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Seminário do Grupo de Física Teórica

Título: From gluons to glueballs in the Landau gauge

Resumo: In recent years, almost exact lattice results become available for the gluon and ghost propagator in the Landau gauge. We give a short overview of how to accommodate these lattice results in terms of the Gribov-Zwanziger theory, which is an improvement of the perturbative Faddeev-Popov gauge fixing construction, in particular the existence of gauge (Gribov) copies is taken into proper account. We outline the importance of d=2 condensates in order to match analytical & numerical results. This brings us to the Refined Gribov-Zwanziger theory (RGZ). It then turns out that the gluon cannot be a physical excitation, due to a clear violation of positivity. This is interpreted as a manifestation of confinement. The big question lying ahead is how to convert the unphysical gluons into physically meaningful information on the spectrum of pure Yang-Mills gauge theories, which is believed to exist out of glueballs. We discuss brand-new estimates for the masses of the lightest 3 glueball states (0^++ , 0^-+, 2++), which compare fairly well with known lattice data. We also introduce the concept of i-particles, which are extremely useful in constructing the necessary spectral representations.

Horário: 15:00.

Local: Sala 201, 2º andar.