Type II RR string fields and exotic diffeomorphisms

TL;DR

This paper explores the structure of type II string fields, revealing exotic diffeomorphisms and a duality-invariant description of Ramond-Ramond forms, with implications for understanding non-gravitating propagating degrees of freedom.

Contribution

It provides explicit expressions for gauge transformations of RR fields and analyzes the algebra of diffeomorphisms, highlighting their exotic nature and on-shell closure.

Findings

Explicit gauge transformation expressions for RR fields.

Identification of exotic diffeomorphisms in type II SFT.

Diffeomorphism algebra closes only on-shell with field-dependent structure constants.

Abstract

We study the theory of massless fields of type II strings arising from the string field theory that uses two string fields, a physical one and an extra one that allows the writing of an action, but whose degrees of freedom ultimately decouple. The mechanism allowing the description of the self-dual five-form of type IIB, anticipated by Sen, is used by the SFT to describe all Ramond-Ramond forms in type IIB and IIA in a manifestly duality-invariant way. We find explicit expressions for the leading terms in the gauge transformation of the RR fields and focus on diffeomorphisms, which are exotic for both the physical and the extra fields, perhaps as needed to describe propagating degrees of freedom that do not gravitate. The algebra of diffeomorphisms includes field-dependent structure constants and only closes on-shell, as predicted by the type II SFT gauge algebra.