1,138 research outputs found
Particle-hole symmetry and interaction effects in the Kane-Mele-Hubbard model
We prove that the Kane-Mele-Hubbard model with purely imaginary
next-nearest-neighbor hoppings has a particle-hole symmetry at half-filling.
Such a symmetry has interesting consequences including the absence of charge
and spin currents along open edges, and the absence of the sign problem in the
determinant quantum Monte-Carlo simulations. Consequentially, the interplay
between band topology and strong correlations can be studied at high numeric
precisions. The process that the topological band insulator evolves into the
antiferromagnetic Mott insulator as increasing interaction strength is studied
by calculating both the bulk and edge electronic properties. In agreement with
previous theory analyses, the numeric simulations show that the
Kane-Mele-Hubbard model exhibits three phases as increasing correlation
effects: the topological band insulating phase with stable helical edges, the
bulk paramagnetic phase with unstable edges, and the bulk antiferromagnetic
phase
Simplified TeV leptophilic dark matter in light of DAMPE data
Using a simplified framework, we attempt to explain the recent DAMPE cosmic
flux excess by leptophilic Dirac fermion dark matter (LDM). The
scalar () and vector () mediator fields connecting LDM and
Standard Model particles are discussed. Under constraints of DM relic density,
gamma-rays, cosmic-rays and Cosmic Microwave Background (CMB), we find that the
couplings , , and can
produce the right bump in flux for a DM mass around 1.5 TeV with a
natural thermal annihilation cross-section today. Among them, coupling is tightly constrained by
PandaX-II data (although LDM-nucleus scattering appears at one-loop level) and
the surviving samples appear in the resonant region, . We also study the related collider signatures, such as dilepton
production , and muon anomaly. Finally,
we present a possible realization for such leptophilic dark matter.Comment: discussions added, version accepted by JHE
Synthetic Landau levels and spinor vortex matter on Haldane spherical surface with magnetic monopole
We present a flexible scheme to realize exact flat Landau levels on curved
spherical geometry in a system of spinful cold atoms. This is achieved by
Floquet engineering of a magnetic quadrupole field. We show that a synthetic
monopole field in real space can be created. We prove that the system can be
exactly mapped to the electron-monopole system on sphere, thus realizing
Haldane's spherical geometry for fractional quantum Hall physics. The scheme
works for either bosons or fermions. We investigate the ground state vortex
pattern for an -wave interacting atomic condensate by mapping this system to
the classical Thompson's problem. We further study the distortion and stability
of the vortex pattern when dipolar interaction is present. Our scheme is
compatible with current experimental setup, and may serve as a promising route
of investigating quantum Hall physics and exotic spinor vortex matter on curved
space.Comment: 11 pages, 4 figure
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