Precision Tests of the Standard Model and Low Energy Hadronic Interactions

对超越标准模型(BSM)的物理的搜索有三个主要方向：能量、宇宙和精确前沿。我感兴趣的是由间接搜索驱动的精度前沿，其中新粒子可能会影响可观测到的粒子，如散射截面或不对称，导致与原始标准模型(SM)预测的微小偏差，而且即将推出的几种使用强粒子束的新一代超精密测量可以检测到如此微小的影响。其中一个实验，Moller，研究违反宇称的莫勒散射，将允许确定弱混合角，不确定度为0.1%，与以前的E-158测量相比，分数精度提高了五倍。在这样的精度下，与SM的任何不一致都可能标志着BSM的物理特性。这样的精度将需要匹配的理论不确定度，这只能通过包括高达两回路的电弱计算来实现。我们计划为标准模型中的粒子建立双环电弱计算模型(2L-ECM)，并计算Moller实验所要求的电子-电子散射的宇称破坏(PV)不对称性的全套双环贡献。随后，2L-ECM应该扩展到涉及SM颗粒的广泛过程。下一阶段将包括各种假设的BSM粒子，直到单圈水平，并研究它们对电弱可观测的影响。

Search for physics beyond the Standard Model (BSM) has three major directions: energy, cosmic and precision frontiers. I am interested in the precision frontier driven by the indirect searches, where new particles could impact observables such as scattering cross section or asymmetry causing small deviations from original Standard Model (SM) predictions, and there are several upcoming new-generation, ultra-precise measurements with intense particle beams which could detect such small effect. One of such experiments, MOLLER, studying parity-violating Møller scattering, would allow a determination of the weak mixing angle with an uncertainty of 0.1%, an improvement of a factor of five in fractional precision compared with the previous E-158 measurement. At such precision, any inconsistency with the SM could signal BSM physics. Such precision will require a matching theoretical uncertainty, which can be achieved only by including electroweak calculations up to the two-loop order. We plan to construct Two-Loop Electroweak Computational Model (2L-ECM) for the particles of the Standard Model and calculate the full set of two-loop contributions to the Parity Violating (PV) asymmetry for electron-electron scattering required by the MOLLER experiment. Later, 2L-ECM should be extended to the broad spectrum of processes involving particles of SM. The next stage would be including the various hypothetical BSM particles up to one-loop level, and studying their impact on the electroweak observables.