104,863 research outputs found
Duality Breaking of Vortex Configuration in a Hierarchical Honeycomb Network
We report measurements of Little-Parks oscillation on the hierarchical
honeycomb-superconducting network for investigating possible effects of
hierarchical structure in terms of spatial symmetry, parity and duality. We
observed an asymmetric Little-Parks oscillation about ,
although spatial symmetry was kept in the network. In comparison with a regular
honeycomb network, the asymmetric oscillation is attributed to hierarchy which
induces mixture of commensurate and incommensurate regions. The asymmetric
oscillation is found to indicate breaking of the duality of vortex
configuration.Comment: 12 pages, 6 figure
Leptogenesis within a generalized quark-lepton symmetry
Quark-lepton symmetry has been shown to be inconsistent with baryogenesis via
leptogenesis in natural schemes of the see-saw mechanism. Within the
phenomenological approach of textures, we relax this strict symmetry and
propose weaker conditions, namely models of the neutrino Dirac mass matrix
which have the same hierarchy as the matrix elements of . We call
this guide-line generalized quark-lepton symmetry. We consider
in detail particular cases in which the moduli of the matrix elements of
are equal to those of . Within the phenomenological approach of textures,
we try for the heavy Majorana mass matrix diagonal and off-diagonal forms. We
find that an ansatz for preserving the hierarchy, together with an
off-diagonal model for the heavy Majorana neutrino mass, is consistent with
neutrino masses, neutrino mixing and baryogenesis via leptogenesis for an
intermediate mass scale GeV. The preservation of the
hierarchical structure could come from a possible symmetry scheme.Comment: 12 pages, RevTex4. Title and abstract changed. Revised and enlarged
versio
Large Lepton Mixings from Continuous Symmetries
Within the broad context of quark-lepton unification, we investigate the
implications of broken continuous family symmetries which result from requiring
that in the limit of exact symmetry, the Dirac mass matrices yield hierarchical
masses for the quarks and charged leptons, but lead to degenerate light
neutrino masses as a consequence of the seesaw mechanism, without requiring
hierarchical right-handed neutrino mass terms. Quark mixing is then naturally
small and proportional to the size of the perturbation, but lepton mixing is
large as a result of degenerate perturbation theory, shifted from maximal
mixing by the size of the perturbation. Within this approach, we study an
illustrative two-family prototype model with an SO(2) family symmetry, and
discuss extensions to three-family models.Comment: 23 page
A Quantitative Clustering Approach to Ultrametricity in Spin Glasses
We discuss the problem of ultrametricity in mean field spin glasses by means
of a hierarchical clustering algorithm. We complement the clustering approach
with quantitative testing: we discuss both in some detail. We show that the
elimination of the (in this context accidental) spin flip symmetry plays a
crucial role in the analysis, since the symmetry hides the real nature of the
data. We are able to use in the analysis disorder averaged quantities. We are
able to exhibit a number of features of the low phase of the mean field
theory, and to claim that the full hierarchical structure can be observed
without ambiguities only on very large lattice volumes, not currently
accessible by numerical simulations.Comment: 15 pages with color figure
Symmetry Breaking Bulk Effects in Local D-brane Models
We study symmetry breaking effects in local D-brane models that arise as a
result of compactification, taking models constructed on C^3/Z_3 as prototype.
Zero-modes of the Lichnerowicz operator in cone-like geometries have a power
law behaviour; thus the leading symmetry breaking effects are captured by the
modes with the lowest scaling dimension which transform non-trivially under the
isometry group. Combining this with the fact that global symmetries in local
models are gauged upon compactification we determine the strength and form of
the leading operators responsible for the symmetry breaking. We find a
hierarchical separation in the size of symmetry breaking parameters.Comment: 13 pages, 1 figure; v2 typos removed; v3 JHEP versio
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