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Welcome to the Research Group of Tetyana Galatyuk

Members of the ViP-QM group on December 6th 2019.
Members of the ViP-QM group on December 6th 2019.

News from the Group

  • 2021/09/06

    Niklas Schild has successfully finished his Master's thesis

    Niklas Schild has finished his Master's thesis titled “System size and centrality dependence of thermal radiation measured by HADES”. We wholeheartedly congratulate Niklas on his graduation.

  • 2021/07/26

    Frederic Kornas has successfully defended his PhD Thesis

    Frederic Kornas has successfully defended his PhD Thesis titled “Global polarization of Lambda hyperons as a probe for vortical effects in Au+Au collisions at HADES”. We wholeheartedly congratulate Frederic!

  • 2020/07/01

    Adrian Rost has successfully defended his PhD Thesis

    Adrian Rost has successfully defended his PhD Thesis titled “Design, installation and commissioning of new read-out electronics for HADES ECAL and diamond detectors for T0-reconstruction and beam diagnostics”. We wholeheartedly congratulate Adrian!

ViP-QM – Exploring the QCD-Medium with electromagnetic probes

Exploring cosmic states of matter …

Sketch of the phase diagram of strongly interacting (QCD) matter.
Sketch of the phase diagram of strongly interacting (QCD) matter.

What happens when gold nuclei, accelerated to about 90% of the speed of light, strike gold nuclei at rest?

For an extremely short time, t ~ 10-23 seconds, states of matter at extreme temperatures (>1012 K) and densities (>280 Mt/cm3) are produced. The possibility to form and explore in the laboratory strongly interacting matter under conditions similar to those realized a few microseconds after the ”Big Bang”, or still existing today in the interior of compact stellar objects is truly fascinating.

The physics to understand their properties touches most fundamental aspects of nature, namely the formation of matter out of nearly mass-less elementary particles.

During the last decades, substantial effort has been devoted to the study of nuclear matter far from its ground state. The goal of this endeavour is to explore the phase structures of strong-interaction matter, which is governed by the laws of Quantum Chromo Dynamics (QCD), by creating extreme states of matter in the laboratory. The phase diagram of QCD matter, indicating the conjectured phase boundaries in a graph correlating temperature (T) and baryochemical potential (µB), is shown in Figure 1. In the very early Universe the matter was balanced by antimatter and thus characterised by vanishing baryochemical potential (µB = 0) and high temperatures. Compact stellar objects like neutron stars, on the other hand, have comparatively small temperatures and large baryochemical potential.

… with virtual photons …

Photons, since long, have been a very successful tool to study properties of “matter“. Just think about the success story of the mysterious electromagnetic radiation discovered by Wilhelm Conrad Roentgen (X-rays). Since 1895 X-rays allow us to look inside the human body.

In 1900 Max Planck described the thermal electromagnetic radiation emitted by a black body, when heated to a high temperature, and could predict how this spectrum would be modified as the temperature was changed.

Virtual photons, the generalized form of electromagnetic radiation, materialize after short time by formation of a pair of charged leptons, e.g. an electron and a positron.

Throughout the course of a heavy-ion collision such photons offer the unique opportunity to directly monitor “Roentgen-images” (in-medium electromagnetic spectral functions) and to measure “Planck-like-spectra” (temperature of the emitting source) of strongly interacting matter.

Electron-positron pairs are radiated throughout the whole time evolution of a heavy-ion collision.
Electron-positron pairs are radiated throughout the whole time evolution of a heavy-ion collision.

Real and virtual photons emitted from the hot and dense collision zone formed in heavy-ion reactions are a unique tool for investigating properties of strong-interaction matter under extreme conditions. Electromagnetic probes (dileptons and photons) carry important information about the decaying objects to the detectors without being affected by strong final-state interaction while traversing the medium. The key objective of using dileptons as probes is to gain insight to the mechanism of dynamical chiral symmetry breaking, changes in the degrees of freedom, and possibly to discover unconventional states of matter.

… in the laboratory

Our group aims at pursuing a dilepton program at the present GSI facility withwith the HADES, at the BNL facility with STAR and at the future FAIR facility with CBM in order to systematically map out how the dilepton signals change across the QCD phase diagram and in this way reflect its structure. The particular focus is put on matter at high net-baryon densities and moderate temperatures.