8,817 research outputs found
The Atomic Lighthouse Effect
We investigate the deflection of light by a cold atomic cloud when the
light-matter interaction is locally tuned via the Zeeman effect using magnetic
field gradients. This "lighthouse" effect is strongest in the single-scattering
regime, where deviation of the incident field is largest. For optically dense
samples, the deviation is reduced by collective effects, as the increase in
linewidth leads to a decrease of the magnetic field efficiency
Spatial and temporal localization of light in two dimensions
Quasi-resonant scattering of light in two dimensions can be described either
as a scalar or as a vectorial electromagnetic wave. Performing a scaling
analysis we observe in both cases long lived modes, yet only the scalar case
exhibits Anderson localized modes together with extremely long mode lifetimes.
We show that the localization length of these modes is influenced only by their
position, and not their lifetime. Investigating the reasons for the absence of
localization, it appears that both the coupling of several polarizations and
the presence of near-field terms are able to prevent long lifetimes and
Anderson localization.Comment: 5 pages, 4 figures and Supplementary Informatio
Electroweak corrections and anomalous triple gauge-boson couplings in WW and WZ production at the LHC
We have analysed the production of WW and WZ vector-boson pairs at the LHC.
These processes give rise to four-fermion final states, and are particularly
sensitive to possible non-standard trilinear gauge-boson couplings. We have
studied the interplay between the influence of these anomalous couplings and
the effect of the complete logarithmic electroweak O(\alpha) corrections.
Radiative corrections to the Standard Model processes in double-pole
approximation and non-standard terms due to trilinear couplings are implemented
into a Monte Carlo program for p p -> 4f (+\gamma) with final states involving
four or two charged leptons. We numerically investigate purely leptonic final
states and find that electroweak corrections can fake new-physics signals,
modifying the observables by the same amount and shape, in kinematical regions
of statistical significance.Comment: 19 pages, LaTex, 12 eps figure
Correlation Function in Deep Redshift Space as a Cosmological Probe
Recent development of galaxy surveys enables us to investigate the deep
universe of high redshift. We quantitatively present the physical information
extractable from the observable correlation function in deep redshift space in
a framework of the linear theory. The correlation function depends on the
underlying power spectrum, velocity distortions, and the Alcock-Paczy\'nski
(AP) effect. The underlying power spectrum is sensitive to the constituents of
matters in the universe, the velocity distortions are sensitive to the galaxy
bias as well as the amount of total matter, and the Alcock-Paczy\'nski effect
is sensitive to the dark energy components. Measuring the dark energy by means
of the baryonic feature in the correlation function is one of the most
interesting applications. We show that the ``baryon ridge'' in the correlation
function serves as a statistically circular object in the AP effect. In order
to sufficiently constrain the dark energy components, the redshift range of the
galaxy survey should be as broad as possible. The survey area on the sky should
be smaller at deep redshifts than at shallow redshifts to keep the number
density as dense as possible. We illustrate an optimal survey design that are
useful in cosmology. Assuming future redshift surveys of z\simlt 3 which are
within reach of the present-day technology, achievable error bounds on
cosmological parameters are estimated by calculating the Fisher matrix.
According to an illustrated design, the equation of state of dark energy can be
constrained within error assuming that the bias is unknown and
marginalized over. Even when all the other cosmological parameters should be
simultaneously determined, the error bound for the equation of state is up to
.Comment: 13 pages, 8 figures, ApJ in pres
Curie-like paramagnetism due to incomplete Zhang-Rice singlet formation in La2-xSrxCuO4
In an effort to elucidate the origin of the Curie-like paramagnetism that is
generic for heavily-overdoped cuprates, we have performed high transverse-field
muon spin rotation (TF-muSR) measurements of La2-xSrxCuO4 single crystals over
the Sr content range 0.145 < x < 0.33. We show that the x-dependence of the
previously observed field-induced broadening of the internal magnetic field
distribution above the superconducting transition temperature Tc reflects the
presence of two distinct contributions. One of these becomes less pronounced
with increasing x and is attributed to diminishing antiferromagnetic
correlations. The other grows with increasing x, but decreases above x ~ 0.30,
and is associated with the Curie-like term in the bulk magnetic susceptibility.
In contrast to the Curie-like term, however, this second contribution to the
TF-muSR line width extends back into the underdoped regime. Our findings imply
a coexistence of antiferromagnetically correlated and paramagnetic moments,
with the latter becoming dominant beyond x ~ 0.185. This suggests that the
doped holes do not neutralize all Cu spins via the formation of Zhang-Rice
singlets. Moreover, the paramagnetic component of the TF-muSR line width is
explained by holes progressively entering the Cu 3d_{x^2-y^2} orbital with
doping.Comment: 8 pages, 7 figure
Forecasting the Cosmological Constraints with Anisotropic Baryon Acoustic Oscillations from Multipole Expansion
Baryon acoustic oscillations (BAOs) imprinted in the galaxy power spectrum
can be used as a standard ruler to determine angular diameter distance and
Hubble parameter at high redshift galaxies. Combining redshift distortion
effect which apparently distorts the galaxy clustering pattern, we can also
constrain the growth rate of large-scale structure formation. Usually, future
forecast for constraining these parameters from galaxy redshift surveys has
been made with a full 2D power spectrum characterized as function of wavenumber
and directional cosine between line-of-sight direction and wave
vector, i.e., . Here, we apply the multipole expansion to the full 2D
power spectrum, and discuss how much cosmological information can be extracted
from the lower-multipole spectra, taking a proper account of the non-linear
effects on gravitational clustering and redshift distortion. The Fisher matrix
analysis reveals that compared to the analysis with full 2D spectrum, a partial
information from the monopole and quadrupole spectra generally degrades the
constraints by a factor of for each parameter. The additional
information from the hexadecapole spectrum helps to improve the constraints,
which lead to an almost comparable result expected from the full 2D spectrum.Comment: 12 pages, 6 figure
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Change Management Support for Large Software Systems
This technical report consists of three related papers in the area of management of source code changes for large software systems. Infuse: A Toolfor Automatically Managing and Coordinating Source Changes in Large Systems presents Infuse, a software engineering environment that automatically panitions the source code files to be changed in order to limit the complexity of change propagation and negotiation of conflicting changes. Workspaces and Experimental Databases: Automated Support for Cooperation Among Programmers describes Infuse in more detail, focusing on the interactions between Infuse and source code modification tools. Smarter Recompilation presents an algorithm that could be used by Infuse or other software engineering environments to reduce recompilation costs after source code changes
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