Transverse Momentum Dependent Distributions from Lattice QCD
Final Report Abstract
The project was part of our collaboration within the Lattice Parton Collaboration (LPC) an international collaboration with members from the US, Germany, China (People’s Republic), and Taiwan. Due to security concerns with respect to High Performance Computing (HPC) this collaboration was organized such that we used exclusively German HPC systems, and the Chinese members used exclusively Chinese systems. We only collaborated for data analysis (on laptops etc.) cross checking our results as quality control measure. In this scheme on the one hand no Chinese scientist had access to German HPC centers and on the other hand we profited enormously from all the methodical developments by the Chinese and US/Chinese parts of LPC. Without this know-how, we would not have been able to perform all the analyses which entered our papers. The project is strongly linked to the planned EIC accelerator in the US. One of its main goals is to investigate in detail TMDs (Transverse Momentum Distributions or Transverse Momentum Dependent Parton Distribution Functions, also called TMDPDFs). TMDs are much more complex objects than the usual Parton Distribution Functions (PDFs) which implies also that they contain far more phenomenologically relevant information. As their experimental determination is often hardly possible, lattice determinations are the best alternative, which, however, requires much improved techniques. Quite a few approaches were proposed of which we decided to use the LaMET one. As a warm-up exercise we calculated the isovector quark transversity distribution in the nucleon, which is the least well known twist 2 quark PDF. Already this starting project gave first principle results which are of similar precision as all previous experimental an theoretical information combined. (JAM 20 and JAM 22 resulted from global fits.) Having thus mastered the techniques to perform LaMET lattice calculations we turned to the real goal of this project, namely a first principle calculation of a TMD. For this be chose the Boer-Mulders function h⊥ one of the TMDs 1 least affected by unknown power corrections. Also this project was highly successfull but is not yet published. Additional work within the project lead to four more publications.
Publications
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Mellin moments of spin dependent and independent PDFs of the pion and rho meson. Physical Review D, 105(1).
Löffler, Marius; Wein, Philipp; Wurm, Thomas; Weishäupl, Simon; Jenkins, Daniel; Rödl, Rudolf; Schäfer, Andreas & Walter, Lisa
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Lattice calculation of the intrinsic soft function and the Collins-Soper kernel. Journal of High Energy Physics, 2023(8).
Chu, Min-Huan; He, Jin-Chen; Hua, Jun; Liang, Jian; Ji, Xiangdong; Schäfer, Andreas; Shu, Hai-Tao; Su, Yushan; Walter, Lisa; Wang, Wei; Wang, Ji-Hao; Yang, Yi-Bo; Zeng, Jun & Zhang, Qi-An
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Nucleon Transversity Distribution in the Continuum and Physical Mass Limit from Lattice QCD. Physical Review Letters, 131(26).
Yao, Fei; Walter, Lisa; Chen, Jiunn-Wei; Hua, Jun; Ji, Xiangdong; Jin, Luchang; Lahrtz, Sebastian; Ma, Lingquan; Mohanta, Protick; Schäfer, Andreas; Shu, Hai-Tao; Su, Yushan; Sun, Peng; Xiong, Xiaonu; Yang, Yi-Bo & Zhang, Jian-Hui
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Universality of the Collins-Soper kernel in lattice calculations. Physical Review D, 108(7).
Shu, Hai-Tao; Schlemmer, Maximilian; Sizmann, Tobias; Vladimirov, Alexey; Walter, Lisa; Engelhardt, Michael; Schäfer, Andreas & Yang, Yi-Bo
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Unpolarized transverse momentum dependent parton distributions of the nucleon from lattice QCD. Physical Review D, 109(11).
He, Jin-Chen; Chu, Min-Huan; Hua, Jun; Ji, Xiangdong; Schäfer, Andreas; Su, Yushan; Wang, Wei; Yang, Yi-Bo; Zhang, Jian-Hui & Zhang, Qi-An
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Quark transverse spin-momentum correlation of the pion from lattice QCD: The Boer-Mulders function. Physical Review D, 111(9).
Walter, Lisa; Hua, Jun; Lahrtz, Sebastian; Ma, Lingquan; Schäfer, Andreas; Shu, Hai-Tao; Su, Yushan; Sun, Peng; Wang, Wei; Xiong, Xiaonu; Yang, Yi-Bo; Zhang, Jian-Hui & Zhang, Qi-An
