Tensor-polarized structure functions: Tensor structure of deuteron in 2020's

1st Tensor Polarized Solid Target Workshop

Kumano, S.^1,2

KEK Theory Center, Institute of Particle and Nuclear Studies, KEK, 1-1, Ooho, Tsukuba, Ibaraki

305-0801, Japan^1

J-PARC Branch, KEK Theory Center, Institute of Particle and Nuclear Studies, 203-1, Shirakata, Tokai, Ibaraki

319-1106, Japan^2

关键词: Accelerator facilities;    Deep inelastic scattering;    Drell-Yan process;    Polarized distributions;    Polarized protons;    Polarized structures;    Projection Operator;    Structure functions;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/543/1/012001/pdf
DOI  :  10.1088/1742-6596/543/1/012001

来源: IOP

【 摘 要 】

We explain spin structure for a spin-one hadron, in which there are new structure functions, in addition to the ones (F1, F2, g1, g2) which exist for the spin-1/2 nucleon, associated with its tensor structure. The new structure functions are b1, b2, b3, and b4in deep inelastic scattering of a charged-lepton from a spin-one hadron such as the deuteron. Among them, twist- two functions are related by the Callan-Gross type relation b 2xb1in the Bjorken scaling limit. First, these new structure functions are introduced, and useful formulae are derived for projection operators of b1-4from a hadron tensor Wμν. Second, a sum rule is explained for b1, and possible tensor-polarized distributions are discussed by using HERMES data in order to propose future experimental measurements and to compare them with theoretical models. A proposal was approved to measure b1at the Thomas Jefferson National Accelerator Facility (JLab), so that much progress is expected for b1in the near future. Third, formalisms of polarized proton-deuteron Drell-Yan processes are explained for probing especially tensor- polarized antiquark distributions, which were suggested by the HERMES data. The studies of the tensor-polarized structure functions will open a new era in 2020's for tensor-structure studies in terms of quark and gluon degrees of freedom, which are very different from ordinary descriptions in terms of nucleons and mesons.