Is vacuum energy really identical to the cosmological constant?

[petergreat]

When Einstein proposed the cosmological constant, it was regarded as an arbitrary constant having no connection with flat-spacetime physics (e.g. QFT to be invented later). IMHO the effective cosmological constant, in principle, should be the sum of QFT vacuum energy and Einstein's arbitrary cosmological constant. However, why is it the case that everyone equates the two concepts?

[marcus]

However, why is it the case that everyone equates the two concepts?

I think it is a mistake to equate them. For arguments to that effect see
http://arxiv.org/abs/1002.3966

[tom.stoer]

The cc as a part of the gravity / geometry sector need not be identical with DE as a part of the matter-radiation-sector. The cc could very well be a constant (simply a constant) of the gravity / geometry sector, just like the Newtonian constant G. Looking at the Einstein equations whether you put Lambda on the left (gravity) or on the right (matter) side is arbitrary. W/o a microscopic theory which explains what the cc in terms of (quantum) gravity IS or what the DE really IS one must not identify them; it could very well be that it receives contributions both from a bare constant of the gravitational sector AND from radiative corrections of the matter sector.