Ghost Sector of Vacuum String Field Theory and the Projection Equation

Abstract

We study the ghost sector of vacuum string field theory where the BRST operator Q is given by the midpoint insertion proposed by Gaiotto, Rastelli, Sen and Zwiebach. We introduce a convenient basis of half-string modes in terms of which Q takes a particularly simple form. We show that there exists a field redefinition which reduces the ghost sector field equation to a pure projection equation for string fields satisfying the constraint that the ghost number is equally divided over the left- and right halves of the string. When this constraint is imposed, vacuum string field theory can be reformulated as a $U(\infty )$ cubic matrix model. Ghost sector solutions can be constructed from projection operators on half-string Hilbert space just as in the matter sector. We construct the ghost sector equivalent of various well-known matter sector projectors such as the sliver, butterfly and nothing states.

25 pages, no figures. Typos corrected, published version

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Cited by in corpus (3)

• Tachyon Dynamics in Open String Theory
• Squeezed State Projectors in String Field Theory
• On Ghost Structure of Vacuum Superstring Field Theory