Weak isospin
| Flavour in particle physics | 
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| Flavour quantum numbers | 
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| Related quantum numbers | 
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| Combinations | 
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| Flavour mixing | 
In particle physics, weak isospin is a quantum number relating to the electrically charged part of the weak interaction: Particles with half-integer weak isospin can interact with the  W±
  bosons; particles with zero weak isospin do not.
Weak isospin is a construct parallel to the idea of isospin under the strong interaction. Weak isospin is usually given the symbol T or I, with the third component written as T3 or I3 .  T3 is more important than T; typically "weak isospin" is used as short form of the proper term "3rd component of weak isospin". It can be understood as the eigenvalue of a charge operator.