Extended string field theory for massless higher-spin fields

Understand

We propose a new gauge field theory which is an extension of ordinary string field theory by assembling multiple state spaces of the bosonic string.

• The theory includes higher spin fields in its massless spectrum together with the infinite tower of massive fields.
• From the theory, we can easily extract the minimal gauge invariant quadratic action for tensor fields with any symmetry.
• As examples, we explicitly derive the gauge invariant actions for some simple mixed symmetric tensor fields.