Narain moduli space
= Narain moduli space
{c}
{title2=$O(d,d+16;\mathbb Z)\backslash O(d,d+16)/(O(d)\times O(d+16))$}
For a toroidally compactified <heterotic string>, the torus metric, antisymmetric tensor and gauge <Wilson lines> determine a positive $d$-plane in a charge space of signature $(d,d+16)$, modulo lattice identifications. The continuous dimension is $d(d+16)$; the coupling is an additional modulus. The three-torus case has fifty-seven shape and Wilson-line parameters.