TY - JOUR
T1 - Quark orbital angular momentum in the proton evaluated using a direct derivative method
AU - Engelhardt, M.
AU - Green, J.
AU - Hasan, N.
AU - Krieg, S.
AU - Meinel, S.
AU - Negele, J.
AU - Pochinsky, A.
AU - Syritsyn, S.
N1 - Funding Information:
This work benefited from fruitful discussions with M. Burkardt, S. Liuti and B. Musch. Computations were performed using resources provided by the U.S. DOE Office of Science through the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility, under Contract No. DE-AC02-05CH11231, as well as through facilities of the USQCD Collaboration at Fermilab, employing the Chroma [20] and Qlua software suites. R. Edwards, B. Joó and K. Orginos are acknowledged for providing the clover ensemble analyzed in this work, which was generated using resources provided by XSEDE (supported by National Science Foundation Grant No. ACI-1053575). S.M. is supported by the U.S. DOE, Office of Science, Office of High Energy Physics under Award Number DE-SC0009913. S.S. and S.M. also acknowledge support by the RHIC Physics Fellow Program of the RIKEN BNL Research Center. M.E., J.N., and A.P. are supported by the U.S. DOE, Office of Science, Office of Nuclear Physics through grants numbered DE-FG02-96ER40965, DE-SC-0011090 and DE-FC02-06ER41444 respectively. This work was furthermore supported by the U.S. DOE through the TMD Topical Collaboration.
Funding Information:
This work benefited from fruitful discussions with M. Burkardt, S. Liuti and B. Musch. Computations were performed using resources provided by the U.S. DOE Office of Science through the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility, under Contract No. DE-AC02-05CH11231, as well as through facilities of the USQCD Collaboration at Fermilab, employing the Chroma [20] and Qlua software suites. R. Edwards, B. Jo? and K. Orginos are acknowledged for providing the clover ensemble analyzed in this work, which was generated using resources provided by XSEDE (supported by National Science Foundation Grant No. ACI-1053575). S.M. is supported by the U.S. DOE, Office of Science, Office of High Energy Physics under Award Number DE-SC0009913. S.S. and S.M. also acknowledge support by the RHIC Physics Fellow Program of the RIKEN BNL Research Center. M.E., J.N., and A.P. are supported by the U.S. DOE, Office of Science, Office of Nuclear Physics through grants numbered DE-FG02-96ER40965, DE-SC-0011090 and DE-FC02-06ER41444 respectively. This work was furthermore supported by the U.S. DOE through the TMD Topical Collaboration.
PY - 2018
Y1 - 2018
N2 - 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 mπ = 317 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.
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 mπ = 317 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.
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M3 - Conference article
AN - SCOPUS:85072010099
VL - 346
JO - Proceedings of Science
JF - Proceedings of Science
SN - 1824-8039
T2 - 23rd International Spin Physics Symposium, SPIN 2018
Y2 - 10 September 2018 through 14 September 2018
ER -