The QCD phase diagram at zero and small baryon density

Abstract

I review recent developments in determining the QCD phase diagram by means of lattice simulations. Since the invention of methods to side-step the sign problem a few years ago, a number of additional variants have been proposed, and progress has been made towards understanding some of the systematics involved. All available techniques agree on the transition temperature as a function of density in the regime μ_q/T < 1. There are by now four calculations with signals for a critical point, two of them at similar parameter values and with consistent results. However, it also emerges that the location of the critical point is exceedingly quark mass sensitive. At the same time sizeable finite volume, cut-off and step size effects have been uncovered, demanding additional investigations with exact algorithms on larger and finer lattices before quantitative conclusions can be drawn. Depending on the sign of these corrections, there is ample room for the eventual phase diagram to look as expected or also quite different, with no critical point at all.

30 pages, plenary talk presented at the XXIIIrd International Symposium on Lattice Field Theory, 25-30 July 2005, Trinity College, Dublin, Ireland

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Cited by in corpus (12)

• The density of states method at non-zero chemical potential
• Finite density QCD with a canonical approach
• Lattice QCD at finite temperature and density
• Fluidity and supercriticality of the QCD matter created in relativistic heavy ion collisions
• QCD phase diagram: an overview
• Towards extremely dense matter on the lattice
• Exploring the QCD phase diagram
• Analytical continuation from imaginary to real chemical potential in 2-color QCD under scrutiny
• Color superconductivity in ultra-dense quark matter
• Lattice QCD at finite density: imaginary chemical potential
• Constraints for the QCD phase diagram from imaginary chemical potential
• Toward the Understanding of Quark Matter Formation