Litim and Satz have just addressed a question I've long wondered about.(adsbygoogle = window.adsbygoogle || []).push({});

http://arxiv.org/abs/1205.4218

Limit cycles and quantum gravity

Daniel Litim, Alejandro Satz

We study renormalization group equations of quantum gravity in four dimensions. We find an ultraviolet fixed point in accordance with the asymptotic safety conjecture, and infrared fixed points corresponding to general relativity with positive, vanishing or negative cosmological constant. In a minisuperspace approximation, we additionally find a renormalization group limit cycle shielding the ultraviolet from the infrared fixed points. We discuss implications of this pattern for asymptotically safe gravity in the continuum and on the lattice.

They have an interesting bit of speculation at the end: "Finally we mention that a degenerate limit cycle oers a new scenario for asymptotic safety in that no ne-tuning of UV initial conditions is required. Instead, all trajectories enter an extended semiclassical regime and lead to a tiny positive cosmological constant in the infrared."

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Limit cycles in asymptotic safety?

**Physics Forums | Science Articles, Homework Help, Discussion**