Following their extensive involvement at CERN, the University of Rochester team recently achieved “incredibly precise” measurements of the electroweak mixing angle, a key component of the Standard Model of particle physics. Credit: Samuel Joseph Hertzog; Julien Marius Ordan
Researchers from the University of Rochester, working with the CMS Collaboration at BLACKmade significant progress in measuring the electroweak mixing angle, improving our understanding of the Standard Model of particle physics.
Their work helps explain the fundamental forces of the universe, supported by experiments such as those conducted at the Large Hadron Collider, which delve into conditions similar to those after Big Bang.
Uncovering Universal Mysteries
In an effort to decode the mysteries of the universe, University of Rochester researchers have been involved in international collaboration at the European Organization for Nuclear Research, more commonly known as CERN, for decades.
Building on its extensive involvement at CERN, particularly in the Compact Muon Solenoid (CMS) collaboration, the Rochester team—led by Arie Bodke, the George E. Pake Professor of Physics—recently achieved a major milestone. Their success centers on measuring the electroweak mixing angle, a key component of the Standard Model of particle physics. This model describes how particles interact and accurately predicts a number of phenomena in physics and astronomy.
“Recent measurements of the electroweak mixing angle are incredibly precise, calculated from proton collisions at CERN, and advance the understanding of particle physics,” says Bodek.
The CMS Collaboration brings together members of the particle physics community from around the world to better understand the fundamental laws of the universe. In addition to Bodek, the Rochester cohort in the CMS Collaboration includes principal investigators Regina Demina, professor of physics, and Aran Garcia-Bellido, associate professor of physics, along with postdoctoral research associates and graduate and undergraduate students.
University of Rochester researchers have a long history of working at CERN as part of the Compact Muon Solenoid (CMS) Collaboration, including playing key roles in the discovery of the Higgs boson in 2012. Credit: Samuel Joseph Hertzog; Julien Marius Ordan
A legacy of discovery and innovation at CERN
Located in Geneva, Switzerland, CERN is the world’s largest particle physics laboratory, known for its ground-breaking discoveries and cutting-edge experiments.
Rochester researchers have a long history of working at CERN as part of the CMS Collaboration, including playing key roles in the 2012 discovery of the Higgs boson – an elementary particle that helps explain the origin of matter in the universe.
The collaboration involves the collection and analysis of data collected from the Compact Muon Solenoid Detector at the Large Hadron Collider (LHC) at CERN, the largest and most powerful particle accelerator in the world. The LHC consists of a 17-mile-long ring of superconducting magnets and accelerator structures built underground and spanning the border between Switzerland and France.
The primary purpose of the LHC is to investigate the fundamental building blocks of matter and the forces that govern them. It achieves this by accelerating beams of protons or ions to nearly the speed of light and smashing them together at extremely high energies. These collisions recreate conditions similar to those that existed a fraction of a second after the Big Bang, allowing scientists to study the behavior of particles in extreme conditions.
Unraveling the united forces
In the 19th century, scientists discovered that the various forces of electricity and magnetism are interconnected: a changing electric field creates a magnetic field and vice versa. This discovery formed the basis of electromagnetism, which describes light as a wave and explains many phenomena in optics, along with describing the interaction of electric and magnetic fields.
Based on this understanding, physicists discovered in the 1960s that electromagnetism is associated with another force—the weak force. The weak force operates in the nucleus of atoms and is responsible for processes such as radioactive decay and drives the production of solar energy. This discovery led to the development of the electroweak theory, which postulates that electromagnetism and the weak force are actually low-energy manifestations of a unified force called the unified electroweak interaction. Key discoveries such as the Higgs boson confirmed this concept.
Advances in Electroweak Interaction
The CMS Collaboration recently made one of the most precise measurements yet of this theory by analyzing billions of proton-proton collisions at the LHC at CERN. They focused on measuring the weak mixing angle, a parameter describing how electromagnetism and the weak force mix to form particles.
Previous measurements of the electroweak mixing angle have sparked debate in the scientific community. However, the latest findings closely match predictions from the Standard Model of particle physics. Rochester graduate student Rhys Taus and postdoctoral researcher Aleko Khukhunaishvili implemented new techniques to minimize the systematic uncertainties associated with this measurement, increasing its accuracy.
Understanding weak-angle mixing sheds light on how the various forces in the universe work together at the smallest scales and deepens understanding of the fundamental nature of matter and energy.
“The Rochester team has been developing innovative techniques and measuring these electroweak parameters since 2010 and then implementing them at the Large Hadron Collider,” says Bodek. “These new techniques ushered in a new era of tests of the accuracy of Standard Model predictions.”