5,593 research outputs found
Search for a Lorentz invariance violation in atmospheric neutrino oscillations using MACRO data
The energy spectrum of neutrino-induced upward-going muons in MACRO was
analysed in terms of special relativity principles violating effects, keeping
standard mass-induced atmospheric neutrino oscillations as the dominant source
of nu_mu nu_tau transitions. The data disfavour these exotic possibilities
even at a sub-dominant level, and stringent 90% C.L. limits are placed on the
Lorentz invariance violation parameters. These limits can also be
re-interpreted as upper bounds on the parameters describing violation of the
Equivalence Principle.Comment: 8 pages, 5 EPS figures, uses article.sty. Invited talk at C2CR 2005,
From Colliders to Cosmic Rays, Prague, Czech Republic, 7-13 September 200
MACRO constraints on violation of Lorentz invariance
The energy spectrum of neutrino-induced upward-going muons in MACRO has been
analysed in terms of relativity principles violating effects, keeping standard
mass-induced atmospheric neutrino oscillations as the dominant source of
transitions. The data disfavor these exotic
possibilities even at a sub-dominant level, and stringent 90% C.L. limits are
placed on the Lorentz invariance violation parameter at = 0 and at = 1. These limits can also be
re-interpreted as upper bounds on the parameters describing violation of the
Equivalence Principle.Comment: 3 pages, 2 figures. Presented at NOW 2006: Neutrino Oscillation
Workshop, Conca Specchiulla, Otranto, Italy, Sep 2006. To be published in
Nucl. Phys. B (Proc. Suppl.
Search for exotic contributions to atmospheric neutrino oscillations
The energy spectrum of neutrino-induced upward-going muons in MACRO was
analysed in terms of relativity principles violating effects, keeping standard
mass-induced atmospheric neutrino oscillations as the dominant effect. The data
disfavor these possibilities even at a sub-dominant level; stringent 90% C.L.
limits are placed on the Lorentz invariance violation parameter at = 0 and at = 1. The limits can be re-interpreted as
bounds on the Equivalence Principle violation parameters.Comment: Presented at the 29th I.C.R.C., Pune, India (2005
Gauge Theory Model of the Neutrino and New Physics Beyond the Standard Model
Majorana features of neutrinos and SO(3) gauge symmetry of three families
enable us to construct a gauge model of neutrino for understanding naturally
the observed smallness of neutrino masses and the nearly tri-bimaximal neutrino
mixing when combining together with the mechanism of approximate global U(1)
family symmetry. The vacuum structure of SO(3) symmetry breaking is found to
play an important role. The mixing angle and CP-violating phases
governed by the vacuum of spontaneous symmetry breaking are in general non-zero
and testable experimentally at the allowed sensitivity. The model predicts the
existence of vector-like SO(3) triplet charged leptons and vector-like SO(3)
triplet Majorana neutrinos as well as SO(3) tri-triplet Higgs bosons, some of
them can be light and explored at the colliders LHC and ILC.Comment: 15 pages, only typos in table 1 corrected in this replaced versio
Search for a Lorentz invariance violation contribution in atmospheric neutrino oscillations using MACRO data
Neutrino-induced upward-going muons in MACRO have been analysed in terms of
relativity principles violating effects, keeping standard mass-induced
atmospheric neutrino oscillations as the dominant source of nu_mu -> nu_tau
transitions. The data disfavor these exotic possibilities even at a
sub-dominant level, and stringent 90% C.L. limits are placed on the Lorentz
invariance violation parameter |Delta v| < 6 * 10^(-24) at sin2theta_v = 0 and
|Delta v| < 2.5--5 * 10^(-26) at sin2theta_v = +/-1. These limits can also be
re-interpreted as upper bounds on the parameters describing violation of the
Equivalence Principle.Comment: 8 pages, 2 figures, submitted to Physics Letters
Weakly coupled two slow- two fast systems, folded node and mixed mode oscillationsM
We study Mixed Mode Oscillations (MMOs) in systems of two weakly coupled
slow/fast oscillators. We focus on the existence and properties of a folded
singularity called FSN II that allows the emergence of MMOs in the presence of
a suitable global return mechanism. As FSN II corresponds to a transcritical
bifurcation for a desingularized reduced system, we prove that, under certain
non-degeneracy conditions, such a transcritical bifurcation exists. We then
apply this result to the case of two coupled systems of FitzHugh- Nagumo type.
This leads to a non trivial condition on the coupling that enables the
existence of MMOs
The Monge problem in Wiener Space
We address the Monge problem in the abstract Wiener space and we give an
existence result provided both marginal measures are absolutely continuous with
respect to the infinite dimensional Gaussian measure {\gamma}
Underground Muon Physics with the MACRO experiment
Underground muon events detected by the MACRO experiment at Gran Sasso have
been studied for different purposes. The studies include the vertical muon
intensity measurement, multiplicity distribution, lateral and angular muon
distribution and searches for substructures inside muon bundles. These analyses
have contributed to bring new insights in cosmic ray physics, in particular in
the framework of primary cosmic ray composition studies. Moreover, this
activity allows the testing and tuning of Monte Carlo simulations, in
particular for aspects associated with models of hadronic interactions and muon
propagation through the rock.Comment: 6 pages, 4 EPS figures included with epsfig, uses espcrc2.sty Talk
given at the Sixth Topical Seminar on Neutrino and Astroparticle Physics, San
Miniato, Italy, 17-21 May 199
Time correlations of high energy muons in an underground detector
We present the result of a search for correlations in the arrival times of
high energy muons collected from 1995 till 2000 with the streamer tube system
of the complete MACRO detector at the underground Gran Sasso Lab. Large samples
of single muons (8.6 million), double muons (0.46 million) and multiple muons
with multiplicities from 3 to 6 (0.08 million) were selected. These samples
were used to search for time correlations of cosmic ray particles coming from
the whole upper hemisphere or from selected space cones. The results of our
analyses confirm with high statistics a random arrival time distribution of
high energy cosmic rays.Comment: (12 pages, 7 figures, Accepted for publication in Astroparticle
Physics
- …