  The dual form of the massless Schwinger model on the lattice overcomes the
complex action problems from two sources: a topological term, as well as
non-zero chemical potential, making these physically interesting cases
accessible to Monte Carlo simulations. The partition function is represented as
a sum over fermion loops, dimers and plaquette-surfaces such that all
contributions are real and positive. However, these new variables constitute a
highly constrained system and suitable update strategies have to be developed.
In this exploratory study we present an approach based on locally growing
plaquette-surfaces surrounded by fermion loop segments combined with a worm
based strategy for updating chains of dimers, as well as winding fermion loops.
The update strategy is checked with conventional simulations as well as
reference data from exact summation on small volumes and we discuss some
physical implications of the results.
