24,182 research outputs found
Non-Hermitian robust edge states in one-dimension: Anomalous localization and eigenspace condensation at exceptional points
Capital to topological insulators, the bulk-boundary correspondence ties a
topological invariant computed from the bulk (extended) states with those at
the boundary, which are hence robust to disorder. Here we put forward an
ordering unique to non-Hermitian lattices, whereby a pristine system becomes
devoid of extended states, a property which turns out to be robust to disorder.
This is enabled by a peculiar type of non-Hermitian degeneracy where a
macroscopic fraction of the states coalesce at a single point with geometrical
multiplicity of , that we call a phenomenal point.Comment: 6 pages, 4 figure
Structure and three-body decay of Be resonances
The complex-rotated hyperspherical adiabatic method is used to study the
decay of low-lying Be resonances into one neutron and two
-particles. We investigate the six resonances above the break-up
threshold and below 6 MeV: , and . The
short-distance properties of each resonance are studied, and the different
angular momentum and parity configurations of the Be and He two-body
substructures are determined. We compute the branching ratio for sequential
decay via the Be ground state which qualitatively is consistent with
measurements. We extract the momentum distributions after decay directly into
the three-body continuum from the large-distance asymptotic structures. The
kinematically complete results are presented as Dalitz plots as well as
projections on given neutron and -energy. The distributions are
discussed and in most cases found to agree with available experimental data.Comment: 12 pages, 10 figures. To appear in Physical Review
Competition between noise and coupling in the induction of synchronisation.
We apply a Fokker-Planck analysis to investigate the relative influences of coupling strength and noise on the synchronisation of two phase oscillators. We go beyond earlier studies of noise-induced synchronisation (without couplings) and coupling-induced synchronisation (without common noise) to consider both effects together, and we obtain a result that is very different from a straightforward superposition of the effects of each agent acting alone: two regimes are possible depending on which agent is inducing the synchronisation. In each regime, one agent induces and the other hinders the synchronisation. In particular we show that, counterintuitively, coupling can sometimes inhibit synchronisation
Momentum distributions from three-body decaying 9Be and 9B resonances
The complex-rotated hyperspherical adiabatic method is used to study the
decay of low-lying Be and B resonances into , and
or . We consider six low-lying resonances of Be (,
and ) and one resonance of B () to compare with. The
properties of the resonances at large distances are decisive for the momentum
distributions of the three decaying fragments. Systematic detailed energy
correlations of Dalitz plots are presented.Comment: 4 pages, 2 figures. Proceedings of the SOTANCP2 conference held in
Brussels in May 201
Coexistence of Pairing Tendencies and Ferromagnetism in a Doped Two-Orbital Hubbard Model on Two-Leg Ladders
Using the Density Matrix Renormalization Group and two-leg ladders, we
investigate an electronic two-orbital Hubbard model including plaquette
diagonal hopping amplitudes. Our goal is to search for regimes where charges
added to the undoped state form pairs, presumably a precursor of a
superconducting state.For the electronic density , i.e. the undoped
limit, our investigations show a robust antiferromagnetic ground
state, as in previous investigations. Doping away from and for large
values of the Hund coupling , a ferromagnetic region is found to be stable.
Moreover, when the interorbital on-site Hubbard repulsion is smaller than the
Hund coupling, i.e. for in the standard notation of multiorbital Hubbard
models, our results indicate the coexistence of pairing tendencies and
ferromagnetism close to . These results are compatible with previous
investigations using one dimensional systems. Although further research is
needed to clarify if the range of couplings used here is of relevance for real
materials, such as superconducting heavy fermions or pnictides, our theoretical
results address a possible mechanism for pairing that may be active in the
presence of short-range ferromagnetic fluctuations.Comment: 8 pages, 4 Fig
Poisson-Lie T-duality and N=2 superconformal WZNW models on compact groups
The supersymmetric generalization of Pisson-Lie T-duality in N=2
superconformal WZNW models on the compact groups is considered. It is shown
that the role of Drinfeld's doubles play the complexifications of the
corresponding compact groups. These complex doubles are used to define the
natural actions of the isotropic subgroups forming the doubles on the group
manifolds of the N=2 superconformal WZNW models. The Poisson- Lie T-duality in
N=2 superconformal U(2)-WZNW model considered in details. It is shown that this
model admits Poisson-Lie symmetries with respect to the isotropic subgroups
forming Drinfeld's double Gl(2,C). Poisson-Lie T-duality transformation maps
this model into itself but acts nontrivialy on the space of classical
solutions. Supersymmetric generalization of Poisson-Lie T-duality in N=2
superconformal WZNW models on the compact groups of higher dimensions is
proposed.Comment: 12 pages, latex, misprints correcte
Spacetime and the Holographic Renormalization Group
Anti-de Sitter (AdS) space can be foliated by a family of nested surfaces
homeomorphic to the boundary of the space. We propose a holographic
correspondence between theories living on each surface in the foliation and
quantum gravity in the enclosed volume. The flow of observables between our
``interior'' theories is described by a renormalization group equation. The
dependence of these flows on the foliation of space encodes bulk geometry.Comment: 12 page
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