Higher-Order QED for Precision Electromagnetic Probes of Hadronic Structure

原子核是物质的主要组成部分，关于原子核性质的关键信息是从加速到数十亿电子伏能量的电子束的散射中获得的。电子加速器，例如位于托马斯杰斐逊国家加速器设施（杰斐逊实验室）的连续电子束加速器设施（CEBAF），不仅能够再现原子核的三维图像，还能够再现原子核的基本组成部分-夸克-以及它们的相互作用。需要这种高分辨率成像来获得关于指导核结构形成的尚未发现的物理学的关键信息。然而，电子探针的高分辨率可能会被量子电动力学（QED）描述的电磁效应仅比原子核内的强相互作用弱一百倍的事实所掩盖。在这方面，该项目将使电磁效应的精确校正成为可能，从而对核子和原子核的电子散射进行自洽分析。此外，PI将指导学生从事核理论的最先进的科学研究。该项目将允许发展所需的理论框架，包括高阶电磁效应到分析带电轻子散射的关键物理过程，在杰斐逊实验室和未来的电子离子对撞机进行实验研究。电子-质子和电子-核散射的高阶QED修正的影响将被详细检查。特别是，PI和他的合作者将分析核子和原子核上弹性和非弹性电子散射的多光子和辐射校正。需要考虑的特殊核反应和效应有：（a）核子的深排斥过程：由于双光子交换的效应。(b)半包含电子-核子深度非弹性散射T奇不对称性的QED圈效应。(c)电子与原子核散射的单自旋不对称性中的库仑效应。(d)质子上电子和μ子弹性散射中双光子修正的轻子质量效应。PI将开发一个用户友好的网络界面，使该领域的研究人员能够运行计算，提高电子（和μ子）散射研究的准确性。该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Crucial information about the properties of atomic nuclei, the main building blocks of matter, is obtained from scattering of electron beams accelerated to energies of billions of electron-volts. Electron accelerators such as the Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) are capable of recreating three-dimensional images of not only an atomic nucleus, but also of its elementary constituents - quarks - and their interactions. Such high resolution imaging is needed to obtain key information about the still undiscovered physics guiding formation of nuclear structure. However, the high resolution of electron probes can be obscured by the fact that electromagnetic effects described by quantum electrodynamics (QED) are only about a factor of a hundred times weaker than the strong interactions within atomic nuclei. In this context, this project will make possible precision corrections for electromagnetic effects into a self-consistent analysis of electron scattering by nucleons and nuclei. In addition, the PI will mentor students engaged in this state-of-the-art scientific research in nuclear theory. This projects will allow the development of the theoretical framework needed to include higher-order electromagnetic effects into analysis of key physics processes of charged lepton scattering to be studied experimentally at Jefferson Lab and a future Electron-Ion Collider. The effects of higher-order QED corrections for electron-proton and electron-nucleus scattering will be examined in detail. In particular, the PI and his collaborators will analyze multi-photon and radiation corrections for elastic and inelastic electron scattering on a nucleon and nuclei. Particular nuclear reactions and effects to be considered are: (a) Deep exclusive processes on a nucleon: Effects due to two-photon exchange. (b) QED loop effects for T-odd asymmetries of semi-inclusive deep-inelastic electron-nucleon scattering (SIDIS). (c) Coulomb effects in single-spin asymmetries of electron scattering from nuclei. (d) Lepton mass effects for two-photon corrections in elastic scattering of electrons and muons on a proton. The PI will develop a user-friendly web interface that will allow researchers in this field to run calculations that will improve the accuracy of electron (and muon) scattering studies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.