Project B: Search for glueballs in charmonia decays

Project leader: Prof. Dr. Ulrich Wiedner

The goal of this project is to search for glueballs in decays of charmonium resonances at the BESIII experiment. The systematic study of the production, decay and other properties of resonances will allow for the identification of Glueballs over conventional quark-antiquark states and other QCD bound states. The comparison of the production in gluon-rich charmonium decays (this project) and in two-photon interactions (research project F.-H. Heinsius) is of particular interest. This project is focusing on (but is not limited to) processes which have been limited in the past by statistics.

During the first phase in the first three years we studied decays of the P wave charmonium states χcJ and the J∕ψ vector state. In the beginning of the second phase it is planned to finalize the related studies, which have been described above. Also our program will be systematically extended and enhanced by searching for the first time for the vector glueball in electron-position annihilations. The state is predicted at about 3.8 GeV∕c2, substantially heavier than the states which have been addressed up to now by this project. We will also investigate decays of the spin singlet state hc into light hadrons, were odd C parity of the initial state gives access to resonances with quantum numbers different than the ones accessible in χcJ decays.

The data analysis will be organized in a coordinated way with the other groups of the Forschergruppe. In particular the results will be compared to the resonances couplings in two-photon interactions extracted by the group of F.-H. Heinsius. The properties of vector resonances around 3.8 GeV∕c2 will be confronted with the ones of charmonium-like states studied by the research projects of K. Peters and M. Fritsch, respectively. Active collaboration is also envisaged with the research project of A. Khoukaz. One of the goals of the group is the investigation baryon anti-baryon production above the open charm threshold. There is overlap in the relevant final states and experimental methods (partial wave analysis) between the groups, but different energy regimes will be investigated. This will yield complementary information for the identification of resonances.