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Question

What is a neutrino?
Asked by: Derek Willingham

Answer

A neutrino is one of the elementary particles, a lepton with zero charge, spin � and extremely small mass. Neutrinos come in three varieties, each associated with an electron-like lepton: the electron neutrino, the muon neutrino and the tau neutrino.

The need for neutrinos (sticky electron neutrinos) was first pointed out by Wolfgang Pauli, in 1930, to explain the missing energy in beta decay. Later in 1956 neutrino were proved to exist, and in 1980�s cosmologists started to explore the possibility that neutrinos may make up some of the dark matter in the universe.
Answered by: Dan Summons, Physics Undergrad Student, UOS, Souhampton


A) Elementary Fermions
   1) leptons
      a) electrons
      b) muons
      c) tau
      d) electron neutrinos (written ve)
      e) muon neutrinos (vm)
      f) tau neutrinos (vt)
   2) quarks in red, green, or blue
      a) up and down
      b) charm and strange
      c) top and bottom

B) Composite fermions - odd # of elementary particles
   1) Baryons- composed of three quarks
      a) protons
      b) neutrons
      c) some nuclei
      d) lambda
      e) sigma

C) Bosons - Force mediators
   1) gravitons
   2) W+, W-, Z
   3) photons
   4) gluons color (8 valid combination of quarks)

D) Bosons (Hadrons: made of quarks) Mesons (36 valid combinations of 2 quarks)
   1) pion
   2) kaon
   3) D
   4) mu

Answered by: Eric , Undergrad Student


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