...MASS

Invited talk, presented at Pascos/Hopkins-95, Baltimore, 3/95.

...nucleosynthesis

In fact, a recent analysis of the abundances of light elements yields [2] 5#5 light neutrino species, suggesting (a) non-standard neutrino physics, such as a massive, short-lived 6#6, (b) an underestimate of the observational uncertainties in the determination of the 7#7He abundance, or (c) large theoretical uncertainties in the estimate [3] of the D abundance from the solar system observations of 8#8He.

...(L)-handed

The subscripts L and R really refer to the left and right chiral projections. In the limit of zero mass these correspond to left and right helicity states.

...neutrinos

A left (right)-handed particle is associated under CPT with a right (left)-handed antiparticle. The two together constitute a Weyl spinor.

...sterile

Sterile neutrinos are often referred to as ``right-handed'' neutrinos, but that terminology is confusing and inappropriate when Majorana masses are present.

...eigenstates

In the Dirac limit, 50#50, the two Majorana mass eigenstates, 51#51 CPT-partner, are degenerate and can be combined to form a Dirac neutrino.

...masses

This is an approximation valid if all of the 89#89 MeV.

...components

The uncertainties associated with 133#133 are negligible.

...oscillations

Oscillations into sterile neutrinos are strongly disfavored by nucleosynthesis constraints [16].

...situation

One interesting possibility involves three-family oscillations, with the 208#208 and 209#209 much lighter than the 210#210 [63].

Mon Nov 27 19:37:58 EST 1995