G. Esposito et C. Stornaiolo, LINEAR FORM OF CANONICAL GRAVITY, Nuovo cimento della Societa italiana di fisica. B, Relativity, classical and statistical physics, 111(2), 1996, pp. 271-273
Recent work in the literature has shown that general relativity can be
formulated in terms of a jet bundle which, in local coordinates, has
five entries: local coordinates on Lorentzian space-time, tetrads, con
nection one-forms, multivelocities corresponding to the tetrads and mu
ltivelocities corresponding to the connection one-forms. The derivativ
es of the Lagrangian with respect to the latter class of multivelociti
es give rise to a set of multimomenta which naturally occur in the con
straint equations. Interestingly, all the constraint equations of gene
ral relativity are linear in terms of this class of multimomenta. This
construction has been then extended to complex general relativity, wh
ere Lorentzian space-time is replaced by a four-complex-dimensional co
mplex-Riemannian manifold. One then finds a holomorphic theory where t
he familiar constraint equations are replaced by a set of equations Li
near in the holomorphic multimomenta, providing such multimomenta vani
sh on a family of two-complex-dimensional surfaces. In quantum gravity
, the problem arises to quantize a real or a holomorphic theory on the
extended space where the multimomenta can be defined.