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: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=614396
• 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.

我的研究项目的目标是通过电磁和电弱相互作用来理解核子和原子核的基本性质。 在电磁领域，双光子交换（TPE）辐射修正的计算有助于解决使用Rosenbluth和极化转移技术测量电子-光子-核子散射形状因子之间的差异。我们小组的开创性计算集中在强子方法上，以评估模型依赖于质子的TPE振幅，包括核子共振的贡献。在过去的十年中，对TPE的实验兴趣大大增加，部分原因是它对许多精确测量有影响，例如质子半径之谜和宇称-违反电子散射。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。寻求直接识别TPE效应的实验正在几个实验室进行，我们参与提供理论支持和预测。 原子宇称破缺和电子-质子散射的精确低能实验是对标准模型直接检验的重要补充。它们还提供了有关质子结构的信息，例如其弱电荷和奇异含量。这些低能量的测量有可能给新的物理学的约束，如果关键的辐射修正是了解。特别是，与强子物理学相关的不确定性总是存在，即使在纯粹的轻子过程中也是如此。 我的研究的一个主要组成部分是旨在解开这些强子的贡献及其相关的不确定性。作为TPE计划的补充，来自两个玻色子交换的电弱辐射修正涉及低能强子（共振区）和高能强子（深非弹性和Regge区）尺度上的物理。近年来的一个重要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，如何从部分子分布函数的约束，再加上新的宇称违反电子散射的共振区的数据，可以显着减少的不确定性的修正相比，以前的估计。除了原子宇称-宇称违反和质子的弱电荷（Qweak实验），这项工作对于杰斐逊实验室和美因茨即将进行的新一代精密实验具有重要意义，这些实验利用宇称-宇称违反电子散射（例如Moller和SOLID）。 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。