image massless superparticle covariant quantization, pure spinor BRST charge and hidden symmetries Original Research Article

We consider the covariant quantization of the image massless superparticle (M0-brane) in the spinor moving frame or twistor-like Lorentz harmonics formulation. The action involves the set of 16 constrained 32 component Majorana spinors, the spinor Lorentz harmonics image parametrizing (as homogeneous coordinates, modulo gauge symmetries) the celestial sphere image. There presence allows us to separate covariantly the first and the second class constraints of the model. We show that, after taking into account the second class constraints by means of Dirac brackets and after further reducing the first class constraints algebra, the system is described in terms of a simple BRST charge image associated to the image, image supersymmetry algebra. The study of the cohomology of this BRST operator requires a regularization by complexifying the bosonic ghosts for the κ-symmetry, image, and further reduction of the regularized cohomology problem to the one for a simpler complex BRST charge image. This latter is essentially the pure spinor BRST charge by Berkovits, but with a composite pure spinor constructed from the complex image spinor with zero norm, image, and the spinorial harmonics image. This exhibits a possible origin of the complexity (non-Hermiticity) characteristic of the Berkovits pure spinor approach.