Double Monodromy Inflation: A Gravity Waves Factory for CMB-S4, LiteBIRD
  and LISA
  We consider a short rollercoaster cosmology based on two stages of monodromy
inflation separated by a stage of matter domination, generated after the early
inflaton falls out of slow roll. If the first stage is controlled by a flat
potential, $V \sim \phi^p$ with $p < 1$ and lasts ${\cal N} \sim 30 - 40$
efolds, the scalar and tensor perturbations at the largest scales will fit the
CMB perfectly, and produce relic gravity waves with $0.02 \lesssim r \lesssim
0.06$, which can be tested by LiteBIRD and CMB-S4 experiments. If in addition
the first inflaton is strongly coupled to a hidden sector $U(1)$, there will be
an enhanced production of vector fluctuations near the end of the first stage
of inflation. These modes convert rapidly to tensors during the short epoch of
matter domination, and then get pushed to superhorizon scales by the second
stage of inflation, lasting another $20-30$ efolds. This band of gravity waves
is chiral, arrives today with wavelengths in the range of $10^8$ km, and with
amplitudes greatly enhanced compared to the long wavelength CMB modes by vector
sources. It is therefore accessible to LISA. Thus our model presents a rare
early universe theory predicting several simultaneous signals testable by a
broad range of gravity wave searches in the very near future.
