- #1

spaghetti3451

- 1,344

- 33

Expanding the field ##\phi## about the point ##\phi=\phi_{-}## (##\phi = \phi_{-}+ \varphi##) and keeping terms up to dimension four, we find

##U(\varphi)=\frac{m^{2}}{2}\varphi^{2}-\eta\varphi^{3}+\frac{\lambda}{8}\varphi^{4}##,

where ##m^{2}=\frac{\lambda}{2}(3\phi_{-}^{2}-a^{2})## and ##\eta = \frac{\lambda}{2}\lvert\phi_{-}\lvert##.

How do you derive this potential ##U(\varphi)## in explicit steps? Can you provide just the first two lines? I'll work out the rest for myself.