천체입자물리 및 우주론 이론 연구실에서 인도  The Institute of Mathematical Sciences의 Rathul Nath Raveendran 박사님을 초청하여 아래와 같이 세미나를 개최합니다.

학과 구성원 여러분의 많은 참석을 부탁 드립니다.

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○ Date/time: 2019. 08. 26(Mon) 14:00

○ Place: 기초과학연구소 세미나실(31317호)

○ Speaker: Dr. Rathul Nath Raveendran (The Institute of Mathematical Sciences )

○ Title: Constructing viable models of bouncing scenarios

○ Abstract:  The inflationary and the bouncing scenarios constitute two competing paradigms for the generation of perturbations in the early universe.
In this talk, I will discuss certain aspects of bouncing scenarios driven by scalar fields. First, I will discuss how to construct a model involving two scalar fields to drive the symmetric matter bounce and study the evolution of the scalar perturbations in the model. In this model, I will show that, while the scalar and tensor perturbation spectra are scale invariant over scales of cosmological interest, the tensor-to-scalar ratio proves to be much smaller than the current upper bound from the observations of the CMB anisotropies. While nearly scale invariant primordial spectra are remarkably consistent with the cosmological data, it has been repeatedly noticed that specific features in the power spectra lead to a better fit to the data. I will also demonstrate that ekpyrotic bouncing scenarios can generate specific features that have been considered in the context of inflation. In the last part of the talk, I will compare and contrast the quantum-to-classical transition of the primordial perturbations in the inflationary and bouncing scenarios.