Double Field Theory at Order $\alpha'$

TL;DR

This paper explores $eta'$ corrections in bosonic string theory within double field theory, revealing a new deformation of gauge structures and constructing an invariant four-derivative action that advances understanding of string $eta'$ corrections.

Contribution

It introduces a novel deformation of the Courant bracket for bosonic strings and constructs a corresponding invariant double field theory action at order $eta'$.

Findings

Deformed gauge transformations consistent with $eta'$ corrections.

Construction of a four-derivative invariant double field theory action.

Identification of non-covariant field redefinitions relating duality covariant fields.

Abstract

We investigate $\alpha'$ corrections of bosonic strings in the framework of double field theory. The previously introduced "doubled $\alpha'$-geometry" gives $\alpha'$-deformed gauge transformations arising in the Green-Schwarz anomaly cancellation mechanism but does not apply to bosonic strings. These require a different deformation of the duality-covariantized Courant bracket which governs the gauge structure. This is revealed by examining the $\alpha'$ corrections in the gauge algebra of closed string field theory. We construct a four-derivative cubic double field theory action invariant under the deformed gauge transformations, giving a first glimpse of the gauge principle underlying bosonic string $\alpha'$ corrections. The usual metric and $b$-field are related to the duality covariant fields by non-covariant field redefinitions.