Kinematic Varieties for Massless Particles

We study algebraic varieties that encode the kinematic data for n massless particles in d-dimensional spacetime subject to momentum conservation.

Their coordinates are  spinor brackets, which we derive from the Clifford algebra associated to the Lorentz group.  This was proposed for d=5 in the recent physics literature. Our kinematic varieties are given by polynomial constraints on tensors with both symmetric and skew symmetric slices.