Vacuum Energy and Fine Tuning

          @misc{ pirsa_PIRSA:08090005,
            doi = {10.48660/08090005},
            url = {https://pirsa.org/08090005},
            author = {},
            keywords = {Cosmology},
            language = {en},
            title = {Vacuum Energy and Fine Tuning},
            publisher = {Perimeter Institute},
            year = {2008},
            month = {sep},
            note = {PIRSA:08090005 see, \url{https://pirsa.org}}
          }
          

Abstract

I will discuss fine tuning in modified gravity models that can account for today’s dark energy. I will introduce some models where the underlying cosmological constant may be Planck scale but starts as a redundant coupling which can be eliminated by a field redefinition. The observed vacuum energy arises when the redundancy is explicitly broken. I’ll give a recipe for constructing models that realize this mechanism and satisfy all solar system constraints on gravity, including one based on Gauss-Bonnet gravity which provides a technically natural explanation for dark energy.