The strange quark content of the nucleon $⟨N|\overline{s}s|N⟩$ is calculated in dynamical lattice QCD employing the overlap fermion formulation. For this quantity, exact chiral symmetry guaranteed by the Ginsparg-Wilson relation is crucial to avoid large contamination due to a possible operator mixing with $\overline{u}u+\overline{d}d$. Gauge configurations are generated with two dynamical flavors on a ${16}^3\times 32$ lattice at a lattice spacing $a\simeq 0.12\mathrm{fm}$. We directly calculate the relevant three-point function on the lattice including a disconnected strange quark loop utilizing the techniques of the all-to-all quark propagator and low-mode averaging. Our result $f_{T_s}=m_s⟨N|\overline{s}s|N⟩/M_N=0.032(8{)}_{\mathrm{stat}}(22{)}_{\mathrm{sys}}$, where $m_s$ and $M_N$ are strange quark and nucleon masses, is in good agreement with our previous indirect estimate using the Feynman-Hellmann theorem.

• Received 16 November 2010

DOI:https://doi.org/10.1103/PhysRevD.83.114506