Probing nucleon strange and charm distributions with lattice QCD

Understand

We present the first lattice-QCD calculation of the unpolarized strange and charm parton distribution functions using large-momentum effective theory (LaMET).

• We use a lattice ensemble with 2+1+1 flavors of highly improved staggered quarks (HISQ) generated by MILC collaboration, with lattice spacing $a\approx 0.12$ fm and $M_\pi \approx 310$ MeV, and clover valence fermions with two valence pion masses: 310 and 690 MeV.
• We use momentum-smeared sources to improve the signal up to nucleon boost momentum $P_z=2.18$ GeV, and determine nonperturbative renormalization factors in RI/MOM scheme.
• We compare our lattice results with the matrix elements obtained from matching the PDFs from CT18NNLO and NNPDF3.1NNLO global fits.