National Science Center "Kharkov Institute of Physics & Technology",

1 Akademicheskaya Str.,

61108 Kharkov, UKRAINE

E-mail: ivashin@kipt.kharkov.ua, mic@kharkov.ua

*L.V. LOGVINOVA*

Belgorod State University,

Belgorod, RUSSIA

**Classification of equilibrium states of condensed media
with spontaneously broken symmetry**

**Abstract:**

In the present paper the classification of equilibrium states of condensed
media with spontaneously broken symmetry is carried out in view of possible
nonuniform structure. The used approach is founded on the quasiaverages
concept [1, 2]. The admissible properties of equilibrium state symmetry
of a quantum fluid and relevant structures of an order parameter are found
from requirements of the residual and spatial symmetry at nonzero values
of an order parameter. This approach is founded on the representation of
the residual symmetry of the degenerated equilibrium state as a subgroup
of a normal phase symmetry. The superfluid liquid in a state with singlet
and triplet pairing [3, 4], the superfluid nuclear matter in a state of
d-pairing [5], liquid crystal states of matter are consedered in this paper
as the axamples. Admissible conditions of the spatial symmetry and the
general structure of the corresponding generator are found. The requirement
of residual symmetry is expanded on the inhomogeneous equilibrium states,
the relation to the homogeneous case has been found.

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