20,905 research outputs found
Conversion of K-Rb mixtures into stable molecules
We study the conversion of K and Rb atoms into stable molecules
through the stimulated Raman adiabatic passage (STIRAP) in photoassociation
assisted with Feshbach resonance. Starting with the mean-field Langrange
density, we show that the atom-to-molecule conversion efficiency by STIRAP
aided by Feshbach resonance is much larger than that by bare Feshbach
resonance. We also study the influence of the population imbalance on the
atom-to-molecule conversion.Comment: Revtex, 5 pages, 3 figures; version to appear in PRA (some content
changed
An approximation theory for the identification of linear thermoelastic systems
An abstract approximation framework and convergence theory for the identification of thermoelastic systems is developed. Starting from an abstract operator formulation consisting of a coupled second order hyperbolic equation of elasticity and first order parabolic equation for heat conduction, well-posedness is established using linear semigroup theory in Hilbert space, and a class of parameter estimation problems is then defined involving mild solutions. The approximation framework is based upon generic Galerkin approximation of the mild solutions, and convergence of solutions of the resulting sequence of approximating finite dimensional parameter identification problems to a solution of the original infinite dimensional inverse problem is established using approximation results for operator semigroups. An example involving the basic equations of one dimensional linear thermoelasticity and a linear spline based scheme are discussed. Numerical results indicate how the approach might be used in a study of damping mechanisms in flexible structures
Casimir pistons with hybrid boundary conditions
The Casimir effect giving rise to an attractive or repulsive force between
the configuration boundaries that confine the massless scalar field is
reexamined for one to three-dimensional pistons in this paper. Especially, we
consider Casimir pistons with hybrid boundary conditions, where the boundary
condition on the piston is Neumann and those on other surfaces are Dirichlet.
We show that the Casimir force on the piston is always repulsive, in contrast
with the same problem where the boundary conditions are Dirichlet on all
surfaces.Comment: 8 pages, 4 figures,references added, minor typos correcte
Identification of Colour Reconnection using Factorial Correlator
A new signal is proposed for the colour reconnection in the hadronic decay of
W+ W- in e+e- collisions. Using Pythia Monte Carlo it is shown that this
signal, being based on the factorial correlator, is more sensitive than the
ones using only averaged quantities.Comment: 6 pages 1 postscript figur
Mass spectra of Zc and Zb exotic states as hadron molecules
We construct charmonium-like and bottomonium-like molecular interpolating
currents with quantum numbers J(PC)=1(+-) in a systematic way, including both
color singlet-singlet and color octet-octet structures. Using these
interpolating currents, we calculate two-point correlation functions and
perform QCD sum rule analyses to obtain mass spectra of the charmonium-like and
bottomonium-like molecular states. Masses of the charmonium-like q_bar c c_bar
q molecular states for these various currents are extracted in the range
3.85-4.22 GeV, which are in good agreement with observed masses of the Zc
resonances. Our numerical results suggest a possible landscape of hadronic
molecule interpretations of the newly-observed Zc states. Mass spectra of the
bottomonium-like q_bar b b_bar q molecular states are similarly obtained in the
range 9.92-10.48 GeV, which support the interpretation of the Zb(10610) meson
as a molecular state within theoretical uncertainties. Possible decay channels
of these molecular states are also discussed.Comment: 15 pages, 3 figures, 2 tables, accepted by PR
Density-functional theory study of half-metallic heterostructures: interstitial Mn in Si
Using density-functional theory within the generalized gradient
approximation, we show that Si-based heterostructures with 1/4 layer
-doping of {\em interstitial} Mn (Mn) are
half-metallic. For Mn concentrations of 1/2 or 1 layer, the
states induced in the band gap of -doped heterostructures still display
high spin polarization, about 85% and 60%, respectively. The proposed
heterostructures are more stable than previously assumed -layers of
{\em substitutional} Mn. Contrary to wide-spread belief, the present study
demonstrates that {\em interstitial} Mn can be utilized to tune the magnetic
properties of Si, and thus provides a new clue for Si-based spintronics
materials.Comment: 5 pages, 4 figures, PRL accepte
One-side forward-backward asymmetry at the LHC
Forward-backward asymmetry is an essential observable to study
the nature of coupling in the standard model and physics beyond the standard
model, as shown at LEP and Tevatron. As a proton-proton collider, the LHC does
not have the preferred direction contrary to her counterpart, namely, LEP and
Tevatron. Therefore is not applicable at the LHC. However for the
proton the momentum of valence quark is usually larger than that of the sea
quark. Utilizing this feature we have defined a so-called one-side
forward-backward asymmetry for the top quark pair production at
LHC in the previous work. In this paper we extend our studies to the charged
leptons and bottom quarks as the final states. Our numerical results show that
at the LHC can be utilized to study the nature of the couplings
once enough events are collected.Comment: 19 pages, 7 figures, 1 table, published versio
SPATIAL DEPENDENCE AMONG COUNTY-LEVEL LAND USE CHANGES
Spatial econometric methods are used to investigate whether land use changes in one county are affected by changes in surrounding counties. Spatial dependence is hypothesized to arise from land substitution effects among neighboring counties. The estimation uses data on land use change for 1,055 counties of 12 Midwest states.Land Economics/Use,
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