测量轻子和核子的深度非弹性散射(DIS),$e+p\to e+X$,可以提取部分子分布函数(PDF),它描述了组成快速运动核子的夸克、反夸克和胶子所携带的纵向动量。虽然PDF为涉及强子的微扰量子色动力学(QCD)计算提供了重要的输入,但它们并没有提供核子部分子结构的完整图像。特别是,PDF既不包含关于部分子之间的相关性的信息,也不包含关于它们的横向运动的信息。近年来,核子保持完整的硬排他过程已经成为补充这一基本一维图像的主要候选者。最简单的排斥过程是深虚康普顿散射(DVCS)或排斥产生实光子$e + p \to e + γ+ p$。这个过程是特别感兴趣的,因为它既有一个明确的实验签名,是可计算的微扰QCD。DVCS反应可以被看作是虚光子通过无色交换从质子上弹性散射,产生最终状态的实光子。在Bjorken标度体系中,QCD计算假设交换涉及两个部分子,具有不同的纵向和横向动量,在无色的配置。这些不相等的动量或偏斜是入射虚光子和出射实光子之间质量差的结果。这种偏态效应可以在广义部分子分布(GPD)的背景下解释。在这一过程中,我们研究了HERA的典型测量和CERN的COMPASS的前景,这可以为核子的夸克/胶子成像带来新的见解。
英文摘要:
Measurements of the deep-inelastic scattering (DIS) of leptons and nucleons, $e+p\to e+X$, allow the extraction of Parton Distribution Functions (PDFs) which describe the longitudinal momentum carried by the quarks, anti-quarks and gluons that make up the fast-moving nucleons. While PDFs provide crucial input to perturbative Quantum Chromodynamic (QCD) calculations of processes involving hadrons, they do not provide a complete picture of the partonic structure of nucleons. In particular, PDFs contain neither information on the correlations between partons nor on their transverse motion. Hard exclusive processes, in which the nucleon remains intact, have emerged in recent years as prime candidates to complement this essentially one dimentional picture. The simplest exclusive process is the deeply virtual Compton scattering (DVCS) or exclusive production of real photon, $e + p \to e + γ+ p$. This process is of particular interest as it has both a clear experimental signature and is calculable in perturbative QCD. The DVCS reaction can be regarded as the elastic scattering of the virtual photon off the proton via a colourless exchange, producing a real photon in the final state. In the Bjorken scaling regime, QCD calculations assume that the exchange involves two partons, having different longitudinal and transverse momenta, in a colourless configuration. These unequal momenta or skewing are a consequence of the mass difference between the incoming virtual photon and the outgoing real photon. This skewedness effect can be interpreted in the context of generalised parton distributions (GPDs). In this proceeding, we examine typical measurements from HERA and prospects for COMPASS at CERN, that can bring new insights on the quarks/gluons imaging of the nucleon.
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。
Photoproduction of a pi rhoT pair with a large invariant mass and transversity generalized parton distribution
核子的手征奇横向广义部分子分布(GPD)可以通过光生过程gamma + N -> pi + rho + N '在运动学中得到,其中介子对具有大的不变质量,末态核子具有小的横向动量,只要矢量介子产生于横向极化态.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,实验看起来可行的真实光子束的特性预期在JLab@12 GeV,并与准真实光子束在COMPASS实验。
Probing GPDs in exclusive electroproduction of dijets
Doctoral School, Institute of Physical Sciences, University of Rzeszów(热舒夫大学物理科学学院博士学院);Institute of Physical Sciences, University of Rzeszów(热舒夫大学物理科学学院);Institute of Nuclear Physics, Polish Academy of Sciences(波兰科学院核物理研究所)
Extraction of the Pion Unpolarized Quark Generalized Parton Distribution at Zero Skewness from Charge Form Factors
Dr. B.R. Ambedkar National Institute of Technology(B.R. 安贝德卡尔博士国立理工学院);Institute of Physics, Academia Sinica(中央研究院物理研究所);Moscow Institute of Physics and Technology (MIPT)(莫斯科物理技术学院(MIPT));Doaba College(多阿巴学院)
Accessing chiral-even quark generalised parton distributions in the exclusive photoproduction of a $ γπ^{\pm} $ pair with large invariant mass in both fixed-target and collider experiments
Three-dimensional imaging of hadrons with hard exclusive reactions: advances in experiment, theory, phenomenology, and lattice QCD
NRC “Kurchatov Institute” - PNPI(库尔恰托夫国家研究中心 - 彼得堡核物理研究所);INFN Laboratori Nazionali di Frascati(意大利国家核物理研究所弗拉斯卡蒂实验室);Virginia Tech(弗吉尼亚理工大学);Thomas Jefferson National Accelerator Facility(托马斯·杰斐逊国家加速器设施);Temple University(天普大学);Department of Physics, Kyungpook National University(庆北国立大学物理系);BenGurion(本古里安大学);IRB(意大利国家核物理研究所);INFN(意大利国家核物理研究所)
Exclusive vector-quarkonium photoproduction at NLO in alpha_s in collinear factorisation with evolution of the generalised parton distributions and high-energy resummation