Abstract. The success of the inflationary paradigm rests on its ability to explain the observed classicality of primordial quantum fluctuations despite their quantum origin which calls for a mechanism for quantum-to-classical transition of these initial fluctuations. As literature suggests a number of plausible mechanisms which try to address this issue, it is of importance to seek concrete observational signatures of the various approaches in order to have a better understanding of the early universe dynamics. Squeezing of primordial cosmological inhomogeneities along with the mechanism of decoherence accounts for many aspects of this quantum to classical transition, although it remains a matter of debate as to whether this is sufficient to explain the issue of realization of a single outcome from a quantum ensemble given that the universe is a closed system. Apart from decoherence there have been several attempts to resolve this issue. Among these several approaches, it is the spontaneous collapse dynamics of Quantum Mechanics, a stochastic nonlinear modification of the non-relativistic Schrodinger equation, which is most viable for leaving discrete observational signatures as collapse mechanism inherently changes the generic quantum dynamics.

In this talk, I shall revisit one such recently proposed working model of classicalization by spontaneous collapse, known as Continuous Spontaneous Localization (CSL), to look for possible modifications to scalar and tensor power spectra for canonical single field slow-roll inflation and their implications. I shall show that it can potentially change the consistency relation of single-field models and a precise measurement of tensor spectral tilt nt and its running could serve as a test of such dynamics in the early universe.

In the later part of my talk, I shall discuss about the application of the collapse dynamics to the more generalized non-canonical k-inflationary scenario and try to quantify the effects of collapse on inflationary dynamics, hence compare the results from both the approaches. We observe in this study that the observables from the scalar sector, i.e. scalar tilt ns, running of scalar tilt αs and running of running of scalar tilt βs, can not potentially distinguish a collapse modified inflationary dynamics in the realm of canonical scalar field and k−inflationary scenarios. The only distinguishable imprint of collapse mechanism lies in the observables of tensor sector in the form of modified consistency relation and a blue-tilted tensor spectrum only when the collapse parameter δ is non-zero and positive.

Lastly, I shall talk about plausible other approaches by which one can try to investigate the quantumness of primordial cosmological fluctuations and look for the effect of CSL on these approaches.
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