# I How is weak isospin/hypercharge calculated?

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1. Feb 20, 2017

### Harry235435

I am familiar with the following equation which relates weak isospin (T3) and weak hypercharge (YW):
YW = 2(Q-T3)
(Where Q is electric charge)
However, while this can be used to calculate YW from T3 and vice versa, how do you calculate each of these properties individually, without using the other?

2. Feb 21, 2017

### Jonathan Scott

Weak isospin is assigned to the usual (left-handed chirality) leptons and quarks in such a way as to distinguish the two different charge states in each generation, in the same way that normal isospin distinguishes the up and down quarks. I think that for those particles T3 = Q + L/2 - B/2 where Q is the charge, L is the lepton number and B is the baryon number.

There's a table of weak isospin and weak hypercharge for those particles in the Wikipedia article on weak hypercharge.