Bochum 2009 – wissenschaftliches Programm
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HK: Fachverband Hadronen und Kerne
HK 12: Heavy Ion Collisions and QCD phases
HK 12.6: Vortrag
Montag, 16. März 2009, 18:15–18:30, H-ZO 10
Role of the tetraquark in the chiral phase transition — •Achim Heinz1, Stefan Strüber1, Francesco Giacosa1, and Dirk H. Rischke1,2 — 1Institute for Theoretical Physics, Geothe University, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main, Germany — 2Frankfurt Institute for Advanced Studies, Geothe University, Ruth-Moufang-Str. 1, D-60438 Frankfurt am Main, Germany
By using a simple chiral invariant two-flavor model, we determine the implication of a light tetraquark field on chiral symmetry restoration at nonzero temperature. The order of phase transition depends on the mixing between quarkonium and tetraquark. In order to obtain a crossover phase transition, as favored by lattice QCD studies, a large mixing between scalar quarkonium and tetraquark fields is required. To be consistent with recently advocated interpretations of spectroscopy data we chose a light (∼ 0.4 GeV), predominantly tetraquark state, and a heavy (∼ 1.2 GeV), predominantly quarkonium state in the vacuum. With increasing temperature the mixing increases until a interchange of roles takes place. The originally heavy, predominantly quarkonium state becomes the light state and the originally light, predominantly tetraquark state becomes the heavy state. After the interchange, as expected, the chiral symmetry is restored.