Nonperturbatively renormalized nucleon gluon momentum fraction in the continuum limit of lattice QCD
Zhouyou Fan (Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA); Huey-Wen Lin (Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA, Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, Michigan 48824, USA); Matthew Zeilbeck (Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA)
We present the nonperturbatively renormalized nucleon gluon momentum fraction using ensembles with flavors of highly improved staggered quarks (HISQ), generated by the MILC Collaboration. The calculation is done using clover fermions for the valence action with three pion masses, 220, 310, and 690 MeV, and three lattice spacings, 0.09, 0.12, and 0.15 fm. The renormalization is done using RI/MOM nonperturbative renormalization and using cluster-decomposition error reduction (CDER) to enhance the signal-to-noise ratio of the renormalization constant. We find the CDER technique is particularly important to improve the signal at the finer lattice ensembles where the lattice volume is larger. We extrapolate the gluon momentum fraction to the continuum-physical limit and obtain in the scheme at 2 GeV, where first error includes the statistical error and uncertainties in nonperturbative renormalization, while the latter systematic error accounts for ignoring quark mixing. Our gluon momentum fraction is consistent with other recent lattice-QCD results at physical pion mass.
