15,636 research outputs found
How is chiral symmetry restored at finite density?
Taking into account pseudoscalar as well as scalar condensates, we reexamine
the chiral restoration path on the chiral manifold. We shall see both
condensates coherently produce a density wave at a certain density, which
delays chiral restoration as density or temperature is increased.Comment: 4 pages, 2 figures; proc. of QM0
Spin of the ground state and the flux phase problem on the ring
As a continuation of our previous work, we derive the optimal flux phase
which minimizes the ground state energy in the one-dimensional many particle
systems, when the number of particles is odd in the absence of on-site
interaction and external potential. Moreover, we study the relationship between
the flux on the ring and the spin of the ground state through which we derive
some information on the sum of the lowest eigenvalues of one-particle
Hamiltonians
Drude Weight of the Two-Dimensional Hubbard Model -- Reexamination of Finite-Size Effect in Exact Diagonalization Study --
The Drude weight of the Hubbard model on the two-dimensional square lattice
is studied by the exact diagonalizations applied to clusters up to 20 sites. We
carefully examine finite-size effects by consideration of the appropriate
shapes of clusters and the appropriate boundary condition beyond the imitation
of employing only the simple periodic boundary condition. We successfully
capture the behavior of the Drude weight that is proportional to the squared
hole doping concentration. Our present result gives a consistent understanding
of the transition between the Mott insulator and doped metals. We also find, in
the frequency dependence of the optical conductivity, that the mid-gap
incoherent part emerges more quickly than the coherent part and rather
insensitive to the doping concentration in accordance with the scaling of the
Drude weight.Comment: 9 pages with 10 figures and 1 table. accepted in J. Phys. Soc. Jp
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