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SUMMARY:The Physics of Glueballs
DTSTART;VALUE=DATE-TIME:20081209T140000Z
DTEND;VALUE=DATE-TIME:20081209T150000Z
DTSTAMP;VALUE=DATE-TIME:20261110T074559Z
UID:indico-event-1667@indico.ific.uv.es
DESCRIPTION:Quantum Chromodynamics (QCD) is the modern theory of the stron
 g interaction. QCD allows the coupling of gluons\, the gauge particles of 
 the interaction\, among them and therefore the theory with only gluons is 
 non trivial. Glueballs\, the bound states of gluons\, are a beautiful cons
 equence of self coupling. I review the recent developments on glueball spe
 ctroscopy with a special emphasis on constituent models. The problematic o
 n the mixing with nearby mesons leads to difficulties in the identificatio
 n of physical states. I therefore restrict my models to the pure gauge the
 ory . The pure gauge spectrum of quarkless QCD was investigated by Morning
 star and Peardon on a lattice. They identified 15 glueballs below 4 GeV bo
 th in C = + and C = −. In a constituent picture\, the low-lying states a
 re bound states of two gluons with C = +. A negative charge conjugation re
 quires at least three gluons. In the usual picture\, the gluon is a heavy 
 spin-1 particle since the gauge boson gains a dynamical mass induced by no
 n-perturbative effects. This consideration leads to gluonium pictures for 
 two- and three-gluon glueballs which are extrapolation of meson and baryon
  systems. However I show that the usual LS-coupling scheme cannot reproduc
 e the lattice spectrum. This formalism is indeed irrelevant to handle tran
 sverse particles such as gluons. The implementation of the helicity formal
 ism for two-gluons glueballs leads to a spectrum in perfect agreement with
  the lattice results even without the inclusion of short-range spin-splitt
 ing potentials.\n\nhttps://indico.ific.uv.es/event/1667/
LOCATION:Dpto. de Física Teórica (UVEG) Sala Seminarios
URL:https://indico.ific.uv.es/event/1667/
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