Ulrich Baur, a professor in the University at Buffalo Department of Physics, died Nov. 25 while on vacation with his wife, Yvonne, in the U.S. Virgin Islands. He was 53.
Baur, a native of Munich, where he will be buried, was an important figure in theoretical high-energy physics. His calculations for the Large Hadron Collider have laid the groundwork for many measurements being conducted there and have become increasingly essential for interpreting the new data they are generating.
The LHC experiments are designed to identify signs of new physics that will challenge the Standard Model, the prevailing understanding of the behavior of subatomic particles.
“Ulrich’s calculations are essential for understanding the interactions between fundamental particles at very high energies” says colleague Doreen Wackeroth, PhD, associate professor of physics at UB. “He developed new ideas to test our understanding of the weak nuclear force and how to measure the properties of the top quark (the heaviest fundamental particle) and the elusive Higgs particle, once it is discovered. We are very eager to see how much the new LHC data will reflect this.”
According to Wackeroth, Baur was working very hard to interpret the LHC data on the theoretical side and to look for discrepancies between the data and the Standard Model, which would provide signals of new physics.
“He was so active, he had so many ideas and he was in the middle of it,” says Wackeroth. “It is a huge loss, both on a personal level and also for the entire international physics community.”
Baur was also unique in that he was skilled, his colleagues say, at bridging the often disparate worlds of the theoretical physicists and the experimentalists.
“You need people like Ulrich who can talk in both languages,” says Wackeroth. “He was unique in that sense.”
Hong Luo, chair of the UB Department of Physics in the College of Arts and Sciences, credits Baur with building the entire high-energy physics and cosmology group at UB.
“When he came here, we didn’t have a strong high-energy group and no cosmology group. But now we have a very good group and Ulrich was the driving force behind all of this,” says Luo. “He demonstrated real leadership and his colleagues have tremendous respect for him.”
Baur and Luo also worked together to improve the way the introductory physics courses are taught to undergraduates by introducing team-teaching and increasing interaction between students and faculty.
Baur is known among physicists for his landmark calculations of processes involving subatomic particles, such as Higgs bosons and top quarks and for studying minute quantum effects in the production of the W and Z bosons (the mediators of the weak force) at high energy particle accelerators.
He was named a Fellow of the American Physical Society in 2008 in recognition of his contributions to precision electroweak physics, especially the precision study of W and Z bosons at Fermilab and the LHC, which is a unique way of testing the quantum nature of fundamental particle interactions.
Baur was a member of the LHC Compact Muon Solenoid (CMS) collaboration, and served as co-convener of working groups and co-organizer of numerous workshops, including the annual LoopFest series, now in its ninth year, on current and future high-energy physics programs at Fermilab, the LHC and the International Linear Collider (ILC).
His research had been funded continuously since 1996 by the National Science Foundation, and he co-authored more than 100 scientific papers.
He was one of the founders of the LHC Theory Initiative, designed to encourage graduate study in theoretical particle physics and to address what Baur had called the “outsourcing” of theoretical physics research to countries other than the U.S. Those efforts paid off in 2007 with the establishment by the National Science Foundation of the Large Hadron Collider Theory Initiative, which provided funding for U.S. graduate students who pursue LHC-related research.
Baur obtained his PhD in 1985 working with Harald Fritzsch on phenomenological aspects of composite models at Ludwig Maximilian University in Munich, Germany. He joined the UB faculty after holding a postdoctoral position at the Max-Planck Institute for Physics and Astrophysics in Munich, and serving as a Max-Kade Fellow at Fermilab, a Research Fellow at CERN, a Superconducting Supercollider National Fellow, a visiting assistant professor at the University of Wisconsin and a senior research scientist at the University of Florida.
Guido Tonelli, the CMS spokesperson-elect, says that Baur “will always be remembered by his colleagues for his cheerful humor, his enthusiasm and dedication to physics, and for his encouragement of younger physicists. He will be sorely missed.”
A funeral service will be held Dec. 17 in Munich. A symposium to honor Baur’s contributions to theoretical high-energy physics is planned for spring 2011.
