Title: [NCTS-NTU String Theory Seminar] The cosmological constant problem and covariant quantization of unimodular gravity
Speaker: Prof. Nobuyoshi Ohta (National Central Univ.)
Time: Apr. 15th, 2022 (Fri) 14:30-15:30 (Taiwan time)
Venue: Rm. 803, Dept. of Physics, NTU

Abstract:
The recent cosmological observation indicates that our universe is
undergoing accelerating expansion. This may be explained by assuming
a very tiny cosmological constant, but it is unnatural to assume it
in general relativity. Unimodular gravity is an interesting theory that
may explain why the cosmological constant is so small. However there
remains a puzzle if the theory is equivalent to general relativity,
which is successful in describing low-energy gravitational phenomena,
modulo cosmological constant, in particular in the covariant quantization.
We discuss the covariant quantization of unimodular gravity and show
that it is indeed equivalent to general relativity.