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I'm trying to understand the connection between the $\Lambda$ from cosmology and the $\Lambda$ from QFT.

Cosmology: The cosmological constant enters the Einstein equations. In the special case of the Friedman universe it enters the Friedman equations. If we consider a spatially flat de Sitter universe, we get that

$$H_\Lambda^2=\frac{\Lambda c^2}{3}$$

therefore $\Lambda$ has the mass dimension of 2 ($[c]=0$, $[H_\Lambda]=1$).

QFT: The cut-off parameter $\Lambda$ in momentum space is such that the integration goes till $k\leq\Lambda$. Therefore $\Lambda$ has the mass dimension 1 ([k]=1).

On the other hand, both scales seem to be used interchangeably, for example here: http://www.perimeterinstitute.ca/videos/cosmological-constant To quote:

If we take the idea of the Planck length as a fundamental (minimum) scale and if additionally we impose the Cosmological Constant ($\Lambda$) as and infrared (IR) cut-off parameter.

But how can this work if the cosmological constant and the cut-off parameter have different mass dimensions?

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Trying to answer my old question myself: The cited piece is talking about an infrared cutoff, which basically amounts to giving the propagating particle a mass which appears squared in a propagator. So I think, what is meant is considering

$$\lim_{\Lambda\to 0}\int \frac{d^4p}{p^2+\Lambda}$$

and this $\Lambda$ of course has a mass dimension of 2.

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