An Exact Algorithm for Any-flavor Lattice QCD with Kogut-Susskind Fermion

We propose an exact simulation algorithm for lattice QCD with dynamical Kogut-Susskind fermion in which the Nf -flavor fermion operator is defined as the Nf /4-throot of the Kogut-Susskind (KS) fermion operator. The algorithm is an extensionof the Polynomial Hybrid Monte Carlo (PHMC) algorithm to KS fermions. Thefractional power of the KS fermion operator is approximated with a HermitianChebyshev polynomial, with which we can construct an algorithm for any number offlavors. The error which arises from the approximation is corrected by the Kennedy-Kuti noisy Metropolis test. Numerical simulations are performed for the two-flavorcase for several lattice parameters in order to confirm the validity and the practicalfeasibility of the algorithm. In particular tests on a 164 lattice with a quark masscorresponding to mPS/mV ∼ 0.68 are successfully accomplished. We conclude thatour algorithm provides an attractive exact method for dynamical QCD simulationswith KS fermions