The lower moments of nucleon structure functions in lattice QCD with physical quark masses

Abstract

We present results for the nucleon structure functions and form factors obtained from 2+1 flavor lattice QCD with physical light quark masses (𝑚 𝜋 = 135 MeV) in a large spatial extent of about 10 fm. Our calculations are performed with the PACS10 gauge configurations generated by the PACS Collaboration with the six stout-smeared O (𝑎) improved Wilson-clover quark action and Iwasaki gauge action at 𝛽 = 1.82 and 2.00 corresponding to lattice spacings of 0.085 fm and 0.064 fm respectively. The lower moments of structure functions, 𝑥 𝑢−𝑑 and 𝑥 Δ𝑢−Δ𝑑 given by the twist-2 operators being properly renormalized, are evaluated in the MS scheme at the renormalization scale of 2 GeV only at 𝛽 = 1.82, since the renormalization factors at 𝛽 = 2.00have not yet determined nonperturbatively in the RI/MOM scheme. Instead, at two lattice spacings, we evaluate appropriate ratios of 𝑔 𝐴 /𝑔 𝑉 and 𝑥 𝑢−𝑑 / 𝑥 Δ𝑢−Δ𝑑 , which are not renormalized in the continuum limit. These quantities thus can be directly compared with the experimental data without the renormalization.

Nucleon isovector tensor charge from lattice QCD with physical light quarks

“…Our results are comparable to the other lattice results, though the discretization uncertainties are not yet evaluated. Our research continues at a second, finer spacing (a = 0.064 fm), and is now in progress [15].…”