Building on 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 CERNhave made significant progress in measuring the electroweak mixing angle, allowing us to better understand 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 the Big Bang.
Revealing universal mysteries
In the quest to unravel the mysteries of the universe, researchers from the University of Rochester have been involved for decades in international collaborations at the European Organization for Nuclear Research, better known as CERN.
Building on their extensive involvement with CERN, particularly within the CMS (Compact Muon Solenoid) Collaboration, the Rochester team – led by Arie Bodek, the George E. Pake Professor of Physics – recently achieved a groundbreaking milestone. Their achievement focuses on measuring the electroweak mixing angle, a crucial part of the Standard Model of particle physics. This model describes how particles interact and accurately predicts a plethora of phenomena in physics and astronomy.
“The recent measurements of the electroweak mixing angle are incredibly precise, calculated from proton collisions at CERN, and enhance 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 basic laws of the universe. In addition to Bodek, the Rochester cohort of 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.
Researchers from the University of Rochester have a long history of work at CERN as part of the Compact Muon Solenoid (CMS) Collaboration, including playing a key role 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 groundbreaking discoveries and groundbreaking experiments.
Rochester researchers have a long history of work at CERN as part of the CMS collaboration. They played an important role in the 2012 discovery of the Higgs boson, an elementary particle that helps explain the origin of mass in the universe.
The collaboration’s work involves collecting and analyzing data collected by the Compact Muon Solenoid detector at CERN’s Large Hadron Collider (LHC), the world’s largest and most powerful particle accelerator. The LHC consists of a 17-mile-long ring of superconducting magnets and accelerating structures built underground, spanning the border between Switzerland and France.
The primary goal of the LHC is to study the fundamental building blocks of matter and the forces that govern them. This is achieved by accelerating beams of protons or ions to nearly the speed of light and colliding them at extremely high energies. These collisions create conditions similar to those that existed a fraction of a second after the Big Bang, allowing scientists to study the behavior of particles under extreme conditions.
Unraveling united forces
In the 19th century, scientists discovered that the different forces of electricity and magnetism were linked: a changing electric field produces a magnetic field and vice versa. The discovery formed the basis of electromagnetism, which describes light as a wave and explains many phenomena in optics, along with the way electric and magnetic fields interact.
Building on this insight, physicists in the 1960s discovered that electromagnetism is linked to another force: the weak force. The weak force acts in the atomic nucleus and is responsible for processes such as radioactive decay and powering the sun’s energy production. This revelation led to the development of the electroweak theory, which states 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.
Advances in electroweak interaction
The CMS Collaboration recently made one of the most precise measurements to date of this theory, by analyzing billions of proton-proton collisions at the LHC at CERN. Their focus was on measuring the weak mixing angle, a parameter that describes how electromagnetism and the weak force merge to create particles.
Previous measurements of the electroweak mixing angle have sparked debate within the scientific community. However, the latest findings closely match predictions of the Standard Model of particle physics. Rochester graduate Rhys Taus and postdoctoral research associate Aleko Khukhunaishvili have implemented new techniques to minimize systematic uncertainties inherent in this measurement and improve its precision.
Understanding the weak mixing angle sheds light on how different forces in the universe work together on the smallest scales. This increases understanding of the fundamental nature of matter and energy.
“The Rochester team has been developing innovative techniques since 2010 and measuring these electroweak parameters and then implementing them in the Large Hadron Collider,” says Bodek. “These new techniques have ushered in a new era of precision testing of the Standard Model predictions.”