Primordial Tensor Correlations from Effective Field Theory Approach

Dr Toshifumi Noumi
RIKEN Nishina Center

 

4 December 2013 (Wednesday)
10:00 - 11:00 am
IAS4042, 4/F, Lo Ka Chung Building, Lee Shau Kee Campus, HKUST

Abstract:

Primordial curvature fluctuations generated by inflation can be thought of as a seed of structures in the universe and correlation functions of such curvature perturbations play an important role for the test of inflationary scenarios. From the symmetry point of view, inflationary dynamics can be characterized by the spontaneous breakdown of time-diffeomorphism invariance due to the time-dependent background evolution. In the effective field theory approach, the generic action for curvature perturbations can be constructed based on this symmetry breaking structure and, in particular, scalar curvature perturbations (adiabatic perturbations) can be interpreted as the Goldstone modes associated with the breaking of time-diffeomorphism invariance. By virtue of this interpretation as Goldstone modes, it is known for example that there is a negative correlation between the sound speed of adiabatic perturbations and the scalar bispectra: large scalar non-Gaussianities can be obtained for the small scalar sound speed. In this talk, the speaker will discuss how such a relation between dispersion relations and bispectra can be extended to the tensor sector.

The seminar is free and open to the public. No registration is required. Seating is on a first-come first-served basis.

HKUST Jockey Club Institute for Advanced Study
URL: http://ias.ust.hk
Enquiries: ias@ust.hk / 2358 5912