Dual BRST Symmetry in QED

We discuss local and covariant dual BRST symmetry and its consequences in two-dimensional quantum electrodynamics (QED). With the help of BRSTand dual BRST charges, we explore the BRST cohomology of physical states in the quantum Hilbert space. The algebra between conserved and nilpotent BRSTand dual BRST charges leads to the existence of a BRST-extended Casimir operator. The Hodge decomposition theorem is expressed in terms of these operators which refine the BRST cohomology of the physical states. PACS numbers: 11.30.Pb, 02.20.+b, 12.20.-m, ∗E-mail address: [email protected]