Resurrecting Vanilla Power Law Inflation with the aid of Continuous Spontaneous Localization in the ACT era

Abstract: The Vanilla Power Law Inflation is plagued with two severe drawbacks, the one being the issue of graceful exit, and the other being its compatibility with the existing data. There's yet another daunting problem generic to any inflationary model, and not particular to the Power Law Inflation, is the issue of classicalization of the primordial quantum perturbation. This issue is often treated as an isolated problem primarily because decoherence is often invoked to tackle such problems and decoherence, in principle, doesn't leaves any observational imprints. However, that's not the case if one invokes the collapse models of quantum mechanics to resolve such a problem, because the collapse models do modify the Schr\"{o}dinger evolution of the quantum system and the modified dynamics is bound to leave imprints. We show that collapsed modified Power Law Inflation can indeed circumvent the issue with observations and can be made compatible with all the current data coming from {\it Planck}, {\it ACT}, DESI and BAO while resolving the classicalization issue associated with the quantum primordial fluctuations. Such an inflationary model also produces a more red-tilted tensor spectrum and no running for both the scalar and tensor spectral indices, which can be a litmus test for this model.