Physical Point Simulation in 2+1 Flavor Lattice QCD

TL;DR

This paper reports on a direct simulation of 2+1 flavor lattice QCD at the physical point, utilizing advanced algorithms to accurately determine hadron properties and quark masses without chiral extrapolation.

Contribution

The study introduces a combination of mass-preconditioned domain-decomposed HMC and reweighting techniques enabling direct physical point simulations in lattice QCD.

Findings

Accurate hadron spectrum at physical quark masses

Determination of quark masses and decay constants

Comparison with previous chiral extrapolation results

Abstract

We present the results of the physical point simulation in 2+1 flavor lattice QCD with the nonperturbatively $O(a)$-improved Wilson quark action and the Iwasaki gauge action at $\beta=1.9$ on a $32^3 \times 64$ lattice. The physical quark masses together with the lattice spacing is determined with $m_\pi$, $m_K$ and $m_\Omega$ as physical inputs. There are two key algorithmic ingredients to make possible the direct simulation at the physical point: One is the mass-preconditioned domain-decomposed HMC algorithm to reduce the computational cost. The other is the reweighting technique to adjust the hopping parameters exactly to the physical point. The physics results include the hadron spectrum, the quark masses and the pseudoscalar meson decay constants. The renormalization factors are nonperturbatively evaluated with the Schr{\"o}dinger functional method. The results are compared with the previous ones obtained by the chiral extrapolation method.