I have two questions, both relating to the SSB of Electroweak Lagrangian.
My notes say that after breaking and expanding around the VEV, the masses of $W$ and $Z$ are identified by comparing to the lagrangian
$$ L = m_{w}W^+_\mu W^{-\mu} + {\frac{1}{2}}mZZ. $$
My first question is why the factor of half for the case of the $Z$ bosons mass?
My other question is how the transformation to the unitary gauge
$$ \phi = \frac{1}{\sqrt{2}}(\frac{0}{v + H(x)}) $$ explicitly works, as in what does the transformation from the complex Higgs Doublet actually look like. Most texts I can find just state it, but I'm not sure how the process works.