Standard Model and Beyond · Problem 7.4

The Standard Electroweak Theory

Physics — Particle Physics · qed-corrections-mu-beta-decay

Problem

Discuss the difference between the QED corrections to

\mu

and

\beta

decay in the Fermi theory. Hint: Use an effective interaction

-\mathcal{L}_\beta = \frac{G_F}{\sqrt{2}} \bar{p}\gamma_\mu \left(1 - \gamma^5\right) n \; \bar{e}\gamma^\mu \left(1 - \gamma^5\right) \nu_e

for

\beta

decay, and write the four-fermi interactions in each case in charge retention form.