Abstract

We investigate exceptional generalised diffeomorphisms based on E (8(8)) in a geometric setting. The transformations include gauge transformations for the dual gravity field. The surprising key result, which allows for a development of a tensor formalism, is that it is possible to define field-dependent transformations containing connection, which are covariant. We solve for the spin connection and construct a curvature tensor. A geometry for the Ehlers symmetry SL(n + 1) is sketched. Some related issues are discussed.

Highlights

  • More on this in the discussion section

  • What has been done for E8 above applies in spirit to enhanced symmetries arising on dimensional reduction of gravity from 3 + n to 3 dimensions due to the appearance of a dual gravity field

  • The dual gravity field does not carry any local degrees of freedom, and it becomes clear that the restricted SL(n + 1) transformations should not be counted as removing any local degrees of freedom beyond the ones removed by the generalised diffeomorphisms

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Summary

Covariance and closure for generalised diffeomorphisms

We will revisit the concepts of covariance and closure, especially how they are linked together, for the cases known to work: ordinary diffeomorphisms, double diffeomorphisms, and exceptional diffeomorphisms for n ≤ 7. Let us first formalise what covariance and closure means The latter is simple, it means that the generators commute to a transformation with some parameter:. Covariance means, on the other hand, that the transformed vector LξV is a vector, when the vectorial transformation of both V and ξ are taken into account. ∆η(LξV M ) = − ZMN T QZT P RS + ZMP RQδSN ∂N ∂P ηRξS V Q If this vanishes, with the help of the section condition, the transformation is covariant, and L = Lfor a torsion-free connection. With the help of the section condition, the transformation is covariant, and L = Lfor a torsion-free connection This can be shown explicitly for all the cases up to n = 7 (eq (2.3) above). We should stress that the reasoning only holds for transformations constructed with naked derivatives

Beginning of a geometric construction for E8
Covariance and algebra
Covariant reducibility
Ehlers symmetry
Discussion
A Projection operators for E8 tensors
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