2,487 research outputs found
Switching off the magnetic exchange coupling by quantum resonances
We clarify the role of quantum-well states in magnetic trilayer systems from
majority carrier in the ferromagnetic and all carriers in the antiferromagnetic
configurations. In addition to numerical and analytic calculations, heuristic
pictures are provided to explain effects of a capping layer and side-layer
modulation in recent experiments. This immediately offers answers to two
unexplained subtle findings in experiments and band-structure calculations,
individually. Furthermore, it allows a more flexible tuning of or even turning
off the interlayer exchange coupling.Comment: 5 pages, 5 figure
Resolving the Degeneracy in Single Higgs Production with Higgs Pair Production
The Higgs boson production can be affected by several anomalous couplings,
e.g. and anomalous couplings. Precise measurement of
production yields two degenerate parameter spaces of and ; one
parameter space exhibits the SM limit while the other does not. Such a
degeneracy could be resolved by Higgs boson pair production. In this work we
adapt the strategy suggested by the ATLAS collaboration to explore the
potential of distinguishing the degeneracy at the 14 TeV LHC. If the
anomalous coupling is induced only by the operator , then the non-SM-like band could be excluded with an integrated luminosity
of . Making use of the fact that the Higgs boson pair
is mainly produced through an -wave scattering, we propose an analytical
function to describe the fraction of signal events surviving a series of
experimental cuts for a given invariant mass of Higgs boson pair. The function
is model independent and can be applied to estimate the discovery potential of
various NP models
Differential measurement of atmospheric refraction with a telescope with double fields of view
For the sake of complete theoretical research of atmospheric refraction, the
atmospheric refraction under the condition of lower angles of elevation is
still worthy to be analyzed and explored. In some engineering applications, the
objects with larger zenith distance must be observed sometimes. Carrying out
observational research of the atmospheric refraction at lower angles of
elevation has an important significance. It has been considered difficult to
measure the atmospheric refraction at lower angles of elevation. A new idea for
determining atmospheric refraction by utilizing differential measurement with
double fields of view is proposed. Taking the observational principle of
HIPPARCOS satellite as a reference, a schematic prototype with double fields of
view was developed. In August of 2013, experimental observations were carried
out and the atmospheric refractions at lower angles of elevation can be
obtained by the schematic prototype. The measured value of the atmospheric
refraction at the zenith distance of 78.8 degree is , and the
feasibility of differential measurement of atmospheric refraction with double
fields of view was justified. The limitations of the schematic prototype such
as inadequate ability of gathering light, lack of accurate meteorological data
recording and lower automatic level of observation and data processing were
also pointed out, which need to be improved in subsequent work.Comment: 10 pages, 6 figure
Spin-quadrupole ordering of spin-3/2 ultracold fermionic atoms in optical lattices in the one-band Hubbard model
Based on a generalized one-band Hubbard model, we study magnetic properties
of Mott insulating states for ultracold spin-3/2 fermionic atoms in optical
lattices. When the \textit{s}-wave scattering lengths for the total spin
satisfy conditions , we apply a functional integral
approach to the half filled case, where the spin-quadrupole fluctuations
dominate. On a 2D square lattice, the saddle point solution yields a staggered
spin-quadrupole ordering at zero temperature with symmetry breaking from SO(5)
to SO(4). Both spin and spin-quadrupole static structure factors are
calculated, displaying highly anisotropic spin antiferromagnetic fluctuations
and antiferroquadrupole long-range correlations, respectively. When Gaussian
fluctuations around the saddle point are taken into account, spin-quadrupole
density waves with a linear dispersion are derived. Compared with the spin
density waves in the half filled spin-1/2 Hubbard model, the quadrupole density
wave velocity is saturated in the strong-coupling limit, and there are no
transverse spin-quadrupole mode couplings, as required by the SO(4) invariance
of the effective action. Finally, in the strong-coupling limit of the model
Hamiltonian, we derive the effective hyperfine spin-exchange interactions for
the Mott insulating phases in the quarter filled and half filled cases,
respectively.Comment: 12 pages, 5 figure
Nonlinear reconstruction
We present a direct approach to nonparametrically reconstruct the linear
density field from an observed nonlinear map. We solve for the unique
displacement potential consistent with the nonlinear density and positive
definite coordinate transformation using a multigrid algorithm. We show that we
recover the linear initial conditions up to the nonlinear scale
( for ) with minimal
computational cost. This reconstruction approach generalizes the linear
displacement theory to fully nonlinear fields, potentially substantially
expanding the baryon acoustic oscillations and redshift space distortions
information content of dense large scale structure surveys, including for
example SDSS main sample and 21cm intensity mapping initiatives.Comment: 7 pages, 7 figures, published versio
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