Reflection positivity in simplicial gravity

Reflection Positivity and Monotonicity

We prove general reflection positivity results for both scalar fields and Dirac fields on a Riemannian manifold, and comment on applications to quantum field theory. As another application, we prove the inequality CD ≤ CN between Dirichlet and Neumann covariance operators on a manifold with a reflection.

Simplicial Quantum Gravity

Quantum gravity on a lattice in a formulation due to Regge is reviewed in view of possible applications to renormalizable asymptoti-cally free higher derivative theories of gravity.

Simplicial Quantum Gravity

Reflection Positivity for Majoranas

We establish reflection positivity for Gibbs trace states defined by a certain class of Hamiltonians that describe the interaction of Majoranas on a lattice. These Hamiltonians may include many-body interactions, as long as the signs of the associated coupling constants satisfy certain restrictions. We show that reflection positivity holds on an even subalgebra of Majoranas.

Gauge invariance in simplicial gravity

The issue of local gauge invariance in the simplicial lattice formulation of gravity is examined. We exhibit explicitly, both in the weak-field expansion about flat space, and subsequently for arbitrarily triangulated background manifolds, the exact local gauge invariance of the gravitational action, which includes in general both cosmological constant and curvature-squared terms. We show that ...