TY - JOUR

T1 - A study of quasi-parton distribution functions in the diquark spectator model

AU - Gamberg, Leonard

AU - Kang, Zhong Bo

AU - Vitev, Ivan

AU - Xing, Hongxi

N1 - Funding Information:
This work is supported by the U.S. Department of Energy under Contract Nos. DE-FG02-07ER41460 (L.G.) and DE-AC02-05CH11231 (Z.K., I.V. and H.X.), and in part by the LDRD program at LANL.

PY - 2015

Y1 - 2015

N2 - To facilitate lattice QCD calculations of nucleon structute, a set of quasi-parton distributions were recently introduced. These quasi-PDFs were shown to reduce to standard PDFs when the nucleon is boosted to high energies, Pz →∞. Since taking such limit is not feasible in lattice simulations, it is essential to provide guidance for what values of Pz the quasi-PDFs are good approximations of standard PDFs. Within the framework of the spectator diquark model, we evaluate both the up and down quarks' quasi-PDFs and standard PDFs for all leading-Twist distributions (unpolarized distribution fP1, helicity distribution P1, and transversity distribution hP1). We find that, for intermediate parton momentum fractions x, quasi-PDFs are good approximations to standard PDFs (within 20-30%) when Pz & 1:5-2 GeV. On the other hand, for large x 1 much larger Pz > 4 GeV is necessary to obtain a satisfactory agreement between the two sets. We further find that the Soffer positivity bound does not hold in general for quasi-PDFs.

AB - To facilitate lattice QCD calculations of nucleon structute, a set of quasi-parton distributions were recently introduced. These quasi-PDFs were shown to reduce to standard PDFs when the nucleon is boosted to high energies, Pz →∞. Since taking such limit is not feasible in lattice simulations, it is essential to provide guidance for what values of Pz the quasi-PDFs are good approximations of standard PDFs. Within the framework of the spectator diquark model, we evaluate both the up and down quarks' quasi-PDFs and standard PDFs for all leading-Twist distributions (unpolarized distribution fP1, helicity distribution P1, and transversity distribution hP1). We find that, for intermediate parton momentum fractions x, quasi-PDFs are good approximations to standard PDFs (within 20-30%) when Pz & 1:5-2 GeV. On the other hand, for large x 1 much larger Pz > 4 GeV is necessary to obtain a satisfactory agreement between the two sets. We further find that the Soffer positivity bound does not hold in general for quasi-PDFs.

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M3 - Conference article

AN - SCOPUS:84988640923

VL - 26-30-May-2015

JO - Proceedings of Science

JF - Proceedings of Science

SN - 1824-8039

M1 - 45

T2 - 2015 QCD Evolution, QCDEV 2015

Y2 - 26 May 2015 through 30 May 2015

ER -