Séminaire / Seminar GReCO |
| « Inflationary spectra and two-mode coherent states » |
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David Campo |
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It is well understood that the temporal coherence of primordial density fluctuations, which is a prediction of inflation, can be simply implemented by neglecting the decaying mode when the mode wave length is still much larger than the Hubble radius. However this simplified treatment fails when asking more refined questions concerning, for instance, decoherence processes which could have taken place in the early universe. For similar reasons, the generic deviations from the standard distribution cannot be described in these simplified settings. To address these questions it is appropriate to use two-mode coherent states as they simply incorporate the isotropy of the distribution as well as the temporal coherence and the semi-classical character of highly amplified modes. Moreover, they provide a lowest bound for the decoherence entropy since they constitute the basis in which the density matrix rapidly becomes diagonal when taking into account weak interactions. I will present this treatment and as an illustration reexamine the question of the cosmological entropy. |
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jeudi 26 février 2004 - 11:00 Salle des séminaires Évry Schatzman Institut d'Astrophysique de Paris |
| Pages web du séminaire / Seminar's webpage |