University of Minnesota
School of Physics & Astronomy


International Charm offensive

Ron Poling
Ron Poling
Alex Schumann

In January, 2008 the Minnesota “Heavy Flavor” group led by Professors Ron Poling and Dan Cronin-Hennessy joined the BESIII experiment at the Institute of High Energy Physics in Beijing, China. This expanded an already fruitful program of collaborative research in high energy physics between the United States and the People’s Republic of China that was initiated by T.D. Lee, “Pief” Panofsky and Bob Wilson in the 1970’s.

Minnesota is a long-time contributor to the CLEO experiment at the CESR electron-positron collider, which studied the heavy quarks b (bottom) and c (charm) for three decades. Poling’s career in experimental high energy physics began with the first of more than 200 Ph.D. dissertations that have been completed with CLEO data. It reported the first unmistakable evidence for b quarks, and his subsequent work included first measurements of b decays to charmonium and to charmless final states.

CLEO pioneered the era of high-precision b physics that has included experiments all over the world, at electron-positron colliders (DORIS in Germany, LEP at CERN, KEK-B in Japan, and PEP-II in the U.S.) and at hadron colliders (the Tevatron in the U.S. and soon the LHC at CERN). As the number of b experiments grew and CESR neared completion, CLEO redirected its program to charm. While charm started heavy flavor physics with the “November Revolution” of 1974, it was relatively neglected during the time of intense interest in b physics. Charm plays a crucial role in the Standard Model, however, providing rigorous tests of strong interaction theory, searches for possible signatures of physics beyond the Standard Model, and precision measurement that will help disentangle the complex physics to be studied at the LHC.

The BESIII detector has a very similar design to CLEO, so it was natural for leaders of the U.S. and Chinese high energy physics programs to encourage migration of CLEO physicists to the new experiment. Minnesota led a group of five universities in their move to BESIII and has moved quickly to establish a significant role in the experiment. The group’s initial objective is to build on CLEO expertise and tools to achieve smooth operation and high-precision measurements with the complex BESIII detector faster than would otherwise be possible. Specific software packages have been adapted and a 100-CPU computer cluster here in Minnesota has been redirected from CLEO to BESIII. A major upgrade is being planned to accommodate much larger data samples.

Although they have a lower profile than the LHC, experiments like CLEO and BESIII play important roles in building a comprehensive picture of elementary particles and their interactions. With costs and collaborations that are small compared to major collider projects, these programs offer faculty, postdocs and graduate students unique data samples and opportunities for precision measurements in support of theory and other experiments. These researchers know that exploration of the high-precision frontier, like exploration of the energy frontier, could lead to unexpected discoveries.

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