On Nov 24, 4:25 pm, Joe Snodgrass wrote:
Am I correct in my understanding that, although it was discovered in
1998 that the neutrino does indeed have mass, people still don't know
what that mass is? TIA.

Yes, that is correct. There are both lower and upper experimental bounds on
delta(m^2), the difference in the masses-squared of the different neutrino mass
eigenstates, but these are dependent on the values of the various mixing angles,
some of which are highly uncertain.

From tritium decay an upper bound of a few eV/c^2 on nu_e_bar has been known
for a long time. The neutrino oscillation experiments put limits on delta(m^2)
in the range of a few eV^2/c^4 for some pairs, and ~1,000 times smaller for others.

These limits are very much smaller than the mass of the lowest-mass particle for
which the mass is known, the electron at 510,999 eV/c^2.

Look up "neutrino oscillations" for more information.


Tom Roberts