Ciclo de Colóquios

Data / Hora
04/12/2018
16:00

Localização
Sala de seminários João Salim Miguel – 3144 – bloco F – 3º andar.
Rio de Janeiro, RJ

Abstract: The strong force is one of the fundamental forces in nature. At distances smaller that the
typical length of the atomic nucleus, the strong nuclear force is much stronger than the
electromagnetic force. For this reason, protons remain bound together in the nucleus even though
they should repel each other. In the last century, lot of other particles that also feel the strong force
have been found, they are called Hadrons. The microscopic theory of the strong interaction between
hadrons is called Quantum Chromodynamics (QCD). However, QCD is not described in terms of
protons or neutrons (or any other hadron), it is described in terms of quarks and gluons, that are
fundamental particles in the Standard Model. Quarks and gluons are special particles as they do not
appear isolated in nature, they always appear forming bound states. Moreover, quark and gluons have
another property called, the color, which gives the name to the theory. In 1973, QCD was shown to be
asymptotically free, and therefore quarks and gluons behave as free particles at large energy.
However, in the opposite regime, the coupling constant between them seems to diverge, for this
reason, this region is usually called the non-perturbative regime. In the last decade, lattice simulations
have found a coupling constant that does not diverge and in fact, is relatively small. Therefore, I am
going to show you that some features of low energy QCD can be understood using that the coupling
constant is small in this regime.