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R. N. Mohapatra
Ray Davis and colleagues observed the solar neutrinos in 1969 and found a
deficit over what was theoretically predicted by John Bahcall, of Princeton.
That observation could be interpreted as oscillation of neutrinos coming
from the sun (see later for more details), providing support for the ideas of
Pontecorvo, Maki, Nakagawa, and Sakata.
9.5 Charged Weak Force Comes Accompanied
by Neutral Weak Force
As we mentioned, weak forces were thought in the 1960s to only change
a neutron to a proton. They were called charged current weak force, since
they change the electric charge. Then in the 1970s, a momentous discovery
was made by scientists at CERN who found a new kind of weak force in
neutrino scattering off neutrons and protons, where the charge of the nucleus
did not change. They were called neutral current weak interactions. It was
discovered in 1973 [90] and was the first evidence for a complete theory
of weak interactions, suggested by S. L. Glashow, Abdus Salam, and Steven
Weinberg. We will discuss this theory further in the next chapter.