Date: 
August 28, 2008, 13:30  15:00 
Place: 
Seminar Room at IPMU Prefab. B, Kashiwa Campus of the University of Tokyo 
Speaker: 
Andrei Frolov (Simon Fraser University) 
Title: 
A Singularity Problem with f(R) Dark Energy

Abstract: 
I will talk about a curvature singularity problem appearing on
nonlinear level that generally plagues f(R) models that modify Einstein
gravity in the infrared. It is caused by the fact that for the effective
scalar degree of freedom, the curvature singularity is at a finite field
value and energy level, and can be easily accessed by the field dynamics
in the presence of matter. Consequences for observational viability are
grave: regular static solutions for neutron stars do not exist in many
IRmodified f(R) models. I will discuss whether the theory can be saved
by an UVcompletion.
