bands multiply sticking together
on the Brillouin zone boundaries. We elaborate how the band sticking is lifted
when the helical and inversion symmetries of the structure are degraded. We
find from this that the symmetries give rise to prominent peaks in the density
of states.Comment: RevTeX, 4 pages, 6 figure
Interpolation between the epsilon and p regimes
We reconsider chiral perturbation theory in a finite volume and develop a new
computational scheme which smoothly interpolates the conventional epsilon and p
regimes. The counting rule is kept essentially the same as in the p expansion.
The zero-momentum modes of Nambu-Goldstone bosons are, however, treated
separately and partly integrated out to all orders as in the epsilon expansion.
In this new scheme, the theory remains infra-red finite even in the chiral
limit, while the chiral-logarithmic effects are kept present. We calculate the
two-point function in the pseudoscalar channel and show that the correlator has
a constant contribution in addition to the conventional hyperbolic cosine
function of time t. This constant term rapidly disappears in the p regime but
it is indispensable for a smooth convergence of the formula to the epsilon
regime result. Our calculation is useful to precisely estimate the finite
volume effects in lattice QCD simulations on the pion mass Mpi and kaon mass
MK, as well as their decay constants Fpi and FK.Comment: 49 pages, 6 figures, minor corrections, references added, version to
appear in PR
Exact supersymmetry in the relativistic hydrogen atom in general dimensions -- supercharge and the generalized Johnson-Lippmann operator
A Dirac particle in general dimensions moving in a 1/r potential is shown to
have an exact N = 2 supersymmetry, for which the two supercharge operators are
obtained in terms of (a D-dimensional generalization of) the Johnson-Lippmann
operator, an extension of the Runge-Lenz-Pauli vector that relativistically
incorporates spin degrees of freedom. So the extra symmetry (S(2))in the
quantum Kepler problem, which determines the degeneracy of the levels, is so
robust as to accommodate the relativistic case in arbitrary dimensions.Comment: 4 pages, 1 figur
A lagrangian approach to weakly coupled Hamilton-Jacobi systems
We study a class of weakly coupled Hamilton–Jacobi systems with a specific
aim to perform a qualitative analysis in the spirit of weak KAM theory. Our main
achievement is the definition of a family of related action functionals containing the
Lagrangians obtained by duality from the Hamiltonians of the system. We use them to
characterize, by means of a suitable estimate, all the subsolutions of the system, and
to explicitly represent some subsolutions enjoying an additional maximality property. A
crucial step for our analysis is to put the problem in a suitable random frame. Only
some basic knowledge of measure theory is required, and the presentation is accessible
to readers without background in probability
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
Domain Wall Fermions in Quenched Lattice QCD
We study the chiral properties and the validity of perturbation theory for
domain wall fermions in quenched lattice QCD at beta=6.0. The explicit chiral
symmetry breaking term in the axial Ward-Takahashi identity is found to be very
small already at Ns=10, where Ns is the size of the fifth dimension, and its
behavior seems consistent with an exponential decay in Ns within the limited
range of Ns we explore. From the fact that the critical quark mass, at which
the pion mass vanishes as in the case of the ordinary Wilson-type fermion,
exists at finite Ns, we point out that this may be a signal of the parity
broken phase and investigate the possible existence of such a phase in this
model at finite Ns. The rho and pi meson decay constants obtained from the
four-dimensional local currents with the one-loop renormalization factor show a
good agreement with those obtained from the conserved currents
Dynamical scaling analysis of the optical Hall conductivity in the quantum Hall regime
Dynamical scaling analysis is theoretically performed for the ac (optical)
Hall conductivity as a function of Fermi
energy and frequency for the two-dimensional electron
gas and for graphene. In both systems, results based on exact diagonalization
show that displays a well-defined dynamical
scaling, for which the dynamical critical exponent as well as the localization
exponent are fitted and plugged in. A crossover from the dc-like bahavior to
the ac regime is identified. The dynamical scaling analysis has enabled us to
quantify the plateau in the ac Hall conductivity previously obtained, and to
predict that the plateaux structure in ac is robust enough to be observed in
the THz regime.Comment: 5 pages, 3 figure
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