845 research outputs found
On the stability of compact supermassive objects
Proceeded from the gravitation equations proposed by one of authors it was
argued in a previous paper that there can exist supermassive compact
configurations of degenerated Fermi-gas without events horizon. In the present
paper we consider the stability of these objects by method like the one used in
the theory of stellar structure. It is shown that the configurations with an
adiabatic equation of state with the power 4/3 are stable.Comment: 10 pages, 5 figure
Effective spin-fermion model for strongly correlated electrons
A modified spin-fermion model is proposed to describe the physics of the
underdoped phase of the t-J model of strongly correlated electron
Limitations of the mean field slave-particle approximations
We show that the transformation properties of the mean field slave
boson/fermion order parameters under an action of the global SU(2) group impose
certain restrictions on their applications to describe the phase diagram of the
t-J model.Comment: to appear in Phys. Rev.
On the extra phase correction to the semiclassical spin coherent-state propagator
The problem of an origin of the Solary-Kochetov extra-phase contribution to
the naive semiclassical form of a generalized phase-space propagator is
addressed with the special reference to the su(2) spin case which is the most
important in applications. While the extra-phase correction to a flat
phase-space propagator can straightforwardly be shown to appear as a difference
between the principal and the Weyl symbols of a Hamiltonian in the
next-to-leading order expansion in the semiclassical parameter, the same
statement for the semiclassical spin coherent-state propagator holds provided
the Holstein-Primakoff representation of the su(2) algebra generators is
employed.Comment: 19 pages, no figures; a more general treatment is presented, some
references are added, title is slightly changed; submitted to JM
On representation of the t-J model via spin-charge variables
We show that the t-J Hamiltonian is not in general reduced to H(S,f), where S
and f stand for independent ([S,f]=0) SU(2) (spin) generators and spinless
fermionic (hole) field, respectively. The proof is based upon an identification
of the Hubbard operators with the generators of the su(2|1) superalgebra in the
degenerate fundamental representation and ensuing SU(2|1) path integral
representation of the partition function.Comment: 15 pages, latex, no figure
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