Pure spinor superstring in AdS_4 x CP^3 with unconstrained ghosts
  We construct the action for the pure spinor superstring in the coset description of AdS_4 x CP^3 superspace, using the variables which solve the pure spinor condition. As a test of the consistency of the approach, we use the background field method to verify the absence of central charge at the second order in the expansion and to show the one-loop finiteness of the effective action. 
Marisa Bonini, Alessio Camobreco
hep-th