Reuter takes hit, Hamber says Lambda can't run

[marcus]

A running G without a running lambda still leaves a lot of room for innovative AS type theories. And, evidence from the APOLLO experiment, e.g., doesn't necessarily mean much if the running of G is non-linear.

Isn't Lambda more or less analogous to the Higgs vev in electroweak theory, which also doesn't run?

I imagine some of the others will have more of an opinion about that analogy. It makes sense to me that it would not run or vary with scale/energy, but not necessarily for the reason you gave.

I don't think of Lambda as "dark energy" but simply as a one of two gravitational constants that must appear in the Einstein equation because they are allowed by the symmetry of the theory (invariance under diffeomorphisms). So in a rough sense it's analogous to a "constant of integration" that you have to put into have a correct answer in calculus. It has to appear. Einstein wrote it on LHS as a constant CURVATURE. People had no reason to expect it to be zero and when it was finally measured it turned out not to be zero. Based on Planck report, the estimate is:
1.007 x 10^-35 seconds^-2

A curvature is reciprocal area or reciprocal length squared. It just turns out to be convenient to say in reciprocal square seconds. One can convert to a possible fictitious energy by multiplying by c^2/(8 pi G)

I think the associated "dark" energy density may just be a fiction. IOW it is just a "vacuum curvature" or intrinsic curvature constant. Maybe there is a quantum geometric explanation for it. So I have no reason to expect it to run.

(Of course I could be wrong. Maybe there is some actual real energy field associated with it! Just so far no evidence of that has appeared. So far it behaves exactly like Einstein's cosmological curvature constant.)
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However, Ohwilleke, it looked to me like in Reuter's context it HAD to run. The dimensionless version of Lambda is a coupling constant λ, and the rules of the game are you solve the renormalization group equations and let the couplings (out to a certain order) run if they want to.
He did that, both dimensionless versions of G and Lambda wanted to run, and he got some very nice results on the (g, λ) plane.

To me it looks like his approach would have considerably less integrity/credibility if he artificially restricted one of the two main coupling constants. So either Hamber is wrong or this disables Reuter's approach.

Anyway that's how it looks to me. You may know differently and if so I'd be glad to hear an explanation. For the time being I'm tending to discount Asymptotic Safety QG and take more interest in Causal Sets, CDT, and some variants of LQG (tensor networks, spinorial Lqg, holonomy spinfoam ).