LETTER TO THE EDITOR: Real and complex connections for canonical gravity

Both real and complex connections have been used for canonical gravity: the complex connection has SL(2,C) as the gauge group, while the real connection has SU(2) as the gauge group. We show that there is an arbitrary parameter 0264-9381/14/10/002/img1 which enters in the definition of the real connection, in the Poisson brackets, and therefore in the scale of the discrete spectra one finds for areas and volumes in the corresponding quantum theory. A value for 0264-9381/14/10/002/img1 could be singled out in the quantum theory by the Hamiltonian constraint or by the rotation to the complex Ashtekar connection.