Toward the determination of the gluon helicity distribution in the nucleon from lattice quantum chromodynamics
Colin Egerer (Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA); Bálint Joó (Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA); Joseph Karpie (Department of Physics, Columbia University, New York City, New York 10027, USA); Nikhil Karthik (Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA, Department of Physics, William and Mary, Williamsburg, Virginia 23185, USA); Tanjib Khan (BRAC University, 66 Mohakhali, Dhaka 1212, Bangladesh); et al - Show all 13 authors
We present the first exploratory lattice quantum chromodynamics (QCD) calculation of the polarized gluon Ioffe-time pseudodistribution in the nucleon. The Ioffe-time pseudodistribution provides a frame-independent and gauge-invariant framework to determine the gluon helicity in the nucleon from first principles. We employ a high-statistics computation using a lattice ensemble characterized by a 358 MeV pion mass and a 0.094 fm lattice spacing. We establish the pseudodistribution approach as a feasible method to address the proton spin puzzle with successive improvements in statistical and systematic uncertainties anticipated in the future. Within the statistical precision of our data, we find a good comparison between the lattice determined polarized gluon Ioffe-time distribution and the corresponding expectations from the state-of-the-art global analyses. We find a hint for a nonzero gluon spin contribution to the proton spin from the model-independent extraction of the gluon helicity pseudodistribution over a range of Ioffe-time, .
