High Energy Theory Seminar

I will discuss c-theorems in the context of AdS/CFT in higher derivative gravity theories. I will focus mainly on D=3 and D=4. I will show that in D=3, demanding the existence of a simple c-function leads to the recently constructed new massive gravity of Hohm, Bergshoeff and Townsend. At the four derivative order this theory has problems: when the bulk theory is unitary the boundary theory has a negative central charge. I will show how six derivative terms can potentially improve this theory and how c-theorems constrain these terms. The "fix" relies on the fact that the linearized equations of motion for fluctuations are two derivative. This constraint is then used to construct interesting higher derivative theories in D=4. All these theories have simple c-functions provided the null energy condition is satisfied for the matter sector. If time permits, I will discuss some applications in cosmology.