6,031 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
A SOCIAL RECOMMENDATION MECHANISM FOR SOCIAL FUNDRAISING
In recent years, the world incurs many social issue and environmental disaster, so charity giving is become popular. Nowadays, the crowdfunding also become popular and the charity usually use specific type of crowdfunding called Peer-to-Peer fundraising. Many donor relationship management software and solutions have appeared. But they rarely utilize power of social network and majority of them focus on the aspect of fundraiser not on the aspect of donors. In this research, we will propose a social supported recommendation mechanism for non-profit fundraising. We will examine the donor preference, relationship between donor and fundraiser, and the characteristic fundraising dynamics to enhance the success rate of fundraising project and satisfaction rate of the donor
The leptonic decay using the principle of maximum conformality
In the paper, we study the leptonic decay width
by using the principle of maximum
conformality (PMC) scale-setting approach. The PMC adopts the renormalization
group equation to set the correct momentum flow of the process, whose value is
independent to the choice of the renormalization scale and its prediction thus
avoids the conventional renormalization scale ambiguities. Using the known
next-to-next-to-next-to-leading order perturbative series together with the PMC
single scale-setting approach, we do obtain a renormalization scale independent
decay width, keV,
where the error is squared average of those from
, GeV and the choices of
factorization scales within of their central values. To compare with
the result under conventional scale-setting approach, this decay width agrees
with the experimental value within errors, indicating the importance of a
proper scale-setting approach.Comment: 6 pages, 4 figure
Is the late near-infrared bump in short-hard GRB 130603B due to the Li-Paczynski kilonova?
Short-hard gamma-ray bursts (GRBs) are widely believed to be produced by the
merger of two binary compact objects, specifically by two neutron stars or by a
neutron star orbiting a black hole. According to the Li-Paczynski kilonova
model, the merger would launch sub-relativistic ejecta and a
near-infrared/optical transient would then occur, lasting up to days, which is
powered by the radioactive decay of heavy elements synthesized in the ejecta.
The detection of a late bump using the {\em Hubble Space Telescope} ({\em HST})
in the near-infrared afterglow light curve of the short-hard GRB 130603B is
indeed consistent with such a model. However, as shown in this Letter, the
limited {\em HST} near-infrared lightcurve behavior can also be interpreted as
the synchrotron radiation of the external shock driven by a wide mildly
relativistic outflow. In such a scenario, the radio emission is expected to
peak with a flux of Jy, which is detectable for current radio
arrays. Hence, the radio afterglow data can provide complementary evidence on
the nature of the bump in GRB 130603B. It is worth noting that good
spectroscopy during the bump phase in short-hard bursts can test validity of
either model above, analogous to spectroscopy of broad-lined Type Ic supernova
in long-soft GRBs.Comment: 4 pages, 2 figures, published in ApJ Lette
Quantum Hall Effects in a Non-Abelian Honeycomb Lattice
We study the tunable quantum Hall effects in a non-Abelian honeycomb optical
lattice which is a many-Dirac-points system. We find that the quantum Hall
effects present different features as change as relative strengths of several
perturbations. Namely, a gauge-field-dressed next-nearest-neighbor hopping can
induce the quantum spin Hall effect and a Zeeman field can induce a so-called
quantum anomalous valley Hall effect which includes two copies of quantum Hall
states with opposite Chern numbers and counter-propagating edge states. Our
study extends the borders of the field of quantum Hall effects in honeycomb
optical lattice when the internal valley degrees of freedom enlarge.Comment: 7 pages, 6 figure
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