Hadron Physics: a World of Colour

Confinement

Exploring the workings of the strong force

The large variety of experimental results on matter under extreme matter conditions, obtained in accelerators on Earth, or on cosmic furnaces, require still significant theoretical understanding.

Most of the visible matter in the Cosmos is made of hadrons.The underlying theory for the behavior of hadrons is Quantum Chromodynamics (QCD). QCD is the theory of the so-called strong force, that binds together quarks, and effectively, nucleons in the nucleus of the atoms. The carriers of this interaction are known as gluons. 

In the very large momentum or very small distance regime, QCD has the property of asymptotic freedom. But for small momentum, or distances at the scale of an hadron (1fm= 10-15 m) confinement of quarks sets in. Gluons can interact with themselves which makes hadrons extremely complex. The confinement of quarks in hadrons is a highly complex problem. 

Intensive QCD numerical simulations of the quarks and gluons in an hadron use a discrete space-time lattice (LQCD) and have made tremendous progress recently. But there are still currently limitations to the description of excited states and decays. Model calculations need to be tested against experimental and lattice data.

The mistery of the formation of heavy quarkonia  and their decays is one of the open questions in Hadron Physics. Other open questions are the origin of the spin of the proton, the identification of exotic (hadrons that are not systems made of 3 or 2 quark/antiquarks) and hybrid hadrons (hadrons which have decays that are not explained within the quark models only). This is a hot topic with a special Highlight from the APS.

We will explore new techniques in our studies, specially the link of LQCD to models and the consequences of chiral symmmetry.  

 

© Hadron Physics 2014