  We offer the Skyrme model on a lattice as an effective field theory - fully
quantized - of baryon-meson interactions at temperatures below the chiral phase
transition. We define a local topological density that involves the volumes of
tetrahedra in the target space S^3 and we make use of Coxeter's formula for the
Schlafli function to implement it. This permits us to calculate the mean-square
radius of a skyrmion in the three-dimensional lattice Skyrme model, which may
be viewed as a Ginzburg-Landau effective theory for the full quantum theory at
finite temperature. We find that, contrary to expectations, the skyrmion
shrinks as quantum and thermal fluctuations are enhanced. We ascribe this to a
large number of metastable states that become accessible as the temperature is
raised.
