No-Ghost Theorem for Neveu-Schwarz String in 0-Picture

TL;DR

This paper proves the no-ghost theorem for Neveu-Schwarz strings in the 0-picture, establishing a correspondence with the conventional picture and exploring implications for superstring field theory.

Contribution

It provides a direct proof of the no-ghost theorem in the 0-picture and introduces a new inverse picture changing operator.

Findings

Confirmed the correspondence between physical states in 0-picture and -1-picture.

Identified the need for a non-trivial metric to define a positive semi-definite norm.

Discussed the potential for constructing a new gauge invariant superstring field theory.

Abstract

The no-ghost theorem for Neveu-Schwarz string is directly proved in 0-picture. The one-to-one correspondence between physical states in 0-picture and those in the conventional (-1)-picture are confirmed. It is shown that a non-trivial metric consistent with the BRST cohomology is needed to define a positive semi-definite norm in the physical Hilbert space. As a by-product, we find a new inverse picture changing operator, which is non-covariant but has non-singular operator product with itself. A possibility to construct a new gauge invariant superstring field theory is discussed.