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Abstract |
We discuss the different ways to study gauge theories phase structure using
lattice regularisation. Lattice approach allows direct numerical study of
nonpertubative phenomena like different topological objects of the gauge field
theory, phase transitions and finite volume effects. The one-dimensional and
two-dimensional operators of SU(2) and compact U(1) theories are discussed. It
is shown that the finite volume effects may lead to a low temperature
deconfinement phase transition induced by the presence of boundaries in
confining gauge theories. At small distances between the boundaries the vacuum
looses the confinement property due to modification of vacuum fluctuations of
virtual monopoles. It is shown that analysis of the string tension sigma in
SU(2)
theory, allows us to draw a conclusion that in very dense cold matter the
quark-gluon plasma is in essence a weakly interacting gas of quarks and gluons
without a magnetic screening mass in the system, sharply different from a
quark-gluon plasma at large temperature. |
