The cross section of the exclusive $π^0$ and $η$ electroproduction reaction $ep\to e^\prime p^\prime π^0/η$ was measured at Jefferson Lab with a 5.75-GeV electron beam and the CLAS detector. Differential cross sections $d^4σ/dtdQ^2dx_Bdϕ$ and structure functions $σ_U = σ_T+εσ_L, σ_{TT}$ and $σ_{LT}$, as functions of $t$ were obtained over a wide range of $Q^2$ and $x_B$. At low $t$, both $π^0$ and $η$ are described reasonably well by Generalized Parton Distributions (GPDs) in which chiral-odd transversity GPDs are dominant. Generalized form factors of the transversity GPDs $\langle H_T \rangle^{π,η}$ and $\langle \bar{E}_T \rangle^{π,η}$ were directly extracted from the experimental observables. The combined $π^0$ and $η$ data opens the way for the flavor decomposition of the transversity GPDs. The first ever demonstration of this decomposition was done for the transversity GPDs $H_T$ and $\bar E_T$. GPD $\bar E_T$ is connected with the density of the polarized quarks in an unpolarized nucleon in the impact parameter space. The spin density of polarized $u$ and $d$-quarks was evaluated for different values of Feynman $x$ from the GPD model tuned to described the experimental data.
Transversity Generalized Parton Distributions of $Δ$ with the Diquark Spectator Model
Southern Center for Nuclear-Science Theory, Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所南方核科学理论中心）；Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；Quark Matter Research Center, Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所夸克物质研究中心）；KEK Theory Center, Institute of Particle and Nuclear Studies, KEK（日本高能加速器研究机构粒子与核学研究所KEK理论中心）
Transversity generalized parton distributions in spin-3/2 particles
Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；Department of Mathematics, Physics, and Computer Science, Faculty of Science, Japan Women’s University（日本女子大学理学院数学、物理与计算机科学系）；Theory Center, Institute of Particle and Nuclear Studies, KEK（高能加速器研究机构粒子核研究理论中心）；Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）
虽然核子的手征偶成分研究越来越深入，但手征奇横向广义部分子分布（GPD）却几乎不为人知。这些GPD可以在实验上通过唯一的光生过程gamma + N -> pi + rho + N '获得，在运动学中，介子对具有大的不变质量，而最终核子具有小的横向动量，只要矢量介子在横向极化状态下产生。我们用微扰法计算了首阶的散射振幅。基于双分布的概念，建立了显性横向GPD H_T（x，xi，t）的简单模型。我们估计的非极化微分截面为这个过程中的运动学的Jlab和COMPASS实验。计数率表明，该实验看起来可行的真实和准真实的光子束特性预期在JLab@12 GeV，并与准真实的光子束在COMPASS实验。
