I'm reading about the Higgs mechanism considering the Lagrangian: $$ \mathcal{L}=-\frac{1}{4}F^{\mu\nu}F_{\mu\nu} + \left(D_\mu\phi\right)\left(D^\mu\phi\right)^\dagger-\mu^2\left(\phi\phi\right)^\dagger-\lambda\left(\phi\phi^\dagger\right)^2 $$
Breaking the symmetry one arrives to the existence of Goldsone bosons: $$ \mathcal{L} = \frac{1}{2}\left(\partial^\mu\eta\right)\left(\partial_\mu\eta\right)-\lambda v^2\eta^2+\frac{1}{2}\left(\partial_\mu\xi\right)\left(\partial^\mu\xi\right)-\frac{1}{4}F^{\mu\nu}F_{\mu\nu}+\frac{1}{2}q^2v^2A_\mu A^\mu+qvA_\mu\partial^\mu\xi-V_{int}\left(\eta,\xi,A^\mu\right) $$ where $\phi=\frac{1}{\sqrt{2}}(v+\eta(x)+i\xi(x))$
Are these bosons measurable?
