  The inflationary paradigm is an important cornerstone of the concordance
cosmological model. However, standard inflation cannot fully address the
transition from an early homogeneous and isotropic stage, to another one
lacking such symmetries corresponding to our present universe. In previous
works, a self-induced collapse of the wave function has been suggested as the
missing ingredient of inflation. Most of the analysis regarding the collapse
hypothesis has been solely focused on the characteristics of the spectrum
associated to scalar perturbations, and within a semiclassical gravity
framework. In this Letter, working in terms of a joint metric-matter
quantization for inflation, we calculate, for the first time, the tensor power
spectrum and the tensor-to-scalar ratio corresponding to the amplitude of
primordial gravitational waves resulting from considering a generic
self-induced collapse.
