University of Pennsylvania
Department of Physics and Astronomy
High Energy Physics Seminar

The first meson, a strongly interacting particle predicted by Yukawa in 1935, was discovered in mountaintop cosmic ray experiments reported in 1947. Just over fifty years later, physicists in the CDF collaboration have discovered the last meson in high energy proton-antiproton collisions at the Fermilab Tevatron. Mesons are composite particles, containing a quark and an antiquark. There are just fifteen such combinations. They constitute a kind of periodic table of mesons, each having a rich spectrum of excited states. With the the discovery of the B_c, a combination of a charmed quark and a bottom antiquark, the table is now complete. I shall discuss the theoretical predictions for the properties of this particle, why some refer to it as "the hydrogen atom" of Quantum ChromoDynamics, how we identified it, and how we measured some of its properties.