Abstract

We construct the off-shell recursion for gravity and the graviton current for the perturbative double field theory (DFT). We first formulate the perturbative DFT, which is equivalent but simpler to perturbative general relativity, to all-orders in fluctuations of generalised metric. The perturbative action and equations of motion (EoM) are derived to arbitrary order for pure gravity case. We then derive the graviton off-shell recursion, the gravity counterpart of the Berends-Giele recursion in Yang-Mills theory, through the so-called perturbiner method using the EoM of the perturbative DFT. We solve the recursion iteratively and obtain the graviton off-shell currents explicitly. We then discuss the classical double copy for the off-shell currents. We present the current KLT relation for gravity by extending the result proposed by Mizera and Skrzypek for the non-gravitational effective field theories. The relation represents graviton currents by squaring gluon currents with the KLT kernel up to gauge transformation and regular terms that do not have any pole. Finally we discuss the off-shell conservation of currents for nonlinear gauge choices.

Highlights

  • As an alternative theory of gravity, double field theory (DFT) reformulates the closed string low energy effective field theory by requiring the manifest O(D, D) T-duality [5–11]

  • This paper presents the classical double copy for graviton off-shell currents

  • We have found the explicit field redefinition between the perturbation of the generalised metric and metric perturbations in GR. This shows the equivalence between perturbative DFT and the perturbative GR

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Summary

Perturbation of double field theory

We construct the perturbation theory of double field theory (DFT) as an alternative tool to the perturbative GR. We first analyse the structure of the perturbation of the generalised metric by solving the O(D, D) constraint exactly. We find the relation between the generalised metric perturbation and the metric perturbation in GR. We construct action and EoM of the perturbative DFT for pure gravity including all-orders in. We discuss the gauge choice of the generalised metric, which is closely related to the de Donder gauge fixing in perturbative GR

Perturbation of the generalised metric
Perturbation of DFT equations of motion for pure gravity
Off-shell recursion for gravity
Perturbiner method for Yang-Mills theory
Perturbiner expansion for DFT
Solving the recursions and the classical double copy for currents
Current KLT relation
Currents in the spinor-helicity basis
Class 1
Class 2
Conservation of the off-shell currents
Conservation of gluon currents in Gervais-Neveu gauge condition
Conservation of the graviton currents
Conclusion
A Explicit form of the graviton recursions
B Gluon off-shell currents in the Lorentz gauge
C Gauge transformation terms in the rank-4 current KLT relation
Full Text
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