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HK: Fachverband Physik der Hadronen und Kerne

HK 14: Theorie

HK 14.5: Vortrag

Dienstag, 13. März 2007, 15:15–15:30, C

Modeling the QCD-phase diagram in and beyond mean field theory — •Simon Rößner¹, Thomas Hell¹, Claudia Ratti², and Wolfram Weise¹ — ¹Physik Department, TU München, 85747 Garching, Germany — ²ECT*, I-38050 Villazzano (Trento), Italy

The two most prominent non-perturbative effects in QCD, spontaneous chiral symmetry breaking and confinement, are the major driving forces of QCD dynamics at energies below 1 GeV. The PNJL model incorporating these features [1,2] shows astonishingly good agreement with full QCD calculations [3]. We present predictions on the QCD phase diagram derived within the framework of this model. The critical point with its current quark mass dependence will be studied as well as the speed of sound [4].

So far the calculation in the PNJL-model have been performed using a mean field approximation. This approach does not allow for a proper treatment of fermion sign problem, which appears on equal footing in QCD. The ansatz we would like to present provides systematic corrections to the mean field approximation. The lowest order corrections lead to a split of the thermal expectation value of Polyakov loop and its complex conjugate. It can be seen from this ansatz that this split is caused by fluctuations and is not part of the mean field result.

Work supported in part by BMBF and GSI.

[1] C. Ratti, M. A. Thaler, W. Weise, Phys. Rev. D73, 014019 (2006).

[2] C. Ratti et al., to appear in Eur. Phys. J. C [arXiv:hep-ph/0609218].

[3] C. R. Allton et al., Phys. Rev. D71, 054508 (2005).

[4] S. Rößner, C. Ratti and W. Weise, [arXiv:hep-ph/0609281].