Historic achievement in uncovering the fundamental forces of the universe at the Large Hadron Collider

Researchers at the University of Rochester, working with the CMS Collaborative, CERNhave made major progress in measuring the electroweak mixing angle, advancing 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 at the Large Hadron Collider that delve into conditions similar to those after the Big Bang. the great explosion.

Uncovering the cosmic secrets

In the quest to unlock the secrets of the universe, researchers from the University of Rochester have participated for decades in an international collaboration at the European Organization for Nuclear Research, better known as CERN.

Building on their extensive involvement at CERN, particularly within the CMS (Compact Solenoid) collaboration, the Rochester team—led by Ari Budek, the George E. Buck University Professor of Physics—recently achieved a groundbreaking feat. Their breakthrough centers on measuring the electroweak mixing angle, a crucial component of the Standard Model of particle physics. This model describes how particles interact and accurately predicts a wide range of phenomena in physics and astronomy.

“Recent measurements of the mixing angle of the electroweak force are incredibly accurate, as they were calculated from proton collisions at CERN, and they advance the understanding of particle physics,” Budick says.

the Collaboration in a content management system 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 group in the CMS Collaboration project includes principal investigators Regina DeMina, professor of physics, and Aran Garcia Bellido, associate professor of physics, along with postdoctoral research fellows 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 Herzog. Julian Marius Urdan

CERN’s legacy of discovery and innovation

Located in Geneva, Switzerland, CERN is the world’s largest particle physics laboratory, known for its pioneering 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 2012 Higgs boson discovery– An elementary particle that helps explain the origin of mass in the universe.

The collaboration involves collecting and analyzing data from the muon solenoid detector embedded in CERN’s Large Hadron Collider, the world’s largest and most powerful particle accelerator. The LHC consists of a 17-mile-long ring of superconducting magnets and underground accelerator structures that span the border between Switzerland and France.

The LHC’s primary purpose is to explore the building blocks of matter and the forces that govern them. It does this by accelerating beams of protons or ions to near the speed of light and colliding them with each other at extremely high energies. These collisions recreate conditions similar to those that existed just a fraction of a second after the Big Bang, allowing scientists to study the behavior of particles under extreme conditions.

Unified Forces Revealed

In the 19th century, scientists discovered that the different forces of electricity and magnetism are related: a changing electric field produces 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, as well as describing how electric and magnetic fields interact.

Building on this understanding, physicists discovered in the 1960s that electromagnetism is linked to another force—the weak force. The weak force operates inside the nucleus of atoms and is responsible for processes such as radioactive decay and powering the sun’s energy production. This discovery led to the development of electroweak theory, which postulates that electromagnetism and the weak force are actually low-energy manifestations of a unified force called the unified electroweak interaction. Major discoveries, such as the Higgs boson, have confirmed this concept.

Developments in electroweak interaction

The CMS team recently made one of the most precise measurements yet of this theory, by analyzing billions of proton collisions at CERN’s Large Hadron Collider. Their focus was on measuring the weak mixing angle, a parameter that describes how electromagnetism and the weak force mix together to form particles.

Previous measurements of the electroweak mixing angle have sparked controversy within the scientific community. However, the latest results are closely aligned with predictions from the Standard Model of particle physics. Rochester graduate student Rhys Tawse and postdoctoral research fellow Aliko Khokhonishvili applied new techniques to reduce the methodological uncertainties inherent in this measurement and enhance its accuracy.

Understanding the weak mixing angle sheds light on how the different forces in the universe work together on the smallest scales, deepening our understanding of the fundamental nature of matter and energy.

“The Rochester team has been developing innovative techniques and measuring these weak electrical parameters since 2010 and then implementing them at the Large Hadron Collider,” Budick says. “These new techniques have heralded a new era of accuracy testing of Standard Model predictions.”