Color structure of gluon field magnetic mass

The color structure of the gluon field magnetic mass is investigated in the lattice SU(2) gluodynamics. To realize that the interaction between a monopole–antimonopole string and external neutral Abelian chromomagnetic field flux is considered. The string is introduced in the way proposed by Srednicki and Susskind. The neutral Abelian field flux is introduced through the twisted boundary conditions. Monte Carlo simulations are performed on 4D lattices at finite temperature. It is shown that the presence of the Abelian field flux weakens the screening of the string field. That means decreasing the gluon magnetic mass for this environment. The contribution of the neutral Abelian field has the form of “enhancing” factor in the fitting functions. This behavior independently confirms the long-range nature of the neutral Abelian field reported already in the literature. The comparison with analytic calculations is given.

Bag formation from gauge condensate

As it is well known, one can lower the energy of the trivial perturbation QCD vacuum by introducing a nonvanishing chromomagnetic field strength. This happens because radiative corrections produce an effective action of the form [Formula: see text] with f′(y0) = 0 for some y0≠0. However, a vacuum with a nonzero field strength is not consistent with Poincaré Invariance (PI). Generalizing this type of effective action by introducing, in the simplest way, a four-index field strength ∂[μAναβ], which can have an expectation value without violating PI, we are lead to an effective action that can describe both a confinement phase and a perturbative phase of the theory. In the unconfined phase, the four-index field strength does not introduce new degrees of freedom, while in the confined phase both four-index field strength and ordinary gauge fields are not true degrees of freedom. The matching of these phases through membranes that couple minimally to the three-index potentials from which the four-index field strength derive, leads automatically to the MIT bag boundary conditions for the gauge fields living inside the bubble containing the perturbative phase.

LONG RANGE CHROMOMAGNETIC FIELDS AT HIGH TEMPERATURE

The magnetic mass of neutral gluons in Abelian chromomagnetic field at high temperature is calculated in SU(2) gluodynamics. It is noted that such fields are spontaneously generated at high temperature. The mass is computed either from the Schwinger–Dyson equation accounting for the one-loop polarization tensor or in Monte Carlo simulations on a lattice. In latter case, an average magnetic flux penetrating a plaquette is measured for a number of lattices. Both calculations are in agreement with each other and result in zero magnetic mass. Some applications of the results obtained are discussed.

Colored scalar in a chromomagnetic field

The motion of colored scalar particles in a constant color magnetic field is considered. The Klein-Gordon equation is solved in this background and the energy spectrum is quantized by boundary conditions. The unitary transformation diagonalizing this equation and the states with definite energy are found.