Description
Prof. Dr. Johanna Stachel (Heidelberg University), "Exploring the phase diagram of strongly interacting matter with collisions of nuclei at the LHC"
The theory of strong interaction, quantum-chromo-dynamics,
predicts for high temperature and density a new state of matter in
which the confinement of quarks and gluons is lifted. This state, the
quark-gluon-plasma, existed in the early universe after the
electro-weak phase transition up to about 10 microseconds. Results
from lattice QCD on the phase diagram will be presented. In the past
35 years accelerator-based experiments have been conducted in order to
recreate this state of matter for a short time. The ideal tool are
collisions of heavy nuclei at energies as high as possible. With the
Large Hadron Collider (LHC) at CERN an entirely new energy regime
became accessible.
Two aspects of the data will be explored: (i) Experimental knowledge
about the phase boundary between ordinary hadronic matter and the
quark-gluon plasma: This is based on the measured yields of various
hadronic species. Here a direct link can be made the the full
statistical operator of QCD including it's fluctuations. (ii)
Evidence for deconfinement: This comes from the production of
charmonia as a function of center of mass energy and centrality of the
collision. The LHC data offer a unique signature.
