Over 13,500 researchers who have engaged in experiments at the Large Hadron Collider (LHC), situated in Geneva, Switzerland, have received the 2025 Breakthrough Prize in Fundamental Physics for “evaluating the contemporary theory of particle physics—the Standard Model—and alternative theories describing phenomena that may exist beyond it with high accuracy,” per the website of the foundation. Among the awardees are various Caltech researchers forming part of the team behind the Compact Muon Solenoid (CMS) experiment, one of the four major experiments at the LHC, which is operated by the European Organization for Nuclear Research, commonly known as CERN.
The LHC propels protons around a circular track at nearly light speed. As the protons soar towards one another, a minuscule percentage collide, resulting in the creation of new particles. In 2012, a collaborative effort from an international team of scientists and engineers, including a significant number from the Caltech CMS team, led by Professor of Physics Harvey Newman and Shang-Yi Ch’en Professor of Physics Maria Spiropulu, declared that they had utilized the LHC to identify the long-sought Higgs boson, the essential particle that grants mass to elementary particles. This finding, which validated the final incomplete aspect of the Standard Model of particle physics, later earned Peter Higgs and François Englert the 2013 Nobel Prize in Physics for their theoretical work anticipating the Higgs boson.
“This is an astonishing and exhilarating time,” remarked Spiropulu in a 2012 Caltech news article about the discovery. “Even these preliminary outcomes provide us with crucial insights into how mass in the universe originated. Along with hundreds of our peers, Caltech researchers have labored for years to achieve this milestone: developing successive generations of experiments; designing and constructing detectors that accurately measure photons, electrons, and muons, which are vital to the discovery; and innovating global systems that enable thousands of physicists worldwide to collaborate around the clock, share and analyze data, and create new methodologies leading to this remarkable outcome.”
The Caltech team was among the initial factions in the U.S. to affiliate with CMS at CERN in 1994, according to Newman. In a Caltech article commemorating the 10th anniversary of the achievement, he referred to the discovery as “a significant milestone in human history” that “has irrevocably altered our perspective of the universe.”
Commenting on the recent Breakthrough Prize accolade, Newman expresses that it “has been a privilege to participate in CMS over the last thirty years and to witness our group at Caltech, including numerous graduate students and many undergraduates, innovate, create, or enhance many crucial components and develop novel methodologies leading to the Higgs boson and other findings.”
“From crystal detectors performing with accuracy in the challenging LHC environment to innovative machine-learning/artificial-intelligence approaches to isolate emerging signals from otherwise overwhelming backgrounds to a new category of systems with integrated intelligence that allows us to share and analyze data at global locations, and beyond, we have consistently pushed new boundaries,” he states.
Alongside the Higgs boson discovery and related investigations clarifying how the Higgs field generates mass, the Breakthrough Prize announcement highlights other contributions from the LHC, including “investigating exceedingly rare particle interactions, and exotic states of matter that existed in the universe’s infancy; discovering more than 72 new hadrons and identifying subtle variations between matter and antimatter particles; and establishing robust constraints on possibilities for novel physics beyond the Standard Model, encompassing dark matter, supersymmetry, and concealed extra dimensions.”
The foundation indicated that, after conferring with leaders of the LHC experiments, it will allocate the prize funds, totaling $3 million, to the CERN & Society Foundation. This funding will afford grants for doctoral students from member institutes to devote research time at CERN and provide “students with firsthand experience at the forefront of science and new expertise to take back to their home regions and countries,” as stated by the foundation.
The Caltech CMS team is actively pursuing next-generation detector technology for the High-Luminosity LHC, which is anticipated to commence data collection in 2030.
“Numerous undergraduates at Caltech have contributed to the LHC research initiative at CMS, engaging in tasks related to physics data analysis, instrumentation, and computing,” says Spiropulu. “This work continues with the High-Luminosity LHC, for which Caltech has been pioneering, since 2012, the picosecond-timing ultra-precise novel detector modification to the CMS experiment.”
Newman states, “We look forward with great eagerness, along with our colleagues at Caltech and across high-energy physics, astrophysics, and cosmology, to deepen our understanding of the universe and anticipate the next wave of discoveries in the coming years.”
Two Caltech alumni have also been honored with New Horizons in Physics awards from the Breakthrough Prize Foundation, celebrating early-career accomplishments. Jeongwan Haah (PhD ’13) received recognition in the domain of quantum information “for the discovery of Haah’s code, wherein fractal conservation laws emerge, alongside other models introducing discrete mathematical structures to physics,” and Rebecca Hensen-Clem (PhD ’17) was acknowledged along with two other scientists, in the realm of astronomy “for demonstrating new extreme adaptive optics techniques that will facilitate the direct detection of the tiniest exoplanets.”