  We study homogenous and isotropic quantum cosmology using the spinfoam
formalism of Loop Quantum Gravity (LQG). We define a coupling of a scalar field
to the 4-dimensional Lorentzian Engle-Pereira-Rovelli-Livine (EPRL) spinfoam
model. We employ the numerical method of complex critical points to investigate
the model on two different simplicial complexes: the triangulations of a single
hypercube and two connected hypercubes. We find nontrivial implications for the
effective cosmological dynamics. In the single-hypercube model, the numerical
results suggest an effective Friedmann equation with a scalar density that
contains higher-order derivatives and a scalar potential. The scalar potential
plays a role similar to a positive cosmological constant and drives an
accelerated expansion of the universe. The double-hypercubes model resembles a
symmetric cosmic bounce, and a similar effective Friedmann equation emerges
with higher-order derivative terms in the effective scalar density, whereas the
scalar potential becomes negligible.
