1,129 research outputs found
Confinement Phase in Carbon-Nanotubes and the Extended Massive Schwinger Model
Full text linkCarbon nanotube with electric fluxes confined in one dimension is studied. We
show that a Coulomb interaction \propto |x| leads to a confinement phase with
many properties similar to QCD in 4D. Low-energy physics is described by the
massive Schwinger model with multi-species fermions labeled by the band and
valley indices. We propose two means to detect this state. One is through an
optical measurement of the exciton spectrum, which has been calculated via the
't Hooft-Berknoff equation with the light-front field theory. We show that the
Gell-Mann-Oakes-Renner relation is satisfied by a dark exciton. The second is
the nonlinear transport which is related to Coleman's "half-asymptotic" state.Comment: 5 pages, 3 figure
A consistent description of the pairing symmetry in hole and electron doped cuprates within the two dimensional Hubbard model
Full text linkQuantum Monte Carlo is used to calculate various pairing correlations of the
2D Hubbard model possessing band features experimentally observed in the
cuprates. In the hole-doped case, where the Fermi level lies close to the van
Hove singularities around , the d pairing correlation is
selectively enhanced, while in the electron-doped case, where the singularities
are far below the Fermi level and the Fermi surface runs through , both d and d correlations are enhanced
with the latter having a structure. The two pairing
symmetries can mix to result in a nodeless gap.Comment: 4 pages, RevTeX, uses epsf.sty and multicol.st
Dirac electrons on three-dimensional graphitic zeolites --- a scalable mass gap
Full text linkA class of graphene wound into three-dimensional periodic curved surfaces
("graphitic zeolites") is proposed and their electronic structures are obtained
to explore how the massless Dirac fermions behave on periodic surfaces. We find
in the tight-binding model that the low-energy band structure around the charge
neutrality point is dominated by the topology (cubic or gyroid) of the periodic
surface as well as by the spatial period in modulo 3 in units of the
lattice constant. In both of cubic and gyroid cases the Dirac electrons become
massive around the charge neutrality point, where the band gap is shown to
scale as within each mod-3 class. Wave functions around the gap are found
to have amplitudes sharply peaked around the topological defects that are
required to deform the graphene sheet into a three-dimensional periodic
surface, and this is shown to originate from non-trivial Bloch phases at
and points of the original graphene.Comment: 5 pages, 6 figure
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