20,434 research outputs found
Fermion Modes in Instanton-Anti-Instanton Background in (1+0)-dimensional Model
We evaluate the eigenvalues of Dirac operator in the background of
instanton-anti-instanton configuration (I-), in a simple
(1+0)-dimensional model, and find that quasi-zero-mode disappears for the
closely localized I- configurations. This result suggests that
the configurations which are dominant at high energy in the valley method are
actually non-anomalous ones and irrelevant to fermion number violation. Hence,
there seems to be no theoretical basis for expecting anomalous cross section to
become observable at energies of 10 Tev region in Weinberg-Salam theory.Comment: LaTeX, 7 pages 7 figures available on request, UT-65
Baryon-Baryon Interactions from Lattice QCD
We report on new attempt to investigate baryon-baryon interactions in lattice
QCD. From the Bethe-Salpeter (BS) wave function, we have successfully extracted
the nucleon-nucleon () potentials in quenched QCD simulations, which
reproduce qualitative features of modern potentials. The method has been
extended to obtain the tensor potential as well as the central potential and
also applied to the hyperon-nucleon () interactions, in both quenched and
full QCD.Comment: 6 pages, 10 figures, A plenary talk given at the 5-th International
Conference on Quark and Nuclear Physics, Beijing, September 21-26, 200
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
Manifestation of spin degrees of freedom in the double fractional quantum Hall system
The double fractional quantum Hall system of spin 1/2 electrons is
numerically studied to predict that there exists a novel spin-unpolarized
quantum liquid specific to the multi-species system, which exemplifies a link
between the spin state and the inter-layer electron correlation. Even when the
ground state is spin-polarized, the lowest charge-excitation mode involves the
spin when the interlayer tunneling is considered.Comment: typeset in LATEX, 2 figures available upon request at
[email protected], 9 pages, NA-94-0
Cost of dynamical quark simulations: O(a) improved Wilson fermions
I report on cost estimates and algorithmic performance in simulations using 2
flavours of non-perturbatively O(a) improved Wilson quarks together with the
Wilson plaquette action.Comment: Contribution to Lattice2001 (panel discussion), 2 pages, 2 figure
Tau polarization effects in the CNGS tau-neutrino appearance experiments
We studied tau polarization effects on the decay distributions of tau
produced in the CNGS tau-neutrino appearance experiments. We show that energy
and angular distributions for the decay products in the laboratory frame are
significantly affected by the tau polarization. Rather strong azimuthal
asymmetry about the tau momentum axis is predicted, which may have observable
consequences in experiments even with small statistics.Comment: 5 pages, 6 eps figures, espcrc2.sty; Proceedings of the 4th
International Workshop on Neutrino-Nucleus Interactions in the Few GeV Region
(NuInt05), September 26-29, 2005, Okayama, Japa
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