Search results for "oscillation"
showing 10 items of 1257 documents
Neutrino masses, leptogenesis, and dark matter in a hybrid seesaw model
2009
4 pages.-- ISI article identifier:000263816600020.-- ArXiv pre-print avaible at:http://arxiv.org/abs/0811.0953
Physics at new accelerators: Looking beyond the Standard Model
1993
Abstract Neutrino masses can have important implications in nuclear and particle physics, astrophysics and cosmology. Apart from the effects related to solar neutrinos, neutrino oscillations, dark matter, beta and double beta decays, massive neutrinos can also produce signals in the new accelerators. Here I focus on μ and τ number violating processes, very promising for muon and tau factories, as well as on the signatures associated with spontaneously broken R parity supersymmetry and neutral heavy leptons. These include the possibility of high rates for single chargino and neutralino production at LEP, LHC/SSC, as well as new signatures involving invisibly decaying Higgs bosons.
Neutrino magnetic moments and low-energy solar neutrino-electron scattering experiments
1998
The scattering of solar neutrinos on electrons is sensitive to the neutrino magnetic moments through an interference of electromagnetic and weak amplitudes in the cross section. We show that future low-energy solar neutrino experiments with good angular resolution can be sensitive to the resulting azimuthal asymmetries in event number and should provide useful information on non-standard neutrino properties such as magnetic moments. We compare asymmetries expected at HELLAZ (mainly pp neutrinos) with those at the Kamiokande and Super-Kamiokande experiments (Boron neutrinos), both for the case of Dirac and Majorana neutrinos and discuss the advantages of low energies. Potentially interesting…
Reconciling neutrino anomalies in a simple four-neutrino scheme with R-parity violation
2000
We propose a simple extension of the MSSM based on extra compact dimensions which includes an $SU(2) \otimes U(1)$ singlet superfield. The fermion present in this superfield is the sterile neutrino, which combines with one linear combination of $\nu_e-\nu_{\mu}-\nu_{\tau}$ to form a Dirac pair whose mass accounts for the LSND anomaly. Its small mass can be ascribed to a volume suppression factor associated with extra compact dimensions. On the other hand the sterile neutrino scalar partner can trigger the spontaneous violation of R-parity, thereby inducing the necessary mass splittings to fit also the solar and atmospheric neutrino data. Thus the model can explain all neutrino oscillation d…
Effects of sterile neutrinos on the ultrahigh-energy cosmic neutrino flux
2003
We investigate the effect of sterile neutrinos that are nearly degenerate with active ones on the flux of ultrahigh-energy cosmic ray neutrinos at earth. This offers a way to probe neutrino oscillations in the mass-squared range (10^{-16} eV^2 < ��m^2 < 10^{-11} eV^2) which maybe hard to detect by any other means. Taking into account the present experimental uncertainties of the active-active mixing angles and by allowing any values for the active-sterile mixing angles we find that the ratio of the electron and muon neutrino fluxes may change by -40 % to 70 % in comparison with the ratio in the absence of active-sterile mixing.
Status of the MSW Solutions to the Solar Neutrino Problem
2000
In this talk we present the results of an updated global analysis of two-flavor MSW solutions to the solar neutrino problem in terms of conversions of $\nu_e$ into active or sterile neutrinos including the the full data set corresponding to the 825-day Super-Kamiokande data sample as well as to Chlorine, GALLEX and SAGE experiments.
On the description of non-unitary neutrino mixing
2015
28 pages.- 8 figures.- typos corrected.- modified bounds on non-unitarity parameters.- new figs 3 and 4
Constraining neutrino oscillation parameters with current solar and atmospheric data
2002
We analyze the impact of recent solar, atmospheric and reactor data in the determination of the neutrino oscillation parameters, taking into account that both the solar nu_e and the atmospheric nu_mu may convert to a mixture of active and sterile neutrinos. We use the most recent global solar neutrino data, including the 1496-day Super-K neutrino data sample, and we investigate in detail the impact of the SNO neutral current, spectral and day/night data by performing also an analysis using only the charged current rate from SNO. The implications of the first 145.1 days of KamLAND data on the determination of the solar neutrino parameters are also discussed in detail. We confirm the clear pr…
Status of three-neutrino oscillations after the SNO-salt data
2003
We perform a global analysis of neutrino oscillation data in the framework of three neutrinos, including the recent improved measurement of the neutral current events at SNO. In addition to all current solar neutrino data we take into account the reactor neutrino data from KamLAND and CHOOZ, the atmospheric neutrino data from Super-Kamiokande and MACRO, as well as the first spectral data from the K2K long baseline accelerator experiment. The up-to-date best fit values and allowed ranges of the three-flavour oscillation parameters are determined from these data. Furthermore, we discuss in detail the status of the small parameters alpha = Delta_m^2_Sol / Delta_m^2_Atm and sin^2(theta_13), whi…
Supernova Bounds on Majoron-emitting decays of light neutrinos
2000
Neutrino masses arising from the spontaneous violation of ungauged lepton-number are accompanied by a physical Goldstone boson, generically called Majoron. In the high-density supernova medium the effects of Majoron-emitting neutrino decays are important even if they are suppressed in vacuo by small neutrino masses and/or small off-diagonal couplings. We reconsider the influence of these decays on the neutrino signal of supernovae in the light of recent Super-Kamiokande data on solar and atmospheric neutrinos. We find that majoron-neutrino coupling constants in the range $3\times 10^{-7}\lsim g\lsim 2\times 10^{-5}$ or $g \gsim 3 \times 10^{-4}$ are excluded by the observation of SN1987A. T…