Nonvacuum initial states for cosmological perturbations of quantum-mechanical origin

In the context of inflation, non-vacuum initial states for cosmologicalperturbations that possess a built in scale are studied. It is demonstratedthat this assumption leads to a falsifiable class of models. The question ofwhether they lead to conflicts with the available observations is addressed.For this purpose, the power spectrum of the Bardeen potential operator iscalculated and compared with the CMBR anisotropies measurements and theredshift surveys of galaxies and clusters of galaxies. Generic predictions ofthe model are: a high first acoustic peak, the presence of a bump in the matterpower spectrum and non-Gaussian statistics. The details are controlled by thenumber of quanta in the non-vacuum initial state. Comparisons with observationsshow that there exists a window for the free parameters such that goodagreement between the data and the theoretical predictions is possible.However, in the case where the initial state is a state with a fixed number ofquanta, it is shown that this number cannot be greater than a few. On the otherhand, if the initial state is a quantum superposition, then a larger class ofinitial states could account for the observations, even though the state cannotbe too different from the vacuum. Planned missions such as the MAP and Plancksatellites and the Sloan Survey, will demonstrate whether the new class ofmodels proposed here represents a viable alternative to the standard theory.Comment: revtex, 15 pages, 10 figures. Submitted to Phys.Rev.