Next: Acknowledgement
Up: Solar Neutrinos (Erice 1994)
Previous: Implications
-
There is no compelling laboratory evidence for neutrino mass.
- However, neutrino masses are non-zero in most extensions of the
standard model, typically ,
where v = 246 GeV is the weak scale. Thus, probing small neutrino masses
indirectly probes the large mass scales of new physics.
- A deficit of solar neutrinos is observed in four experiments. The
less serious solar neutrino problem is the deficit of neutrinos, which
could well be accounted for by small changes in the astrophysics. Much
more serious is that any two of the three classes of experiments can be
combined to indicate that the dominant suppression is in the middle of the
spectrum, in particular of the neutrinos and the lower energy part of
the neutrinos. This is incompatible with any known astrophysical or
nuclear physics explanation, suggesting either non-standard neutrino
properties or that some of the experiments are wrong. On the other hand,
the MSW oscillations give a perfect description of the data. Detailed MSW
analyses, including the Earth effect, the day/night asymmetry data,
theoretical uncertainties, and their correlations indicate that there are
two parameter solutions, both in the general range expected from grand
unification, although the details are model dependent. One can also
simultaneously determine the MSW and solar parameters. One finds a core
temperature , in remarkable agreement with the
standard model expectation . Alternately, one can constrain
the boron neutrino flux, yielding ,
consistent with but slightly higher than the SSM expectation. In the
future it should be possible with new experiments to determine the initial
pp, , and fluxes, with or without MSW being present, in a model
independent way.
- There are also anomalies in the atmospheric
ratio produced by cosmic ray interactions in the atmosphere. This could
also be a sign of neutrino oscillations.
- The combination of COBE data and the large and small scale
distribution of galaxies is hard to account for by pure cold dark matter.
One possibility is a component of hot dark matter, such as a
neutrino in the 10 eV range.
- The possibilities are very exciting. It is quite possible that
neutrino mass will be the first clear break with the standard electroweak
model. However, much experimental and theoretical work remains.
Next: Acknowledgement
Up: Solar Neutrinos (Erice 1994)
Previous: Implications
Mon Nov 27 19:39:39 EST 1995