Constrained BV description of string field theory

Abstract

In the conventional BV description of string field theory, the string field Φ is split as Φ = Ψ + Ψ^* where Ψ includes all states with ghost number ≤ G and describes the spacetime fields, and Ψ^* includes all states with ghost number > G and describes the spacetime antifields. A new approach is proposed here in which separate string fields Ψ and Ψ^* of unrestricted ghost number describe the spacetime fields and antifields. The string antifield Ψ^* is constrained to satisfy Ψ^* = ∂L/∂(QΨ) where L is the BV Lagrangian and Q is the worldsheet BRST operator. Dirac antibrackets are defined using this constraint, and the resulting description is equivalent to the conventional BV description for open and closed bosonic string field theory. For open superstring field theory, this constrained BV description is much simpler than the conventional BV description and allows the BV action to be expressed in the same WZW-like form as the classical action.