  The anticorrelated distributions of temperature and density of protons are a
well-known property of the solar wind. Nevertheless, it is unclear till now if
they are formed by some kind of the universal physical mechanism?
Unfortunately, a straightforward comparison of the characteristic relaxation
times for the temperature and density, on the one hand, and pressure, on the
other hand, encounters the problem of inapplicability of the hydrodynamical
approach in the situation when the free-path length of the protons is
considerably greater than the spatial scale of the structures under
consideration. To resolve this problem, some kinds of the MHD turbulence -
reducing the effective free paths - are usually assumed. In the present paper,
we use an alternative approach based on the electrostatic (Langmuir)
turbulence, described by the mathematical formalism of the spin-type
Hamiltonians, which was actively discussed in the recent time in the literature
on statistical physics. As follows from the corresponding calculations,
formation of the anticorrelated distributions of temperature and density is a
universal property of the strongly-nonequilibrium plasmas governed by the
spin-type Hamiltonians when they gradually approach the thermodynamic
equilibrium. So, just this phenomenon could be responsible for the
anticorrelations observed in the solar wind.
