Superparticle actions and gauge fixings

A covariant quantization for the superparticle has been performed. The authors show the complete gauge fixing procedure to obtain the correct BRST operator from the action proposed by one of them. This leads to a simpler form of this operator, revealing its structure. They also re-examine several previous attempts to perform a gauge fixing procedure of the Brink-Schwarz (BS) superparticle action. These all lead to a gauge-fixed action and a BRST operator which does not produce the correct physical spectrum. They clarify this issue by using the Batalin-Vilkovisky (BV) antibracket cohomology. The same gauge-fixed action with a different BRST operator is the basis for the quantization which gives the right number of physical states. From this BRST operator a classical action is reconstructed with an infinite number of classical fields and two infinite sets of symmetries which generalize the kappa symmetry of the BS action (the doubly infinite symmetric superparticle or DISP). By performing canonical transformations they bring the DISP action in a form which is close to the BS action. They comment about the differences between the two actions.