QCD phase structure at finite temperature and density
Final Report Abstract
Understanding the properties and possible phases of strongly-interacting matter under extreme conditions is one of the big challenges of high-energy physics. Hot strongly-interacting matter of several 10^12 Kelvin was prevalent in the very early universe and similar conditions can be created by colliding heavy ions in particle accelerators, like lead ions at the Large Hadron Collider (LHC) at CERN, Geneva, and gold ions at the Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Lab (BNL). On the other hand, densities of the same order of magnitude as present in atomic nuclei can be found in neutron stars, and similar densities are investigated in the Beam Energy Scan program at RHIC and the High Acceptance DiElectron Spectrometer (HADES) as well as the planned Facility for Antiproton and Ion Research (FAIR) of the Gesellschaft fur Schwerionenforschung in Darmstadt. Stronglyinteracting matter is described by Quantum Chromodynamics (QCD) and its behaviour as a function of temperature and density is sum- marised in the QCD phase diagram. Although much progress has been made in the last decades, the properties of strongly-interacting matter at intermediate and high densities are still not calculable from first principles. The main objective of this project was a model-parameter free investigation of the phase diagram of QCD. Despite the early termination of the project, important progress towards this goal has been made and crucial insights about the necessary prerequisites for such an investigation have been found. The most important finding during the time of this project was the surprising sensitivity of approximation schemes for the used functional renormalization group equation to comparably small violations of a crucial symmetry of the underlying theory, namely BRST symmetry. Although there exists still no general strategy for devising consistent approximation schemes, important insights on their required properties could be found, laying the foundation for subsequent first-principles investigations of the QCD phase structure and the calculation of related phenomenologically important observables with the functional renormalization group equation.
Publications
- Bound state properties from the Functional Renormalisation Group
R. Alkofer, A. Maas, W. A. Mian, M. Mitter, J. Paris-López, J. M. Pawlowski, N. Wink
(See online at https://doi.org/10.1103/PhysRevD.99.054029) - Dynamical generation of low-energy couplings from quarkmeson fluctuations
F. Divotgey, J. Eser, M. Mitter
(See online at https://doi.org/10.1103/PhysRevD.99.054023) - Correlation functions of three-dimensional Yang-Mills theory from the FRG. SciPost Phys. 5 (2018) 066
Lukas Corell, Anton K. Cyrol, Mario Mitter, Jan M. Pawlowski, Nils Strodthoff
(See online at https://doi.org/10.21468/SciPostPhys.5.6.066) - Low-energy limit of the O(4) quark-meson model from the functional renormalization group approach. Phys.Rev. D98 (2018) no.1, 014024
Jürgen Eser, Florian Divotgey, Mario Mitter, Dirk H. Rischke
(See online at https://doi.org/10.1103/PhysRevD.98.014024) - Nonperturbative quark, gluon, and meson correlators of unquenched QCD. Phys.Rev. D97 (2018) no.5, 054006
Anton K. Cyrol, Mario Mitter, Jan M. Pawlowski, Nils Strodthoff
(See online at https://doi.org/10.1103/PhysRevD.97.054006) - Nonperturbative finite-temperature Yang-Mills theory. Phys.Rev. D97 (2018) no.5, 054015
Anton K. Cyrol, Mario Mitter, Jan M. Pawlowski, Nils Strodthoff
(See online at https://doi.org/10.1103/PhysRevD.97.054015)
