TY  - CONF
AU  - Engelhardt, M.
AU  - Green, J.
AU  - Hasan, N.
AU  - Krieg, S.
AU  - Meinel, S.
AU  - Negele, J.
AU  - Pochinsky, A.
AU  - Syritsyn, S.
TI  - Quark orbital angular momentum in the proton evaluated using a direct derivative method
VL  - LATTICE2018
IS  - PoS LATTICE2018 (2019) 115
CY  - Trieste
PB  - SISSA
M1  - FZJ-2019-00098
M1  - PoS LATTICE2018 (2019) 115
T2  - Proceedings of Science
SP  - 7 p.
PY  - 2019
N1  - 7 pages, 3 figures, to appear in the proceedings of the 23rd International Spin Physics Symposium (SPIN2018), 10-14 September 2018, Ferrara, Italy, and in the proceedings of the 36th Annual International Symposium on Lattice Field Theory (LATTICE2018), 22-28 July 2018, Michigan State University, East Lansing, Michigan, USA
AB  - Quark orbital angular momentum (OAM) in the proton can be calculated directly given a Wigner function encoding the simultaneous distribution of quark transverse positions and momenta. This distribution can be accessed via proton matrix elements of a quark bilocal operator (the separation in which is Fourier conjugate to the quark momentum) featuring a momentum transfer (which is Fourier conjugate to the quark position). To generate the weighting by quark transverse position needed to calculate OAM, a derivative with respect to momentum transfer is consequently required. This derivative is evaluated using a direct derivative method, i.e., a method in which the momentum derivative of a correlator is directly sampled in the lattice calculation, as opposed to extracting it a posteriori from the numerical correlator data. The method removes the bias stemming from estimating the derivative a posteriori that was seen to afflict a previous exploratory calculation. Data for Ji OAM generated on a clover ensemble at pion mass $m_{\pi } = 317\, \mbox{MeV} $ are seen to agree with the result obtained via the traditional Ji sum rule method. By varying the gauge connection in the quark bilocal operator, also Jaffe-Manohar OAM is extracted, and seen to be enhanced significantly compared to Ji OAM.
T2  - 36th Annual International Symposium on Lattice Field Theory
CY  - 22 Jul 2018 - 28 Jul 2018, East Lansing, Michigan (USA)
Y2  - 22 Jul 2018 - 28 Jul 2018
M2  - East Lansing, Michigan, USA
LB  - PUB:(DE-HGF)29 ; PUB:(DE-HGF)8 ; PUB:(DE-HGF)7
UR  - https://juser.fz-juelich.de/record/859217
ER  -