A new method to study lattice QCD at finite temperature and chemical potential

Due to the sign problem, it is exponentially difficult to study QCD on the lattice at finite chemical potential. We propose a method—an overlap improving multi-parameter reweighting technique—to alleviate this problem. We apply this method and give the phase diagram of four-flavor QCD obtained on lattices 44 and 4×63. Our results are based on O(103–104) configurations.