Recall that j 2 j 2 j j j 2 j a 1 this

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Unformatted text preview: τ=⎜ ⎟ 2 ⎝0 −1⎠ 3 1 1 3 j µ = χ L γ µ 1 τ 3 χ L = ν L γ µν L − eL γ µ eL 2 2 2 Here we have “predicted” the existence of a weak neutral current process. However, this sBll only couples LH parBcles to LH parBcles, while we know that the Z0 has RH couplings as well (or the vertex factor would be just V ­A like the charged weak interacBon). Consider the so ­called weak ­hypercharge current (which is a mixture of the two neutral 1 3 em currents j µ and j µ ): [ here the weak hypercharge Y is defined by Q = I 3 + 2 Y ] ⎛1 ⎞ 1 Y em 3 j µ = 2 j µ − 2 j µ = 2(−eR γ µ eR − eL γ µ eL ) − 2⎜ ν L γ µν L − eL γ µ eL ⎟ ⎝2 ⎠ 2 = −2 eR γ µ eR − eL γ µ eL − ν L γ µν L 14 Y j µ = −2 e R γ µ e R − e L γ µ e L − ν L γ µ ν L is invariant under a weak ­isospin transformaBon eR →...
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This document was uploaded on 02/11/2014.

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