Dor Gabay and Sijo K. Joseph of Tel Aviv University, in Israel, have a new paper (arXiv:1801.00161), currently submitted for peer review, that they would like to discuss with the FQXi Community.
Here is Dr Joseph's introduction:
The value of the cosmological constant obtained using the General Theory of Relativity and the value suggested by Quantum Field Theory disagree greatly, still this is an unresolved problem in Physics called the cosmological constant problem. Einstein's General theory of relativity is purely a geometric theory, while quantum theory is a probabilistic theory. The way to understand quantum theory in a cosmological context is to reformulate it from a probabilistic theory to a geometrical one. Treating Einstein's theory and the quantum theory on an equal geometrical footing, both theories can be merged together with a Lagrange multiplier. Then the resulting theory can give the cosmological constant contribution from a scalar field and the Lagrange multiplier. The key underlying idea is, one should bring quantum theory into a geometric form before merging the theory with General Theory of Relativity, then both theories are consistent and the cosmological constant can be easily evaluated. These results are highly important, since nobody were able to predict the value of the cosmological constant using quantum mechanical arguments. These results also suggest that we need to go beyond Einstein's General Theory of Relativity to Scalar-Tensor theory to incorporate quantum mechanical effects.