We consider SU(N) Yang-Mills theory on the space R×S3 with Minkowski signature (−+++). The condition of SO(4)-invariance imposed on gauge fields yields a bosonic matrix model which is a consistent truncation of the plane wave matrix model. For matrices parametrized by a scalar φ, the Yang-Mills equations are reduced to the equation of a particle moving in the double-well potential. The classica...

The " positive square " of any tensor is presented in a universal and unified manner , valid in Lorentzian manifolds of arbitrary dimension, and independently of any (anti)-symmetry properties of the tensor. For rank-m tensors, the positive square has rank 2m. Positive here means future, that is to say, satisfying the dominant property. The standard energy-momentum and super-energy tensors are ...