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Welcome to the Research Group of Tetyana Galatyuk

ViP-QM group picture
Members of the ViP-QM group on December 16th 2014.

Helmholtz Young Investigator Group:

ViP-QM – Exploring Quark Matter with Virtual Photons

Exploring cosmic states of matter …

phase diagram of stronglty interacting 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.

… 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.

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

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.

This is the aim of the ViP-QM “Exploring Quark Matter with Virtual Photons” Helmholtz-YIG.

… in the laboratory

The ultimate goal of this research is to provide a complete excitation function of dilepton production for heavy-ion collisions ranging from 1 GeV per nucleon up to energies of 11 GeV per nucleon, i.e. top energies provided by SIS18 at GSI to later top energies provided by SIS100 at FAIR, with the HADES and CBM experiments.

We systematically extract the so-called excess spectra of dileptons and analyze them such as to extract from their spectral properties the (initial) temperatures of the system and from the amount of radiation its lifetime. These excitation functions will serve as an observable to search for a first-order Quantum Chromo Dynamics (QCD) phase transition from nuclear to the nearly mass-less quark matter, by hunting for a non-monotonous behavior of the temperature and lifetime showing evidence of a latent heat.