Over the last decades a revolution has occurred in hadron physics: States have been unambiguously experimentally identified with a quark structure beyond that of the common quark models: Mesons, usually thought to consist of a quark-antiquark combination, which have a minimum 4-quark structure (2 quarks and 2 anti-quarks), and baryons, normally built from 3 quarks, which must consist of 5 quarks. Such states have for example, been found at Belle, BESIII and LHCb in the charm quark sector. Similar states seem to exist with strange quarks and have been investigated at Jefferson Lab in USA and ELSA at the University of Bonn. It remains open as to whether these tetra- or pentaquark systems are compact objects subject to colour binding through gluon exchange or, in contrast, molecular-type structures are formed where two ordinary mesons or a meson and a baryon as colour neutral objects bind together through forces similar to atomic nuclei.
In this seminar key papers of both experimental findings and theoretical concepts and interpretations shall be discussed. The idea is that students study one of theses papers and present it to the full audience in a 30 – 40 minute talk. Support during the preparation of the talks will be provided by experienced tutors. 4 cp will be awarded for successful presentations and active participation.
To set the stage, in the first seminar the lecturers will introduce the research context and the papers to be looked into. Assigning talks to interested students shall be started and finalised within two weeks, and the seminar will begin approximately one month later to ensure students have the required time to prepare their presentations.