We know that electromagnetic current can be written as [tex] j^{\mu}_{em} = \frac{1}{6} \bar{Q} \gamma^\mu Q + \bar{Q} \gamma^\mu \frac{\tau^3}{2} Q [/tex] where [itex] Q = \begin{pmatrix} u \\ d \end{pmatrix} [/itex]. We say this induces a transition with [itex] |\Delta I|=1, \Delta I_z =0 [/itex]. What should we understand under that last statement? How do we see that?(adsbygoogle = window.adsbygoogle || []).push({});

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# Isospin current

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