October 10, 2025
Influential theorist remembered for deep appreciation of experimentalism, commitment to public service within scientific community
Jonathan L. Rosner, a distinguished theoretical physicist and professor emeritus at the University of Chicago, passed away on May 24, 2025. He made profound contributions to particle physics, particularly in quark dynamics and the Standard Model.
Born in New York City, Rosner grew up in Yonkers, NY. He earned his bachelor of arts in physics from Swarthmore College in 1962 and completed his PhD at Princeton University in 1965 with Sam Treiman as his thesis advisor. His early academic appointments included positions at the University of Washington and Tel Aviv University. In 1969 he joined the faculty at the University of Minnesota, where he served until 1982. That year, he became a professor at the University of Chicago, where he remained a central figure in the Enrico Fermi Institute and the Department of Physics until his retirement in 2011.
Rosner’s research spanned a broad spectrum of topics in particle physics, with a focus on the properties and interactions of quarks and leptons in the Standard Model and beyond. “His many papers on a wide range of different topics featured interesting and informed questions about the detailed structure of nature from the smallest to the largest, and a remarkable clarity and comprehensiveness in the answers,” said Henry Frisch, UChicago professor of physics and close, long-time colleague.
In a highly influential paper in 1969, Rosner pointed out that the duality between hadronic s-channel scattering and t-channel exchanges could be understood graphically, in terms of quark worldlines. Approximately three months before the “November revolution,” i.e. the experimental discovery of charm–anticharm particles, together with the late Mary K. Gaillard and Benjamin W. Lee, Rosner published a seminal paper predicting the properties of hadronic states containing charm quarks.
He made significant contributions to the study of mesons and baryons, exploring their spectra and decay processes. His work on quarkonium systems, particularly the charmonium and bottomonium states, provided critical insights into the strong force that binds quarks together. He also made masterful use of algebraic methods in predicting and analyzing CP-violating observables.
In more recent years, Rosner focused on exotic combinations of quarks and antiquarks, tetraquarks and pentaquarks. In 2017 he co-authored a Physical Review Letters paper that provided the first robust prediction of a bbud tetraquark that would be stable under the strong interaction.
What truly set Rosner apart was his rare ability to seamlessly integrate theoretical acumen with practical experimental engagement. While primarily a theoretician, he held a deep appreciation for experimental data and actively participated in the experimental endeavor. A prime example of this was his long-standing involvement with the CLEO collaboration at Cornell University.
He also collaborated on studies related to the detection of cosmic-ray air showers and contributed to the development of prototype systems for detecting radio pulses associated with these high-energy events. His interdisciplinary approach bridged theoretical predictions with experimental observations, enhancing the coherence between theory and practice in high-energy physics.
Unusually for a theorist, Rosner was a high-level expert in electronics, rooted through his deep life-long interest in amateur short-wave radio. As with everything else, he did it very thoroughly, from physics analysis to travelling to solar eclipses to take advantage of the increased propagation range of the electromagnetic waves caused by changes in the ionosphere.
“Jon taught the electronics course for undergraduates and the graduate advanced lab course,” said Frisch, “almost certainly the first and last time a theorist will have taught either one.”
Rosner was also deeply committed to public service within the scientific community. He served as chair of the Division of Particles and Fields of the American Physical Society in 2013, during which he played a central role in organizing the “Snowmass on the Mississippi” conference. This event was an essential part of the long-term strategic planning for the US high-energy physics program. His leadership and vision were widely recognized and appreciated by his peers.
Throughout his career, Rosner received numerous accolades. He was a fellow of the American Physical Society and was awarded fellowships from the Alfred P. Sloan Foundation and the John Simon Guggenheim Memorial Foundation. His publication record includes more than 500 theoretical papers, reflecting his prolific and highly impactful career in physics. He is survived by his wife, Joy, their two children, Hannah and Benjamin, and a granddaughter, Sadie.
Adapted from an obituary written by Marek Karliner (Tel Aviv University) and Fred Gilman (Carnegie Mellon University), originally published by the CERN Courier.