Kinematic constraints to the key inflationary observables

The observables T/S and n-1 are key to testing and understanding inflation. (T, S, and n-1 respectively quantify the gravity-wave and density-perturbation contributions to CMB anisotropy and the deviation of the density perturbations from the scale-invariant form.) Absent a standard model, there is no definite prediction for, or relation between, T/S and n-1. By reformulating the equations for slow-roll inflation, we show that in the T/S-(n-1) plane there are excluded regions, regions in which the density perturbations are not well approximated by a power law, and regions in which models with a "featureless" potential must lie.