# Would asymptomatic safe gravity grow weaker like QCD?

1. Aug 30, 2015

### kodama

QCD is asymptomatic safe well known to grow weaker at higher energies.

if gravity is also asymptotic safe would it grow weaker at higher energies instead of stronger as predicted by classical GR?

if not, is it possible there is a quantum gravity theory that like QCD grows weaker at higher energies?

i.e at low energies it is described as GR, but at high energies it is QCD-like and grows weaker

QCD-gluons and gravitons are non-abelian self-interacting bosons

2. Aug 30, 2015

### Physics Monkey

As far as I understand the proposal, what one requires is that the system approaches a UV fixed point at high energies. The fixed point could be non-interacting but generically I would expect some order one dimensionless interaction strength. Although I haven't thought carefully about it, I would guess that in the case of gravity one could argue against weak interactions at high energy as incompatible with the holographic principle.

EDIT: More generally, I don't understand much about how non-perturbative aspects of gravity - black holes, holography, etc. - are supposed to work in the asymptotic safety scenario.

3. Aug 30, 2015

### marcus

In partial answer, in the most recent review paper I know of on AsymSafe QG, on page 36 it says
==quote http://arxiv.org/pdf/1202.2274.pdf ==
Hence for k → ∞ and d > 2 the dimensionful Newton constant vanishes while the cosmological constant diverges.
==endquote==

The parameter k is like a wave number, an inverse length. So for low k (the IR or coarse scale) the Newton constant G and the cosmo constant Λ are the usual G and Λ.

A commonly discussed form of the theory concerns dimensionless versions gk and λk which approach a fixed point g*, λ*

As for the dimensionful versions, Gk = gk/k2 goes to zero as g*/k2 and Λk = λkk2 diverges as λ*k2

4. Aug 30, 2015

### kodama

maybe the holographic principle is wrong?

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