1,166 research outputs found
Vortices, zero modes and fractionalization in bilayer-graphene exciton condensate
A real-space formulation is given for the recently discussed exciton
condensate in a symmetrically biased graphene bilayer. We show that in the
continuum limit an oddly-quantized vortex in this condensate binds exactly one
zero mode per valley index of the bilayer. In the full lattice model the zero
modes are split slightly due to intervalley mixing. We support these results by
an exact numerical diagonalization of the lattice Hamiltonian. We also discuss
the effect of the zero modes on the charge content of these vortices and deduce
some of their interesting properties.Comment: (v2) A typo in Fig. 1 and a slight error in Eq. (4) corrected; all
the main results and conclusions remain unchange
Is there an attraction between spinons in the Haldane--Shastry model?
While the Bethe Ansatz solution of the Haldane--Shastry model appears to
suggest that the spinons represent a free gas of half-fermions, Bernevig,
Giuliano, and Laughlin (BGL) (cond-mat/0011069, cond-mat/0011270) have
concluded recently that there is an attractive interaction between spinons. We
argue that the dressed scattering matrix obtained with the asymptotic Bethe
Ansatz is to be interpreted as the true and physical scattering matrix of the
excitations, and hence, that the result by BGL is inconsistent with an earlier
result by Essler (cond-mat/9406081). We critically re-examine the analysis of
BGL, and conclude that there is no interaction between spinons or spinons and
holons in the Haldane--Shastry model
ON THERMODYNAMICS OF MULTISPECIES ANYONS
We address the problem of multispecies anyons, i.e. particles of different
species whose wave function is subject to anyonlike conditions. The cluster and
virial coefficients are considered. Special attention is paid to the case of
anyons in the lowest Landau level of a strong magnetic field, when it is
possible (i) to prove microscopically the equation of state,
in particular in terms of Aharonov-Bohm charge-flux composite systems, and
(ii) to formulate the problem in terms of single-state statistical
distributions.Comment: Latex, 19 page
Probing non-Abelian statistics of Majorana fermions in ultracold atomic superfluid
We propose an experiment to directly probe the non-Abelian statistics of
Majorana fermions by braiding them in an s-wave superfluid of ultracold atoms.
We show different orders of braiding operations give orthogonal output states
that can be distinguished through Raman spectroscopy. Realization of Majorana
bound states in an s-wave superfluid requires strong spin-orbital coupling and
a controllable Zeeman field in the perpendicular direction. We present a simple
laser configuration to generate the artificial spin-orbital coupling and the
required Zeeman field in the dark state subspace.Comment: 4 pages; Add detailed discussion of feasibility of the scheme;add
ref
The strong-CP question in SU(3)_c X SU(3)_L X U(1)_N models
We analyze two recent models based on the gauge group
SU(3)SU(3)U(1) where each generation is not
anomaly-free, but anomaly cancels when three generations are taken into
account. We show that the most general Yukawa couplings of these models admit
of a Peccei-Quinn symmetry. This symmetry can be extended to the entire
Lagrangian by using extra fields in a very elegant way so that the resulting
axion can be made invisible.Comment: Latex, 8 pages, no figure
Second Virial Coefficient for Noncommutative Space
The second virial coefficient for non-interacting particles
moving in a two-dimensional noncommutative space and in the presence of a
uniform magnetic field is presented. The noncommutativity parameter
\te can be chosen such that the can be interpreted as the
second virial coefficient for anyons of statistics \al in the presence of
and living on the commuting plane. In particular in the high
temperature limit \be\lga 0, we establish a relation between the parameter
\te and the statistics \al. Moreover, can also be
interpreted in terms of composite fermions.Comment: 11 pages, misprints corrected and references adde
Systematic Study Of Leptonic Mixing In A Class Of SU_H(2) Models
We perform a systematic analysis of the PMNS matrices which arise when one
assigns the three generations of leptons to the representation of a
horizontal symmetry. This idea has been previously explored by
Kuchimanchi and Mohapatra. However, we assume the neutrino mass matrix
results from leptonic couplings to triplet scalar fields and
hierarchies exist amongst lepton mass matrix elements which result from
couplings to scalar fields with different charges. Of the sixteen
candidate PMNS matrices which result it is found that only one is both
predictive and possesses a leading order structure compatible with experimental
data. The relevant neutrino mass matrix displays the symmetry
to leading order and we explore the perturbations required
to produce a realistic lepton spectrum. The effective mass in neutrinoless
double beta decay is required to lie in the range
, which is just below current
experimental bounds. is non-zero but not uniquely determined.Comment: To appear in Phys. Rev.
Quantum Numbers of Textured Hall Effect Quasiparticles
We propose a class of variational wave functions with slow variation in spin
and charge density and simple vortex structure at infinity, which properly
generalize both the Laughlin quasiparticles and baby Skyrmions. We argue that
the spin of the corresponding quasiparticle has a fractional part related in a
universal fashion to the properties of the bulk state, and propose a direct
experimental test of this claim. We show that certain spin-singlet quantum Hall
states can be understood as arising from primary polarized states by Skyrmion
condensation.Comment: 13 pages, no figures, Phyzz
Extended Poincar\'e supersymmetry in three dimensions and supersymmetric anyons
We classify the unitary representations of the extended Poincar\'e
supergroups in three dimensions. Irreducible unitary representations of any
spin can appear, which correspond to supersymmetric anyons. Our results also
show that all irreducible unitary representations necessarily have physical
momenta. This is in sharp contrast to the ordinary Poincar\'e group in three
dimensions, that admits in addition irreducible unitary representations with
non-physical momenta, which are discarded on physical grounds.Comment: 7 pages; commentaries added in Sect. IV A and in Conclusion; added
reference
Sublattice ordering in a dilute ensemble of defects in graphene
Defects in graphene, such as vacancies or adsorbents attaching themselves to
carbons, may preferentially take positions on one of its two sublattices, thus
breaking the global lattice symmetry. This leads to opening a gap in the
electronic spectrum. We show that such a sublattice ordering may spontaneously
occur in a dilute ensemble defects, due to the long-range interaction between
them mediated by electrons. As a result sublattice-ordered domains may form,
with electronic properties characteristic of a two-dimensional topological
insulator.Comment: to appear in Europhysics Letter
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