期刊
PHYSICAL REVIEW D
卷 105, 期 1, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevD.105.014502
关键词
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资金
- Australian Commonwealth Government
- Australian Government Research Training Program (RTP) Scholarship
- STFC [ST/P000630/1, ST/G00062X/1]
- DFG [SCHI 179/8-1]
- Australian Research Council [DP190100297]
In this study, the properties of generalized parton distributions (GPDs) are determined from a lattice QCD calculation of the off-forward Compton amplitude (OFCA). By extending the Feynman-Hellmann relation to second-order matrix elements at off-forward kinematics, the OFCA can be calculated from lattice propagators computed in the presence of a background field. Using an operator product expansion, the deeply virtual part of the OFCA is parametrized in terms of the low-order Mellin moments of the GPDs. Numerical investigations are conducted to determine the form factors of the lowest two moments of the nucleon GPDs at zero-skewness kinematics. This study provides novel constraints on the x- and t-dependence of GPDs and demonstrates the viability of calculating the OFCA from first principles.
We determine the properties of generalized parton distributions (GPDs) from a lattice QCD calculation of the off-forward Compton amplitude (OFCA). By extending the Feynman-Hellmann relation to second-order matrix elements at off-forward kinematics, this amplitude can be calculated from lattice propagators computed in the presence of a background field. Using an operator product expansion, we show that the deeply virtual part of the OFCA can be parametrized in terms of the low-order Mellin moments of the GPDs. We apply this formalism to a numerical investigation for zero-skewness kinematics at two values of the soft momentum transfer, t = -1.1, -2.2 GeV2, and a pion mass of m(pi) approximate to 470 MeV. The form factors of the lowest two moments of the nucleon GPDs are determined, including the first lattice QCD determination of the n = 4 moments. Hence we demonstrate the viability of this method to calculate the OFCA from first principles, and thereby provide novel constraint on the x- and t-dependence of GPDs.
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