Jl. Gervais, T-duality between perturbative characters of E-8 circle times E-8 and SO(32) heterotic strings compactified on a circle, NUCL PHYS B, 546(1-2), 1999, pp. 135-154
Characters of E-8 x E-8 and SO(32) heterotic strings involving the full int
ernal symmetry Cartan subalgebra generators are defined after circle compac
tification so that they are T-dual. The novel point, as compared with an ea
rlier study of the type II case, is the appearance of Wilson lines. Using S
O(17, 1) transformations between the weight lattices reveals the existence
of an intermediate theory where T-duality transformations are disentangled
from the internal symmetry. This intermediate theory corresponds to a sort
of twisted compactification of a novel type. Its modular invariance follows
from an interesting interplay between three representations of the modular
group. (C) 1999 Published by Elsevier Science B.V.