Nuclear and particle physics:

Nick van Eijndhoven (Brussels) (25+5min)

Deep Space Observed through an Antarctic Ice Box

Astroparticle Physics revolves around phenomena that involve (astro)physics under the most extreme conditions. Cosmic explosions, involving black holes with masses a billion times greater than the mass of the Sun, accelerate particles to velocities close to the speed of light and display a variety of relativistic effects.
The produced high-energy particles may be detected on Earth and as such
can provide us insight in the physical processes underlying these cataclysmic events. Having no electrical charge and interacting only weakly with matter, neutrinos are special astronomical messengers. Only they can carry information from violent cosmological events at the edge of the observable universe directly towards the Earth. 

At the Inter-university Institute for High Energies (IIHE) in Brussels we are involved in a world wide effort to search for high-energy neutrinos originating from cosmic phenomena. For this we use the IceCube neutrino observatory at the South Pole, the world's largest neutrino telescope which is now nearly completed (i.e. 79 out of 86 strings deployed) and taking data.

One of the research areas at the IIHE comprises studies of transient phenomena,
i.e. Gamma Ray Bursts (GRBs) and flares of Active Galactic Nuclei (AGN), which
are believed to be the most violent cosmic explosions involving black holes and
neutron stars.

In this talk I will present the underlying ideas of high-energy neutrino production in explosive cosmic phenomena and the IceCube detection principles. It will be shown how the combination of IceCube data with satellite observations opens up the possibility of identifying high-energy neutrinos originating from transient cosmic events for the first time in history.

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Harm Schoorlemmer (Nijmegen) (15+5min)

Radio detection of cosmic rays at the Pierre Auger Observatory

The detection of radio emission from cosmic ray induced air showers is 
taking place at the Pierre Auger Observatory in Malargüe Argentina. 
Several setups are taking data, and are used as a test base for AERA, 
the 20 km^=2 radio detection extension of the Pierre Auger Observatory.
Measurements obtained with one of these initial setups provide promising 
data to study background sources and emission mechanisms. In this talk 
physics results of this setup up are discussed.

*****************************************************************Raimond Snellings (Amsterdam) (25+5min)

The Quark Gluon Plasma

One of the fundamental questions in the field of subatomic physics is: What are the properties of matter at extreme densities and temperatures? This matter may have existed in the first microseconds after the big bang and currently exist, perhaps, in the core of dense neutron stars. We try to recreate and study such a state of matter, the so called Quark Gluon Plasma, in the laboratory by colliding heavy-ions at very high energies. I will briefly review our current understanding of this state of matter and focus on what we expect to learn from heavy-ion collisions at the Large Hadron Collider (LHC) observed in the ALICE apparatus.

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David Dudal (U Gent) (15+5min)

Yang-Mills theory in the Landau gauge

We take a look at SU(N) Yang-Mills gauge theories which are quantized in
the Landau gauge. This is a popular study object, as this particular gauge can also be implemented numerically, hence one can look at nonperturbative features of gauge fixed theories using lattice simulations.

A great deal of attention is paid to the propagators of the elementary fields (gluon and ghost). Although not physical themselves, they are the basic building blocks for more involved analyses. In the ultraviolet, perturbation theory works fine. In the infrared region, things change drastically, and nonperturbative tools are in order.

A specific source of nonperturbative infrared effects might be caused by gauge (Gribov) copies. We present a short summary of the Gribov-Zwanziger approach to treat this problem, and how this framework is able to describe the lattice data, qualitatively and quantitatively.

To understand the consequences at the physical level, one needs to go beyond the elementary propagators and look at correlators of gauge invariant operators, which describe glueballs. We spend a few words on this difficult problem and ongoing research.

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O.O. Versolato (Groningen) (15+5min)

Atomic Parity Violation - Measuring the Weinberg Angle at Low Energies

Atomic parity violation (APV) experiments are sensitive probes of the electroweak interaction at low energy. For instance, the most stringent limit on the mass of an additional heavy Z'-boson can be extracted from the state-of-the-art Cs APV experiment. APV arises from the exchange of the Z0 boson between the electrons and the quarks in the atomic nucleus. Its size depends on the mixing angle of the photon and the Z0$ boson, which is a fundamental parameter of the electroweak
theory (Weinberg angle). The APV signal is strongly enhanced in heavy atoms and it is measurable by exciting suppressed (M1, E2) transitions.
In this talk, the status of APV experiments and theory are reviewed. In particular, the prospects of an APV experiment using one single trapped Ra+ ion are discussed. The predicted enhancement factor of the APV effect in Ra+ is about 50 times larger than in Cs atoms. However, spectroscopic information on Ra+ needed to constrain the required atomic many-body theory, is lacking. Using the AGOR cyclotron and the TRIµP facility at KVI in Groningen, short-lived 212-214 Ra+ ions were produced and trapped.
Excited-state laser spectroscopy was performed on the trapped ions. These measurements provide a benchmark for atomic theory which is required to extract the electroweak mixing angle to sub-1% accuracy and are an important step towards an APV experiment in a single trapped Ra+ ion.