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An enhanced CMB power spectrum at large scale?

by Dr. Francesco Pessina (Dipartimento di Fisica - Napoli)

Jul 25, 2013 from 12:00 AM to 02:00 PM

Where Aula Teorici - Irnerio

Contact Name Dr. Gian Paolo Vacca

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Abstract: Recent work in the literature has investigated whether small quantum gravitational effects can be observed in the anisotropy spectrum of the cosmic microwave background radiation. For this purpose, a massive scalar field in a spatially flat Friedmann–Lemaitre–Robertson–Walker universe has been considered, and its fluctuations have been decomposed into Fourier modes. Eventually, a Jeffreys–Wentzel–Kramers–Brillouin approach leads to nonlinear differential equations for the evaluation of the various orders in the asymptotic expansion of the full wave function in powers of the Planck mass squared. Even at zeroth order in the Planck mass squared, new features are here found, i.e. the general integral of the nonlinear differential equation encountered at the beginning of the analysis is obtained in exact form in terms of amplitude and phase of a complex parameter. The resulting quantum correction to the CMB power spectrum is evaluated in detail, and it shows that there should be an enhancement of power at large scales. This holds both for an inflationary stage of finite duration and in the idealized case of eternal inflation. A detailed investigation of the unitarity violation issue is also performed.