364 research outputs found
ILC Operating Scenarios
The ILC Technical Design Report documents the design for the construction of
a linear collider which can be operated at energies up to 500 GeV. This report
summarizes the outcome of a study of possible running scenarios, including a
realistic estimate of the real time accumulation of integrated luminosity based
on ramp-up and upgrade processes. The evolution of the physics outcomes is
emphasized, including running initially at 500 GeV, then at 350 GeV and 250
GeV. The running scenarios have been chosen to optimize the Higgs precision
measurements and top physics while searching for evidence for signals beyond
the standard model, including dark matter. In addition to the certain precision
physics on the Higgs and top that is the main focus of this study, there are
scientific motivations that indicate the possibility for discoveries of new
particles in the upcoming operations of the LHC or the early operation of the
ILC. Follow-up studies of such discoveries could alter the plan for the
centre-of-mass collision energy of the ILC and expand the scientific impact of
the ILC physics program. It is envisioned that a decision on a possible energy
upgrade would be taken near the end of the twenty year period considered in
this report
Dilepton production near partonic threshold in transversely polarized proton-antiproton collisions
It has recently been suggested that collisions of transversely polarized
protons and antiprotons at the GSI could be used to determine the nucleon's
transversity densities from measurements of the double-spin asymmetry for the
Drell-Yan process. We analyze the role of higher-order perturbative QCD
corrections in this kinematic regime, in terms of the available fixed-order
contributions as well as of all-order soft-gluon resummations. We find that the
combined perturbative corrections to the individual unpolarized and
transversely polarized cross sections are large. We trace these large
enhancements to soft gluon emission near partonic threshold, and we suggest
that with a physically-motivated cut-off enhancements beyond lowest order are
moderated relative to resummed perturbation theory, but still significant. The
unpolarized dilepton cross section for the GSI kinematics may therefore provide
information on the relation of perturbative and nonperturbative dynamics in
hadronic scattering. The spin asymmetry turns out to be rather robust,
relatively insensitive to higher orders, resummation, and the cut-offs.Comment: 23 pages, 19 figures as eps. Some discussion and references added.
Final version to appear in Phys. Rev.
Vortices with fractional flux in two-gap superconductors and in extended Faddeev model
We discuss vortices allowed in two-gap superconductors, bilayer systems and
in equivalent extended Faddeev model. We show that in these systems there exist
vortices which carry an arbitrary fraction of magnetic flux quantum. Besides
that we discuss topological defects which do not carry magnetic flux and
describe features of ordinary one-magnetic-flux-quantum vortices in the two-gap
system. The results should be relevant for the newly discovered two-band
superconductor .Comment: v2 references added, v3 journal version, presentation improved. Links
to related papers are available at the home page of the author
http://www.teorfys.uu.se/PEOPLE/ego
Metallic phase in stoichiometric CeOBiS 2 revealed by space-resolved ARPES
Recently CeOBiS2 system without any fluorine doping is found to show superconductivity posing question on its origin. Using space resolved ARPES we have found a metallic phase embedded in the morphological defects and at the sample edges of stoichiometric CeOBiS2. While bulk of the sample is semiconducting, the embedded metallic phase is characterized by the usual electron pocket at X point, similar to the Fermi surface of doped BiS2-based superconductors. Typical size of the observed metallic domain is larger than the superconducting correlation length of the system suggesting that the observed superconductivity in undoped CeOBiS2 might be due to this embedded metallic phase at the defects. The results also suggest a possible way to develop new systems by manipulation of the defects in these chalcogenides with structural instability
Determination of the local structure of SrMIrO (M = K, La) as a function of doping and temperature
The local structure of correlated spin-orbit insulator SrMIrO
(M = K, La) has been investigated by Ir L-edge extended x-ray absorption
fine structure measurements. The measurements were performed as a function of
temperature for different dopings induced by substitution of Sr with La or K.
It is found that Ir-O bonds have strong covalency and they hardly show any
change across the N\'eel temperature. In the studied doping range, neither Ir-O
bonds nor their dynamics, measured by their mean square relative displacements,
show any appreciable change upon carrier doping, indicating possibility of a
nanoscale phase separation in the doped system. On the other hand, there is a
large increase of the static disorder in Ir-Sr correlation, larger for K doping
than La doping. Similarities and differences with respect to the local lattice
displacements in cuprates are briefly discussed.Comment: Main text: 6 pages, 4 figures, Supplemental information: 2 pages, 2
figure
Linear response and collective oscillations in superconductors with d-wave pairing
Simple and physically transparent equations for the linear response of
layered superconductors with d-wave symmetry of the order parameter are derived
by means of the quasiclassic kinetic theory of superconductivity. Responses to
solenoidal and potential electric fields have different frequency dependencies.
The conductivity describing the response to the solenoidal field is limited by
the momentum relaxation, like in a normal metal. The response to the potential
electric field depends, in addition, on the branch imbalance relaxation rate.
The damping of plasma oscillations of superconducting electrons is determined
by dielectric relaxation and is small. Relaxation of branch imbalance
determined by elastic scattering is large enough to make the Carlson-Goldman
mode in d-wave superconductors overdamped.Comment: 11 pages, latex, no figures, submitted to Physical Review
Definitive experimental evidence for two-band superconductivity in MgB2
The superconducting gap of MgB2 has been studied by high-resolution
angle-resolved photoemission spectroscopy (ARPES). The momentum(k)-resolving
capability of ARPES enables us to identify the s- and p-orbital derived bands
predicted from band structure calculations and to successfully measure the
superconducting gap on each band. The results show that superconducting gaps
with values of 5.5 meV and 2.2 meV open on the s-band and the p-band,
respectively, but both the gaps close at the bulk transition temperature,
providing a definitive experimental evidence for the two-band superconductivity
in MgB2. The experiments validate the role of k-dependent electron-phonon
coupling as the origin of multiple-gap superconductivity in MgB2.Comment: PDF file onl
Guided Deep Decoder: Unsupervised Image Pair Fusion
The fusion of input and guidance images that have a tradeoff in their
information (e.g., hyperspectral and RGB image fusion or pansharpening) can be
interpreted as one general problem. However, previous studies applied a
task-specific handcrafted prior and did not address the problems with a unified
approach. To address this limitation, in this study, we propose a guided deep
decoder network as a general prior. The proposed network is composed of an
encoder-decoder network that exploits multi-scale features of a guidance image
and a deep decoder network that generates an output image. The two networks are
connected by feature refinement units to embed the multi-scale features of the
guidance image into the deep decoder network. The proposed network allows the
network parameters to be optimized in an unsupervised way without training
data. Our results show that the proposed network can achieve state-of-the-art
performance in various image fusion problems.Comment: ECCV 202
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