Electroweak interactions in hadronic systems

强子系统中的电弱相互作用

• 批准号: SAPIN-2015-00045
• 负责人: Blunden, Peter
• 金额: $ 2.77万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=718788
• 关键词: Electroweak; interactions; hadronic; systems

The objective underlying my research program is understanding the fundamental properties of nucleons and nuclei through electromagnetic and electroweak interactions. In the electromagnetic sector, calculations of two--photon exchange (TPE) radiative corrections have been instrumental in resolving the discrepancy between measurements of electron--nucleon scattering form factors using Rosenbluth and polarization-transfer techniques. Pioneering calculations by our group have focussed on a hadronic approach to evaluating the model--dependent TPE amplitudes, including the contribution of nucleon resonances. Experimental interest in TPE has grown considerably in the last decade, in part because it has implications for a number of precision measurements, such as the proton radius puzzle and parity--violating electron scattering. It is also important for extracting proton and neutron form factors, electro-production of resonances and pions, and nuclear form factors. Experiments seeking to directly identify TPE effects are underway in several laboratories, and we are involved in providing theoretical support and predictions. Precision low--energy experiments in atomic parity--violation and in parity--violating electron--proton scattering are a vital complement to direct tests of the Standard Model. They also give information about the structure of the proton, such as its weak charge and strangeness content. These low--energy measurements have the potential to give constraints on new physics, provided that the critical radiative corrections are understood. In particular, there are uncertainties associated with hadronic physics that are always present, even in purely leptonic processes. A major component of my research is aimed at unravelling these hadronic contributions and their associated uncertainties. Complementary to the TPE program, electroweak radiative corrections from two--boson exchange involve physics on both low--energy hadronic (resonance region) and high--energy (deep -inelastic and Regge region) scales. A significant advance in recent years is to reduce the model-dependence of these contributions by using dispersion relations based on data. Our work shows how constraints from parton distribution functions, together with new data on parity-violating electron scattering in the resonance region, can significantly reduce the uncertainties on the corrections compared to previous estimates. In addition to atomic parity--violation and the weak charge of the proton (the Qweak experiment), this work is significant for a new generation of upcoming precision experiments at Jefferson Lab and Mainz utilizing parity--violating electron scattering (e.g. Moller and SOLID). My research gives students excellent training in analytical and computational aspects of theoretical physics, as well as opportunities to work with international researchers.

我的研究计划的目标是通过电磁和电弱相互作用了解核子和原子核的基本性质。 在电磁领域，双光子交换 (TPE) 辐射校正的计算有助于解决使用 Rosenbluth 和偏振转移技术测量电子-核子散射形状因子之间的差异。我们小组的开创性计算主要集中在强子方法上，用于评估模型相关的 TPE 振幅，包括核子共振的贡献。在过去十年中，人们对 TPE 的实验兴趣显着增长，部分原因是它对许多精密测量具有影响，例如质子半径之谜和宇称破坏电子散射。它对于提取质子和中子形状因子、共振和π介子的电产生以及核形状因子也很重要。多个实验室正在进行旨在直接识别 TPE 效应的实验，我们参与提供理论支持和预测。 原子宇称破缺和宇称破缺电子质子散射的精密低能实验是对标准模型直接测试的重要补充。它们还提供有关质子结构的信息，例如其弱电荷和陌生含量。只要理解了关键的辐射修正，这些低能测量就有可能对新物理学产生限制。特别是，即使在纯轻子过程中，与强子物理相关的不确定性始终存在。 我研究的一个主要组成部分旨在阐明这些强子的贡献及其相关的不确定性。作为 TPE 计划的补充，双玻色子交换的电弱辐射校正涉及低能强子（共振区）和高能（深非弹性和雷格区）尺度的物理。近年来的一个重大进展是通过使用基于数据的色散关系来减少这些贡献的模型依赖性。我们的工作表明，与之前的估计相比，来自部分子分布函数的约束以及有关共振区域中宇称破坏电子散射的新数据如何能够显着降低校正的不确定性。除了原子宇称不守恒和质子的弱电荷（Qweak 实验）之外，这项工作对于杰斐逊实验室和美因茨即将进行的新一代利用宇称不守恒电子散射的精密实验（例如 Moller 和 SOLID）也具有重要意义。 我的研究为学生提供了理论物理分析和计算方面的良好培训，以及与国际研究人员合作的机会。