9 research outputs found
On the massless "just-so" solution to the solar neutrino problem
We study the effect of the non-resonant, vacuum oscillation-like neutrino
flavor conversion induced by non-standard flavor changing and non-universal
flavor diagonal neutrino interactions with electrons in the sun. We have found
an acceptable fit for the combined analysis for the solar experiments total
rates, the Super-Kamiokande (SK) energy spectrum and zenith angle dependence.
Phenomenological constraints on non-standard flavor changing and non-universal
flavor diagonal neutrino interactions are considered.Comment: 4 pages, Latex, uses eps
Search for Heavy Leptons at Hadron Colliders
Four models are considered which contain heavy leptons beyond the three
families of the standard model. Two are fourth-generation extensions of the
standard model in which the right-handed heavy leptons are either isosinglets
or in an isodoublet; the other two are motivated by the aspon model of CP
violation. In all these models, the heavy neutrino can either be heavier than,
or comparable in mass to, the charged lepton leading to the possibility that
the charged lepton is very long-lived. Production cross section and signatures
for the heavy leptons are computed for the SSC and LHC.Comment: 17 pages(8 figures are not included),TRI-PP-92-9
In Quest of Neutrino Masses at (eV) Scale
Neutrino oscillation and tritium beta decay experiments taken simultaneously
into account are able to access the so far imperceptible absolute neutrino
masses at the electronvolt level. The neutrino mass spectrum derived in this
way is independent of the nature of neutrinos (Dirac or Majorana). Furthermore,
the lack of neutrinoless double beta decay gives additional constraints on the
Majorana neutrino mass spectrum. A case of three neutrinos is examined.
Influence of different solutions to the solar neutrino deficit problem on the
results is discussed. Apart from the present situation, four qualitatively
distinct experimental situations which are possible in the future are
investigated: when the two decay experiments give only upper bounds on
effective neutrino masses, when either one of them gives a positive result, and
when both give positive results. The discussion is carried out by taking into
account the present experimental errors of relevant neutrino parameters as well
as their much more precise expected estimations (e.g. by factories). It
is shown in which cases the upgraded decay experiments simultaneously with
neutrino oscillation data may be able to fix the absolute scale of the neutrino
mass spectrum, answer the question of the neutrino nature and put some light on
CP phases in the lepton sector.Comment: 30 pages, 6 figs, to appear in PR
CP violation effect in long-baseline neutrino oscillation in the four-neutrino model
We investigate CP-violation effect in the long-baseline neutrino oscillation
in the four-neutrino model with mass scheme of the two nearly degenerate pairs
separated with the order of 1 eV, by using the data from the solar neutrino
deficit, the atmospheric neutrino anomaly and the LSND experiments along with
the other accelerator and reactor experiments. By use of the most general
parametrization of the mixing matrix with six angles and six phases, we show
that the genuine CP-violation effect could attain as large as 0.3 for and that the matter effect is negligibly
small such as at most 0.01 for for , which is the mass-squared difference relevant
to the long-baseline oscillation.Comment: 21 pages in LaTeX, 9 ps figures. Some changes in the Introduction and
Reference
Status of global fits to neutrino oscillations
We review the present status of global analyses of neutrino oscillations,
taking into account the most recent neutrino data including the latest KamLAND
and K2K updates presented at Neutrino2004, as well as state-of-the-art solar
and atmospheric neutrino flux calculations. We give the two-neutrino solar +
KamLAND results, as well as two-neutrino atmospheric + K2K oscillation regions,
discussing in each case the robustness of the oscillation interpretation
against departures from the Standard Solar Model and the possible existence of
non-standard neutrino physics. Furthermore, we give the best fit values and
allowed ranges of the three-flavour oscillation parameters from the current
worlds' global neutrino data sample and discuss in detail the status of the
small parameters \alpha \equiv \Dms/\Dma as well as ,
which characterize the strength of CP violating effects in neutrino
oscillations. We also update the degree of rejection of four-neutrino
interpretations of the LSND anomaly in view of the most recent developments.Comment: v6: In the last Appendix we provide updated neutrino oscillation
results which take into account the relevant oscillation data released by the
MINOS and KamLAND collaboration
Constraints on Neutrino Oscillations Using 1258 Days of Super-Kamiokande Solar Neutrino Data
We report the result of a search for neutrino oscillations using precise
measurements of the recoil electron energy spectrum and zenith angle variations
of the solar neutrino flux from 1258 days of neutrino-electron scattering data
in Super-Kamiokande. The absence of significant zenith angle variation and
spectrum distortion places strong constraints on neutrino mixing and mass
difference in a flux-independent way. Using the Super-Kamiokande flux
measurement in addition, two allowed regions at large mixing are found.Comment: 6 pages, 4 figures, submitted to PR