Bulletin of the Astronomical Society of India
The zero-signature Killing metric of a new, real-valued, 8-dimensional gauging of the conformal group accounts for the complex character of quantum mechanics. The new gauge theory gives manifolds which generalize curved, relativistic phase space. The difference in signature between the usual momentum space metric and the Killing metric of the new geometry gives rise to an imaginary proportionality constant connecting the momentumlike variables of the two spaces. Path integral quantization becomes an average over dilation factors, with the integral of the Weyl vector taking the role of the action. Minimal U(1) electromagnetic coupling is predicted.
Wheeler, J. (1997). Why quantum mechanics is complex. Bulletin of the Astronomical Society of India, (25), 591-599.