Constraining inflation (https://cerncourier.com/a/exploring-the-cmb-like-never-before/)

The Honourable Schoolboy 

Constraining inflation Current (light blue and purple) and anticipated (red) CMB-S4 constraints on the scalar-to-tensor ratio r compared with the predictions of various inflationary models that naturally explain the observed value of the spectral “tilt” of the power spectrum, ns = 0.965. The popular Starobinsky and Higgs inflation models are shown as grey and black circles. The lines show models with different masses of the inflaton in units of the Planck mass MP and N* is the number of e-folds. The corresponding inflation potentials φP all either polynomially or exponentially approach a plateau. Source: arXiv:1907.04473

Nb. If  CMB-S4 brings this to ~10^-4 ie 0,0001 or so wrt 'r', well seems inflation getting fragile and fragile as time goes by. So, play it Sam!