Symmetries and in-medium effects: Chiral symmetry breaking and modification of meson properties in a strongly interacting medium
1 II. Physikalisches Institut, Universität Giessen Heinrich-Buff-Ring 16, 35392 Giessen, Germany
2 Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, Nußallee 14-16, 53115 Bonn, Germany
Published online: 25 September 2014
Chiral symmetry is a fundamental symmetry of Quantum Chromodynamics (QCD) in the limit of vanishing quark masses. In the hadronic sector chiral symmetry is broken; otherwise chiral partners - hadronic states with the same spin but opposite parity - should be degenerate in mass which is not observed in nature. It has been suggested that chiral symmetry might at least be partially restored in a strongly interacting environment. As a consequence, properties of hadrons, encoded in their mass and width, may be modified when embedded in a nucleus. These ideas have motivated widespread theoretical and experimental activities. As an example, recent experimental results on the in-medium properties of the η′ meson are presented.
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