Session E5: Charm

Charm Spectroscopy.

Recent experimental results in charm spectroscopy are discussed. During the last few years many new $D$, $D_s$, charmonium, and charmed baryon excited states have been discovered. Some of these states were not expected theoretically; their masses, widths, quantum numbers, and decay modes did not fit the existing spectroscopic classification, which was based mostly on potential model calculations. The theoretical models have been improved and new approaches have been developed to explain the data; the possibility of a non-quark-antiquark interpretation of these states has also been widely discussed. To begin, a short overview of theoretical models used to describe charm spectroscopy will be presented. Then, recent results on excited $D$ and $D_s$ meson production will be reported. The specific behaviour of the $D_{sJ}$ mesons will be discussed. A significant part of this talk will be devoted to charmonium spectroscopy. Although the nature of the newly discovered charmonium resonances is not yet fully understood, the $X(3872)$ and $Y(4260)$ resonances are interpreted as molecular or hybrid states in most theoretical papers. If this interpretation is confirmed by future measurements, it will have a revolutionary impact on particle physics. In the last part of the talk recent results in charm baryon spectroscopy will be reported.   

D0-D0bar Mixing

I will present a brief introduction to charm mixing formalism. I will then summarize the current measurements of mixing parameters from various experiments, particularly BaBar, Belle and CLEO-c, and will compare the results with the theoretical predictions.   

Charm Decays

I will review recent charm decay measurements from collider and fixed target experiments, with emphasis on their role in the indirect search for new physics in the flavor sector. Precision measurements of leptonic, semileptonic and hadronic charm decays improve the constraints on the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix, both directly through measurements of the CKM matrix elements $|V_{cd}|$ and $|V_{cs}|$ and indirectly by measuring strong interaction effects that illuminate the interpretation of CKM measurements in the b-quark sector. Rare charm decays also provide indirect constraints on new physics.