Solution
= Solution
Use <unitary gauge> and write $\phi=v+h/\sqrt2$. The quadratic Lagrangian contains
$$
\frac12(\partial h)^2-\lambda v^2h^2+e^2v^2A_\mu A^\mu.
$$
Thus the radial Higgs excitation is a spin-zero particle with $m_h^2=2\lambda v^2$, while the gauge boson is a massive spin-one particle with $m_A^2=2e^2v^2$. The phase of $\phi$ is the <Goldstone boson> eaten by the <Higgs mechanism> to supply the longitudinal polarization of $A_\mu$.