A technical analog of the cosmological constant problem and a solution thereof

TL;DR

This paper explores a theoretical model called the framid that exhibits a problem similar to the cosmological constant's smallness, revealing complex cancellations in quantum calculations that challenge low-energy effective theories.

Contribution

It introduces the framid as a new system illustrating the cosmological constant problem and analyzes its quantum properties, highlighting mysterious cancellations.

Findings

Lorentz-invariant stress-energy expectation value in framid

One-loop computations show nontrivial cancellations

Challenges understanding from low-energy effective theory

Abstract

The near vanishing of the cosmological constant is one of the most puzzling open problems in theoretical physics. We consider a system, the so-called framid, that features a technically similar problem. Its stress-energy tensor has a Lorentz-invariant expectation value on the ground state, yet there are no standard, symmetry-based selection rules enforcing this, since the ground state spontaneously breaks boosts. We verify the Lorentz invariance of the expectation value in question with explicit one-loop computations. These, however, yield the expected result only thanks to highly nontrivial cancellations, which are quite mysterious from the low-energy effective theory viewpoint.