Cc. Da Silva et Rm. Williams, Simplicial minisuperspace models in the presence of a massive scalar fieldwith arbitrary scalar coupling eta R phi(2), CLASS QUANT, 17(8), 2000, pp. 1827-1845
We consider a simplicial minisuperspace model based on a cone over the alph
a(4) triangulation of the 3-sphere, in the presence of a massive scalar fie
ld, phi, with arbitrary scalar coupling term eta R phi(2). By restricting a
ll the interior edge lengths and all the boundary edge lengths to be equiva
lent and the scalar field to be homogeneous on the 3-space, we obtain a two
-dimensional minisuperspace model {s(i), phi(i)} for what is one of the mos
t relevant triangulations of the spatial universe. We solve the two classic
al equations and find that there are both real Euclidean and Lorentzian cla
ssical solutions for any size of the boundary 3-space, alpha(4). After stud
ying the analytic properties of the action in the space of complex edge len
gths we then obtain steepest descents contours of constant imaginary action
passing through Lorentzian classical geometries giving the dominant contri
bution and yielding a convergent wavefunction of the universe. We also show
that the semi-classical wavefunctions for the Euclidean solutions associat
ed with large boundary 3-spaces are exponentially suppressed.