The strange quark condensate in the nucleon in 2+1 flavor QCD

TL;DR

This paper computes the strange quark content of the nucleon using lattice QCD with 2+1 flavors, providing results crucial for dark matter detection interpretations.

Contribution

It introduces a lattice QCD method to evaluate the strange quark content of the nucleon including dynamical strange quarks, with continuum and chiral extrapolations.

Findings

<N| s s_bar |N> = 0.69 +- 0.07(stat) +- 0.09(sys)

m_s partial{M_N}/partial{m_s} = 59(6)(8) MeV

Results are relevant for dark matter detection experiments.

Abstract

We calculate the "strange quark content of the nucleon", <N| s s_bar |N>, which is important for interpreting the results of some dark matter detection experiments. The method is to evaluate quark-line disconnected correlations on the MILC lattice ensembles, which include the effects of dynamical strange quarks. After continuum and chiral extrapolations, the result is <N |s s_bar |N> = 0.69 +- 0.07(statistical) +- 0.09(systematic), in the modified minimal subtraction scheme (2 GeV), or for the renormalization scheme invariant form, m_s partial{M_N}/partial{m_s} = 59(6)(8) MeV.