Physicists from the National Laboratory of Thomas Jefferson Lab, part of the US Department of Energy, have made a groundbreaking discovery in measuring the polarization of electronic beams. The accuracy record, which had stood for almost 30 years since the SLAC Large Detector experiment (SLD), was shattered at the National Laboratory of SLAC accelerators. The new accuracy in measuring the polarization of electronic beams is an impressive 0.36%, surpassing the previous record of 0.5%. This breakthrough paves the way for future experiments at Jefferson Lab, such as MOLLER (Measurement of A Lepton-Lepton Electroweak Reaction), which aims to study the weak charge of the electron and validate the standard model of elementary particle physics. You can read more about the study here.
The improvement in measuring the polarization of electronic beams is crucial in fundamental science. Electron polarization is a vital parameter in experiments that delve into the structure of substances on a microscopic level, allowing for more accurate testing of theoretical predictions and exploration of physics beyond the standard model. While the standard model serves as the foundation of modern elementary particle physics, encompassing all known fundamental interactions excluding gravity, it does have its limitations. The standard model fails to address the enigma of dark matter and the issue of CP-symmetry violations.
Experiments like Moller offer a unique chance to tackle these unresolved matters by providing physical measurements that can pinpoint deviations from the theoretical predictions of the standard model. These deviations could indicate the presence of new particles or interactions, marking a significant stride towards a fuller comprehension of the fundamental laws of nature.
The groundbreaking achievement in enhancing the accuracy of polarization measurement also holds significance for the forthcoming electron-ion collider (EIC) and other experiments like Solidal Large Intensity Device, to be conducted at Jefferson Lab. These experiments focus on studying the internal structure of protons and heavy atomic nuclei, shedding light on the forces responsible for their cohesion and offering fresh insights into the makeup of matter.