Construction and Application of new Cutoff Scheures for Asymptotically Safe Quantum Gravity

• Applicant: Professor Dr. Martin Reuter
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 411018316

• Final Report Year: 2023

Final Report Abstract

A new scheme for nonperturbative analyses of quantized field systems interacting with dynamical gravity is developed, tested, and applied to concrete examples. Thereby quantum field theories are regularized by infinite sequences of quasiphysical systems comprising a well defined subset of the field’s degrees of freedom. Each such system backreacts self-consistently on the gravitational field it is exposed to. The key advantage of this approach is that the limit which removes the regularization automatically also generates the physically correct spacetime geometry prevailing in the continuum limit, i.e., the gravitational mean field the quantum states of the field prefer to “live” in. As a first application, the method is used to elucidate the so-called “cosmological constant problem” allegedly arising from the vacuum fluctuations of quantized matter fields. Considering Gaussian fields, we find that the problem disappears completely if the pertinent continuum limit is performed according to the new scheme.

Publications

• Background independent field quantization with sequences of gravity-coupled approximants. Physical Review D, 102(12).
  Becker, Maximilian & Reuter, Martin
  
• Background independent field quantization with sequences of gravity-coupled approximants. II. Metric fluctuations. Physical Review D, 104(12).
  Becker, Maximilian & Reuter, Martin
  
• Towards a Geometrization of Renormalization Group Histories in Asymptotic Safety. Universe, 7(5), 125.
  Ferrero, Renata & Reuter, Martin
  
• On the possibility of a novel (A)dS/CFT relationship emerging in Asymptotic Safety. Journal of High Energy Physics, 2022(12).
  Ferrero, Renata & Reuter, Martin
  
• The spectral geometry of de Sitter space in asymptotic safety. Journal of High Energy Physics, 2022(8).
  Ferrero, Renata & Reuter, Martin
  
• N -cutoff regularization for fields on hyperbolic space. Physical Review D, 109(2).
  Banerjee, Rudrajit; Becker, Maximilian & Ferrero, Renata