2022/09/19 by Xiangdong Ji, Ji, Xiangdong · 1 citation
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Lattice (hep-lat) #High Energy Physics - Phenomenology (hep-ph) #High-Energy Particle Collisions Research #Nuclear Theory (nucl-th) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.2209.09332
openalex publication_date 2022/09/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Although equivalent in the infinite-momentum limit, large-momentum effective theory (LaMET) and short-distance operator product expansion (SD-OPE) are two different approaches to extract parton distribution functions (PDFs) from coordinate-space correlation functions in large-momentum hadrons. LaMET implements a momentum-space expansion in Λ\rm QCD/[x(1-x)Pz] to directly calculate PDFs f(x) in a middle region of Bjorken x∈ [x\rm min∼ Λ\rm QCD/Pz, x\rm max∼ 1-xmin]. SD-OPE applies perturbative QCD at small Euclidean distances z to extract a range [0,λ\rm max] of leading-twist correlations, h(λ=zPz), corresponding to the Fourier transformation of PDFs. Similar to the quantum mechanical uncertainty principle, an incomplete leading-twist correlation cannot be readily converted to a momentum-space local distribution, and the methods to solve the ``inverse problem'' involve essentially modelling of the missing information beyond λ\rm max. On the other hand, short-distance correlations, along with the expected end-point asymptotics, can be used to phenomenologically fit the PDFs in the LaMET-complementary regions: x∈ [0,x\rm min] and [x\rm max, 1]. We use the recent results of the pion valence quark distribution from the ANL/BNL collaboration to demonstrate this point.