TITLE: What is the BRST-anti-BRST formalism?
QUESTION [9 upvotes]: What is the BRST-anti-BRST formalism?
Is the Sp(2) doublet the ghost, antighost pair?
Introductory accounts of this subject seem to be hard to find. I would appreciate a reference for someone who knows BRST well.

REPLY [3 votes]: To complete Igor Khavkine's answer: as explained here, in the Sp(2) covariant description the BRST and anti-BRST charges form a doublet with opposite ghost number.