New density of states approaches to finite density lattice QCD

We present two new suggestions for density of states (DoS) approaches to finite density lattice QCD. Both proposals are based on the recently developed and successfully tested DoS functional fit approach (FFA) technique, which is a DoS approach for bosonic systems with a complex action problem. The two different implementations of DoS FFA we suggest for QCD make use of different representations of finite density lattice QCD in terms of suitable pseudofermion path integrals. The first proposal is based on a pseudofermion representation of the grand canonical QCD partition sum, while the second is a formulation for the canonical ensemble. We work out the details of the two proposals and discuss the results of exploratory two-dimensional test studies for free fermions at finite density, where exact reference data allow one to verify the final results and intermediate steps.