PIRSA:22030030 Scientific Series Quantum Gravity

DOI10.48660/22030030

Series: Quantum Gravity

Yamada, M. (2022). Asymptotically safe gravity and beyond. Perimeter Institute. https://pirsa.org/22030030

Yamada, Masatoshi. Asymptotically safe gravity and beyond. Perimeter Institute, Mar. 31, 2022, https://pirsa.org/22030030 

@misc{ pirsa_PIRSA:22030030,
  doi = {10.48660/22030030},
  url = {https://pirsa.org/22030030},
  author = {Yamada, Masatoshi},
  keywords = {Quantum Gravity},
  language = {en},
  title = {Asymptotically safe gravity and beyond},
  publisher = {Perimeter Institute},
  year = {2022},
  month = {mar},
  note = {PIRSA:22030030 see, \url{https://pirsa.org}}
}

Abstract

In this talk, we first introduce the basic idea of asymptotic safety and discuss its application to quantum gravity. We compute non-perturbative flow equations for the couplings of quantum gravity in fourth order of a derivative expansion. It is shown that the beta functions admit two possible fixed points: One is the asymptotically safe fixed point, and the other is the asymptotically free one. The corresponding critical exponents to these fixed points are evaluated.

Next, we argue that asymptotically safe gravity could be an effective theory emerging from the spontaneous symmetry breaking in an ultraviolet (UV) theory. We consider a UV theory invariant under SO(4) local Lorentz symmetry and diffeomorphism. In particular, we impose the degenerate limit (zero eigenvalues of vierbein) on the action and then show that only spinor fields can be dynamical. We will discuss prospects whether or not this UV theory could be a fundamental theory underlying asymptotically safe gravity.

Zoom Link: https://pitp.zoom.us/j/94422371986?pwd=a25pS3cyUmJkNWJHL3hic1NhNlozQT09

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