Which of the following symbols does
not represent a real neutrino?
So here we have a list of four
answer options, and each one consists of a lowercase Greek letter 𝜈. This is a character that looks kind
of like a curly letter V, and each one is followed by a different letter written in
subscript. This first one is the Greek letter
𝜇. This one of course we know as the
letter 𝑒. This character looks like an E, but
it’s actually a lowercase Greek letter 𝜖. And finally, this is the Greek
letter 𝜏. What we need to do is determine
which of these does not represent a real neutrino.
We can recall that all neutrinos
are represented by the Greek letter 𝜈. We can also recall that there are
three varieties of neutrino: the electron neutrino, the mu neutrino, and the tau
neutrino. Each of these also has its own
antiparticle. These are the electron
antineutrino, the mu antineutrino, and the tau antineutrino. As we can see, these particles are
named after the negatively charged leptons: the electron, muon, and tauon. And these negatively charged
leptons are represented by the symbols 𝑒 minus, 𝜇 minus, and 𝜏 minus. Because the neutrinos are named
after these three leptons, they also make use of the symbols 𝑒, 𝜇, and 𝜏. So we represent an electron
neutrino with a letter 𝜈 to signify that it’s a neutrino, followed by a subscript
𝑒 to signify that it is an electron neutrino.
Similarly, the muon neutrino is
represented by a 𝜈 followed by a subscript 𝜇. And the tau neutrino is represented
by a 𝜈 followed by a subscript 𝜏. The antineutrinos follow the same
pattern, but with a bar over the top to signify that they are antineutrinos. So looking again at our answer
options, we can see that option (A) corresponds to a mu neutrino, option (B)
corresponds to an electron neutrino, and option (D) corresponds to a tau
neutrino. So we can see that it’s option (C),
𝜈 sub 𝜖, which does not represent a real neutrino.