Application of the path optimization method to the sign problem in an effective model of QCD with a repulsive vector-type interaction

Understand

The path optimization method is applied to a QCD effective model with the Polyakov loop and the repulsive vector-type interaction at finite temperature and density to circumvent the model sign problem.

• We show how the path optimization method can increase the average phase factor and control the model sign problem.
• This is the first study which correctly treats the repulsive vector-type interaction in the QCD effective model with the Polyakov-loop via the Markov-chain Monte-Carlo approach.
• It is shown that the complexification of the temporal component of the gluon field and also the vector-type auxiliary field are necessary to evade the model sign problem within the standard path-integral formulation.