We show that the phenomenon of spontaneous scalarization predicted in neutron
stars within the framework of scalar-tensor tensor theories of gravity, also
takes place in boson stars without including a self-interaction term for the
boson field (other than the mass term), contrary to what was claimed before.
The analysis is performed in the physical (Jordan) frame and is based on a 3+1
decomposition of spacetime assuming spherical symmetry.Comment: Minor changes to match the final version to appear in PR