Theory HEP Seminar

A new renormalized stress-energy tensor and the cosmological constant problem

Yigit Yarnic

Perimeter Institute

We modify the semiclassical Einstein equation by subtracting the instantaneous ground state expectation value of the stress-energy tensor. In our proposal, only the energetic excitation above the instantaneous ground state contributes as a source to gravity. This ansatz is independent of any criterion for identifying the vacuum state and respects the Bianchi identity. In this way, the cosmological constant becomes protected from renormalization at the UV scale, offering a solution to the cosmological constant problem. Our scheme is so far limited to FRW backgrounds.