Gluon Sector Research Articles

Deconfinement and virtual quark loops

We calculate paer Monte Carlo evaluation on an 8 3 × 3 lattice the energy density ϵ G of the gluon sector of QCD, including virtual quark loops up to the fourth power in the hopping parameter expansion. For light quarks of one flavour, we observe at T/ Λ L 95 ± 10 a rapid variation of ϵ G in T, accompanied by strong fluctuations from iteration to iteration. as clear signal of the deconfinement transition.

Variational calculations in the gluon sector of the lattice QCD

The partition function ofd dimensional systems is estimated with the help of a variational Ansatz in terms of quasi-(d-1)-dimensional systems. The internal energy and the string tension derived in this framework agree reasonably with the Monte Carlo data.

Low mass glueballs in the meson spectrum

The spectrum of bound states of gluons is discussed within the MIT bag model. We argue that (1) contrary to previous analysis there is no light exotic 1 −+ state in the two gluon sector, (2) experiments on the three gluon sector can clearly differentiate the bag model from other models, (3) the state seen in J/ ψ radiative decays at 1.4 GeV is most likely a pseudoscalar glueball, and (4) there should be a second 2 ++ state underneath the f(1270) resonance.

Strong coupling 1/N c expansion in the gluonic sector of lattice QCD: The next order

Continuing our previous work we determin- ed the gluonic vacuum state up to sixth order and the lowest states with external quark-antiquark and (unscreened) gluon-gluon sources up to fourth order in the strong coupling 1/N c expansion on the lattice. Unlike previously, we used here the colour electric flux operators on the links to define the colour electric energy. Additional remarks concern- ing the screening of external gluon sources and the analytic continuation to N c = 3 and zero lattice spacing are also included.

Strong coupling 1/N c expansion in the gluonic sector of lattice quantum chromodynamics

The vacuum state of gluonic quantum chromodynamics on the lattice is determined up to fifth order in a 1/N c expansion (N c=number of colours). The vacuum expectation value of the gluon field squaredF aμvF a μv is deduced. The quark-antiquark and gluon-gluon potential is calculated in the same limit up to the 1/N c 3 order.

Verification of mass shell Ward identities for gluons in the axial gauge

The one-gluon-loop contributions to the mass shell renormalization constants in the gluonic sector of quantum chromodynamics are considered in the axial gauge. By means of dimensional regularization it is demonstrated explicitly that these contributions satisfy the general Ward identities proven in a previous work. In fact, all one-gluon-loop corrections vanish on the mass shell.

Mass shell behaviour of quantum chromodynamics in the axial gauge

It is shown that, in the noncovariant axial gauge, quark and gluon mass shell renormalization constants (if suitably defined) obey the classic Ward identity of quantum electrodynamicsZ1=Z2. Similar relations hold for the pure gluon sector. The validity of such identities in covariant gauges has been proven recently in the literature. The derivation in the axial gauge is considerably simpler than in covariant gauges.