Singularity of the density of states in the two-dimensional Hubbard model from finite-size scaling of Yang-Lee zeros

A finite-size scaling is applied to the Yang-Lee zeros of the grand canonical partition function for the two-dimensional Hubbard model in the complex chemical potential plane. The logarithmic scaling of the imaginary part of the zeros with the system size indicates a singular dependence of the carrier density on the chemical potential. Our analysis points to a second-order phase transition with critical exponent 1/delta(=)1/2+/-1/3 which leads to a divergence of the electronic susceptibility. We interpret these results as reflecting the singular behavior of the density of states in the quasiparticle spectrum.