101,439 research outputs found
The QCD vacuum as a disordered medium: A simplified model for the QCD Dirac operator
We model the QCD Dirac operator as a power-law random banded matrix (RBM)
with the appropriate chiral symmetry. Our motivation is the form of the Dirac
operator in a basis of instantonic zero modes with a corresponding gauge
background of instantons. We compare the spectral correlations of this model to
those of an instanton liquid model (ILM) and find agreement well beyond the
Thouless energy. In the bulk of the spectrum the (dimensionless) Thouless
energy of the RBM scales with the square root of system size in agreement with
the ILM and chiral perturbation theory. Near the origin the scaling of the
(dimensionless) Thouless energy in the RBM remains the same as in the bulk
which agrees with chiral perturbation theory but not with the ILM. Finally we
discuss how this RBM should be modified in order to describe the spectral
correlations of the QCD Dirac operator at the finite temperature chiral
restoration transition.Comment: 4 pages, 3 figure
Neutrino Masses and Mixing: Where We Stand and Where We are Going
In this talk I review our present knowledge on neutrino masses and mixing as
well as the expectations from near future experiments.Comment: 19 Pages, 11 figures. Review talk given at the 10th International
Conference on Supersymmetry and Unification of Fundamental Interactions,
SUSY02 (June 17-23, 2002, DESY, Hamburg
Impact of two mass-scale oscillations on the analysis of atmospheric and reactor neutrino data
We study the stability of the results of 3-nu oscillation analysis of
atmospheric and reactor neutrino data under departures of the one--dominant
mass scale approximation. In order to do so we perform the analysis of
atmospheric and reactor neutrino data in terms of three--neutrino oscillations
where the effect of both mass differences is explicitly considered. We study
the allowed parameter space resulting from this analysis as a function of the
mass splitting hierarchy parameter alpha = Delta m^2/Delta M^2 which
parametrizes the departure from the one--dominant mass scale approximation. We
consider schemes with both direct and inverted mass ordering. Our results show
that in the analysis of atmospheric data the derived range of the largest mass
splitting, Delta M^2$, is stable while the allowed ranges of mixing angles
sin^2 theta_{23} and sin^2 theta_{13} are wider than those obtained in the
one--dominant mass scale approximation. Inclusion of the CHOOZ reactor data in
the analysis results into the reduction of the parameter space in particular
for the mixing angles. As a consequence the final allowed ranges of parameters
from the combined analysis are only slightly broader than when obtained in the
one--dominant mass scale approximation.Comment: Updated data, references added and typos corrected. Version to appear
in Eur.Phys.J.
Status of Global Analysis of Neutrino Oscillation Data
In this talk we discuss some details of the analysis of neutrino data and our
present understanding of neutrino masses and mixing. This talk is based on
hep-ph/0306001, hep-ph/0306226 and hep-ph/0404085.Comment: 10 pages, LaTeX file using ws-procs9x6, 6 figures included. Talk
given by MCGG at the 5th Workshop on "Neutrino Oscillations and their Origin"
(NOON2004), Tokyo, Japan, February 11-15, 200
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