My name is Andrzej Kupsc and I am the spokesperson of the MesonNet network within HadronPhysics3 project.

I am closely connected with four countries: Poland, Sweden, Germany and Italy. Every year I am spending more than one month in each of the countries. I am Polish but I live in Sweden. I work at Uppsala University. I have still close  connections to my former institute in Poland. I travel frequently to Germany and Italy to carry out experiments on meson decays.

What are the scientifically exciting aspects of your research project?

MesonNet is a network of scientists who investigate subatomic particles called mesons. Let me briefly explain what those objects are. We know that quarks are fundamental constituents of matter, but that they have never been found in isolation. The ordinary matter is built of the lightest quarks called 'up' (u) and 'down' (d) (but there are heavier quarks which physicists successively named 'strange', 'charm', 'bottom' and 'top'). For example, the proton and neutron (the building blocks of the atomic nuclei) contain these light quarks. However, the simplest objects built of quarks which one can observe in an experiment are mesons, particles composed of one quark and one quark-antiparticle (antiquark). An antiparticle has the same mass and the same properties as the corresponding particle, but opposite charge(s). When a particle and its antiparticle meet, they can disappear (annihilate) under the emission of photons which preserve the original energy.

In our network we focus on mesons which are composed of quark-antiquark pairs of the same kind, i.e. up and anti-up, down and anti-down or strange and anti-strange. Such mesons are electrically neutral  are named by Greek letters as  p0, h,  r0, w, f, h'.

Mesons are unstable particles which will decay. However, bearing in mind that they are built of quark-antiquark pairs, it is amazing that some of them live million times longer than naively expected from the collision of a particle with its own antiparticle.

We study the properties of these mesons by investigating the mechanism(s) how they are produced and by making precise observations on how they decay at different accelerator laboratories in Europe.

MesonNet is a network characterized by a broad range of interests of the participating scientists and it is difficult to mention all exciting subject which we investigate. Therefore, I will focus on  two examples which are especially appealing to me personally.

Some of the mesons have very low masses. In fact, it can be shown that the  p0  meson would be massless if the quarks themselves were massless. For a proof of this fact, Nambu was awarded the Nobel Prize in physics in 2008. It appears that some of the decays of the h meson provide the most sensitive source of information on the up and down quark masses.  Within the MesonNet several experiments aim for determination of these masses using this approach.

The second example relates to tests of the fundamental symmetries of Nature. When the quark and antiquark constituents of a p0  meson annihilate, exactly two photons are emitted. If one would be able to observe a decay event with three photons, this would be a direct proof of a tiny asymmetry between matter and antimatter in electromagnetic interactions.

Who is participating in MesonNet?

Experimentalist carrying out research at  European laboratories: LNF Frascati,  Mainz,  Bonn, GSI Darmstad and  FZ Jülich and theory groups across Europe.

What do you want to achieve with this activity?

- To bring together experimentalist at different facilities and theorist in order to create new ideas.

- Try to attract new students to our research field.

In general, why do you think should a young person choose to study science and why should they do so in Europe?

I can only speak for myself, why I have selected science in the first place. When I started secondary school, I was already sure what I would do in the future. I should be an engineer: an aircraft constructor. It was the first physics lesson that completely changed my direction and ultimately lead to that I became a physicist. We had a passionate teacher who just started her first job after graduation. There was one statement that blew our minds: "Physicist are searching for a formula to describe all laws of the Universe". Actually from our class three persons ended up being physicists.

I can only assure that science is fun and there is a great intellectual pleasure  when  you get to understand how things work.

Would you like to add anything?

Year 2011 was celebrated as Marie Skłodowska Curie Year in Poland. She was two times Nobel Prize laureate, the only science Nobel Prize winner from Poland so far.  Actually all my supervisors when working in Poland were women.

The HadronPhysics3 project is supported by the European Union
under the 7th Framework Capacities Programme in the area of Research Infrastructures (RI).