19,309 research outputs found
Searches for new particles at LEP: a summary report
We review the progress made at LEP in the quest for new particles.Comment: 10 pages, latex, 1 figure, summary talk given at `13th Convegno sulla
Fisica al LEP (LEPTRE 2001)', Rome, Italy, 18-20 April 200
The flat X-ray spectrum of the LINER NGC1052
We report on ROSAT and ASCA observations of the LINER NGC1052, which is the
first one where broad optical lines in polarized light have been observed. The
2-10 keV spectrum is very flat, with an observed photon index (Gamma) ~0.1. A
model where a nuclear source is - partly or totally - obscured by a screen of
matter with column density ~10^23 atom/cm/cm is the most convincing explanation
for the observed flatness. This agrees with the hypothesis that the LINERs are
a population of low-luminosity AGN, to which the Seyfert unification scenario
applies. The intrinsic spectral index is still rather flat (1.0-1.4), as
observed in a few type-2 Seyferts so far or predicted if the accretion occurs
in an advection-dominated flow.Comment: 5 pages, Latex, 2 Postscript figures, accepted for publication in
MNRA
Neutrino oscillations and Lorentz Invariance Violation in a Finslerian Geometrical model
Neutrino oscillations are one of the first evidences of physics beyond the
Standard Model (SM). Since Lorentz Invariance is a fundamental symmetry of the
SM, recently also neutrino physics has been explored to verify the eventual
modification of this symmetry and its potential magnitude. In this work we
study the consequences of the introduction of Lorentz Invariance Violation
(LIV) in the high energy neutrinos propagation and evaluate the impact of this
eventual violation on the oscillation predictions. An effective theory
explaining these physical effects is introduced via Modified Dispersion
Relations. This approach, originally introduced by Coleman and Glashow,
corresponds in our model to a modification of the special relativity geometry.
Moreover, the generalization of this perspective leads to the introduction of a
maximum attainable velocity which is specific of the particle. This can be
formalized in Finsler geometry, a more general theory of space-time. In the
present paper the impact of this kind of LIV on neutrino phenomenology is
studied, in particular by analyzing the corrections introduced in neutrino
oscillation probabilities for different values of neutrino energies and
baselines of experimental interest. The possibility of further improving the
present constraints on CPT-even LIV coefficients by means of our analysis is
also discussed.Comment: Accepted for publication with minor revisions, will appear on
European Physics Journal
Full QCD on APE100 Machines
We present the first tests and results from a study of QCD with two flavours
of dynamical Wilson fermions using the Hybrid Monte Carlo Algorithm (HMCA) on
APE100 machines.Comment: 23 pages, LaTeX, 13 PS figures not include
Study of the performance of the NA62 Small-Angle Calorimeter at the DANE Linac
The measurement of with 10% precision by the
NA62 experiment requires extreme background suppression. The Small Angle
Calorimeter aims to provide an efficient veto for photons flying at angles down
to zero with respect to the kaon flight direction. The initial prototype was
upgraded and tested at the Beam Test Facility of the DANE Linac at
Frascati. The energy resolution and the efficiency were measured and are
presented.Comment: 5 pages, 7 figure
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