Search results for "Speed"
showing 10 items of 876 documents
High energy neutrino yields from astrophysical sources
2006
We calculate the yield and flavour content of high energy neutrinos produced in astrophysical sources with negligible magnetic fields varying their interaction depth. We take into account the scattering of secondaries on background photons as well as the direct production of neutrinos in decays of charm mesons. If multiple scattering of nucleons becomes important, the neutrino spectra from meson and muon decays are strongly modified with respect to transparent sources. Characteristic for neutrino sources containing photons as scattering targets is a strong energy-dependence of the ratio R0 of νμ and νe fluxes at the sources, ranging from R0=μ/e~0 below threshold to R0~4 close to the energy …
Neutrino oscillations and the seesaw origin of neutrino mass
2016
The historical discovery of neutrino oscillations using solar and atmospheric neutrinos, and subsequent accelerator and reactor studies, has brought neutrino physics to the precision era. We note that CP effects in oscillation phenomena could be difficult to extract in the presence of unitarity violation. As a result upcoming dedicated leptonic CP violation studies should take into account the non-unitarity of the lepton mixing matrix. Restricting non-unitarity will shed light on the seesaw scale, and thereby guide us towards the new physics responsible for neutrino mass generation.
Solar neutrino oscillation parameters and the broken R parity majoron
1989
Matter-enhanced neutrino-oscillation parameters can be probed in a variety of conventional experiments in supergravity models where the small neutrino mass arises from spontaneous R-parity violation. A combined analysis of astrophysical and laboratory limits tends to exclude regions of oscillation parameters where the high-energy neutrinos are adiabatically converted. This suggests the possibility of a large reduction in the pp and /sup 7/Be neutrino flux even for a mildly reduced /sup 8/B neutrino flux, thus stressing the importance of gallium experiments.
Precise Determination of the UnperturbedB8Neutrino Spectrum
2012
A measurement of the final state distribution of the B-8 beta decay, obtained by implanting a 8B beam in a double-sided silicon strip detector, is reported here. The present spectrum is consistent with a recent independent precise measurement performed by our collaboration at the IGISOL facility, Jyvaskyla [O. S. Kirsebom et al., Phys. Rev. C 83, 065802 ( 2011)]. It shows discrepancies with previously measured spectra, leading to differences in the derived neutrino spectrum. Thanks to a low detection threshold, the neutrino spectrum is for the first time directly extracted from the measured final state distribution, thus avoiding the uncertainties related to the extrapolation of R-matrix fi…
Screening of long-range leptonic forces by cosmic background neutrinos.
1995
The absence of dispersion effects of the SN~1987A neutrino pulse has been used to constrain novel long-range forces between neutrinos and galactic baryonic or non-baryonic matter. If these forces are mediated by vector bosons, screening effects by the cosmic neutrino background invalidate the SN~1987A limits and other related arguments.
Neutrino oscillation effects on the indirect signal of neutralino dark matter from the Earth core
1999
We investigate the effect induced by neutrino oscillation on the dark matter indirect detection signal which consists in a muon neutrino flux produced by neutralino annihilation in the Earth core. We consider the neutrino oscillation parameters relevant to the atmosferic neutrino deficit, both in the νμ → ντ and νμ → νs cases.
Effect of atmospheric flux uncertainties on the determination of the neutrino mass hierarchy
2016
The next generation of large-volume neutrino telescopes will include low-energy subarrays which will be able to measure neutrinos with energies of a few GeV. In this energy range the primary signal below the horizon is neutrinos created by cosmic ray interactions in the atmosphere. The measured event rate will depend on the neutrino mass hierarchy, allowing determination of this quantity to a significance level of about 3.5 sigma within a 5-year period, mostly limited by systematic uncertainties. We present here the impact of the uncertainties on the atmospheric neutrino flux normalization on the determination of the neutrino mass hierarchy. We suggest constraining the systematic uncertaint…
The Q-value of tritium β-decay and the neutrino mass
2006
Abstract The paper discusses the influence of β -endpoint energies and related atomic mass values on the determination of the neutrino mass in present and future β -decay experiments with particular emphasis on the case of tritium decay
Status of three-neutrino oscillation parameters
2012
Here we review the current status of global fits to neutrino oscillation data within the three-flavour framework. In our analysis we include the most recent data from solar and atmospheric neutrino experiments as well as the latest results from the long-baseline accelerator neutrino experiments and the recent measurements of reactor neutrino disappearance reported by Double Chooz, Daya Bay and RENO. We present updated determinations for the two neutrino mass splittings and the three mixing angles responsible for neutrino oscillations that, for the first time, have all been measured with 1 sigma accuracies ranging from 3 to 15%. A weak sensitivity for the CP violating phase is also reported …
Matter Effects in Neutrino Propagation
1989
After briefly reviewing the Mikheyev-Smirnov-Wolfenstein effect, I present a particle physics model where the required small neutrino mass arises from spontaneous R parity violation in supergravity theories. It is related to measurable processes associated with the existence of the Majoron and of supersymmetric (SUSY) particles. Astrophysical and laboratory limits tend to exclude regions of oscillation parameters where the high energy neutrinos are adiabatically converted. This suggests the possibility of a large reduction in the pp and 7 Be neutrino flux even for a mildly reduced 8 B neutrino flux, thus stressing the importance of the gallium experiments. Finally I consider other types of …