PHYS08200605006 D.K. Hazra - Homi Bhabha National Institute
PHYS08200605006 D.K. Hazra - Homi Bhabha National Institute
PHYS08200605006 D.K. Hazra - Homi Bhabha National Institute
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CONTENTS<br />
3.1.2 Priors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45<br />
3.1.3 Comparison with the recent CMB observations . . . . . . . . . . . . . 46<br />
3.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48<br />
3.2.1 The best fit background and inflationary parameters . . . . . . . . . 48<br />
3.2.2 The spectra and the improvement in the fit . . . . . . . . . . . . . . . 49<br />
3.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54<br />
4 Bi-spectra associated with local and non-local features 57<br />
4.1 Models of interest and power spectra . . . . . . . . . . . . . . . . . . . . . . . 59<br />
4.1.1 Inflationary potentials with a step . . . . . . . . . . . . . . . . . . . . 59<br />
4.1.2 Oscillations in the inflaton potential . . . . . . . . . . . . . . . . . . . 60<br />
4.1.3 Punctuated inflaton and the Starobinsky model . . . . . . . . . . . . 60<br />
4.1.4 The power spectra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61<br />
4.2 The scalar bi-spectrum in the Maldacena formalism . . . . . . . . . . . . . . 63<br />
4.3 The numerical computation of the scalar bi-spectrum . . . . . . . . . . . . . 65<br />
4.3.1 The contributions to the bi-spectrum on super-Hubble scales . . . . . 65<br />
4.3.2 An estimate of the super-Hubble contribution to the<br />
non-Gaussianity parameter . . . . . . . . . . . . . . . . . . . . . . . . 70<br />
4.3.3 Details of the numerical methods . . . . . . . . . . . . . . . . . . . . . 73<br />
4.3.4 Comparison with the analytical results in the cases of power law<br />
inflation and the Starobinsky model . . . . . . . . . . . . . . . . . . . 76<br />
4.4 Results in the equilateral limit . . . . . . . . . . . . . . . . . . . . . . . . . . . 81<br />
4.5 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84<br />
5 The scalar bi-spectrum during preheating 85<br />
5.1 Behavior of background and perturbations during preheating . . . . . . . . 87<br />
5.1.1 Background evolution about a quadratic minimum . . . . . . . . . . 87<br />
5.1.2 Evolution of the perturbations . . . . . . . . . . . . . . . . . . . . . . 92<br />
5.2 The contributions to the bi-spectrum during preheating . . . . . . . . . . . . 98<br />
5.2.1 The fourth and the seventh terms . . . . . . . . . . . . . . . . . . . . . 98<br />
5.2.2 The second term . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99<br />
5.2.3 The remaining terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100<br />
5.2.4 The contribution to f NL<br />
during preheating . . . . . . . . . . . . . . . . 103<br />
5.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104<br />
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