Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Feynman rules for electroweak multiplets

  1. Oct 11, 2011 #1
    Can someone refer me to Feynman rules for electroweak interactions in the general case of SU(2) multiplets of weak isospin n and weak hypercharge Y interacting with EW gauge bosons?

    I can only find the standard rules for SU(2) doublet electron - neutrino.

  2. jcsd
  3. Oct 11, 2011 #2


    User Avatar
    Science Advisor

    The interaction term in the standard model Lagrangian is

    Lγμ(i∂μ - g/2 τ·Wμ - g'/2 Y Bμ)L + Rγμ(i∂μ - g'/2 Y Bμ)R

    where L and R are left- and right-handed fermions and τ are the three Pauli matrices. So all you would have to do for an isospin n fermion is to replace τ by the three SU(2) matrices for isospin n, which are given by

    τ±|n m> = √(n∓m)(n±m+1) |n m±1>
    τ3|n m> = m |n m>
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook