Scalar interactions after complete SU2 breaking
= Scalar interactions after complete SU2 breaking
{title2=$m_h^2=\lambda v^2$}
In <unitary gauge>, $\phi=(0,(v+h)/\sqrt2)^T$ gives $\frac{g^2}{8}(v+h)^2A_\mu^aA^{a\mu}$. With potential $\frac{\lambda}{2}(\phi^\dagger\phi-v^2/2)^2$, the physical scalar has $m_h^2=\lambda v^2$ and interactions $-\lambda vh^3/2-\lambda h^4/8$. This normalization matters when extracting both masses and identical-leg <Feynman vertices>.