Sonderseminar Marc Pelizäus (Universität Bochum)

Exotic Hadrons in Electron-Positron and Antiproton-Proton Annihilations

Abstract:

In the Standard Model of Particle Physics protons and neutrons, which are forming the matter surrounding us, as well as other hadrons are bound states of quarks. Quantum Chromodynamics (QCD) is commonly accepted to be the underlying theory of the strong interaction between the quarks, which is well understood at high energies. In the low energy regime, where hadronic bound states are formed, QCD becomes a strongly coupled theory. In this regime fundamental questions remain open: Why are quarks confined into hadrons? Where do hadrons, including protons and neutrons, exactly gain their masses from? Do exotic hadrons exist?

These questions can be addressed by hadron spectroscopy, the systematic study of hadrons and their properties. Of particular interest is the energy region of the heavy charm quark as it probes the transition region between perturbative and non-perturbative QCD.

Surprising discoveries at the B factories started in 2003 with the observation of the enigmatic Ds0*(2317) in the open charm and the X(3872) in the charmonium sector. This has led to a chain of consecutive discoveries of new and often unexplained states which continues until today. The charged charmonium-like Zc states may most evidently signal the existence of exotic multiquark states. The basic properties of QCD also suggest the existence of glueballs, bound states solely consisting of gluons, which still have to be identified unambiguously.

Key player experiments in the field are the BES III experiment which has collected large data samples in electron-positron annihilations in the tau-charm mass region and in future the PANDA antiproton experiment at FAIR. Recent achievements of BES III to understand exotic hadrons and future prospects for BES III and PANDA will be discussed.

 

Hörsaal HISKP, Raum 0.023

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