  Computations of screening masses in finite-temperature QCD at finite density
are plagued by the sign problem and have been performed so far with an
imaginary chemical potential. Here, we use a dual formulation of a
Polyakov-loop model which allows the determination of screening masses at real
baryon chemical potential. This is a second paper in a series devoted to a
detailed study of dual Polyakov-loop models at finite density. While the first
paper was mainly devoted to establishing the phase diagram of the model, here
we compute correlation functions of the Polyakov loops and the second-moment
correlation length at non-zero chemical potential. This enables us to evaluate
numerically the screening masses from correlations of the real and imaginary
parts of the Polyakov loops. We also compute these masses in the mean-field
approximation and compare with numerical results. In addition, we provide a
quantitative improvement of the general phase diagram presented in the first
paper.
