472 research outputs found
Pressure dependence of the superconducting critical temperature of HgBa2Ca2Cu3O9+y and HgBa2Ca3Cu4O10+y up to 3-0 Gpa.
Unconventional Charge Ordering in Na0.70CoO2 below 300 K
We present the results of measurements of the dc-magnetic susceptibility
chi(T) and the 23Na-NMR response of Na_{0.70}CoO_{2} at temperatures between 50
and 340 K. The chi(T) data suggest that for T > 75 K, the Co ions adopt an
effective configuration of Co^{3.4+}. The 23Na-NMR response reveals pronounced
anomalies near 250 and 295 K, but no evidence for magnetic phase transitions is
found in chi(T). Our data suggest the onset of a dramatic change in the Co
3d-electron spin dynamics at 295 K. This process is completed at 230 K. Our
results maybe interpreted as evidence for either a tendency to electron
localization or an unconventional charge-density wave phenomenon within the
cobalt oxide layer, CoO_2, 3d electron system near room temperature.Comment: 4 pages, 4 figures, re-submitted to Physical Review Letters. The
manuscript has been revised following the recommendations of the referees.
The discussion section contains substantial change
Crucial Physical Dependencies of the Core-Collapse Supernova Mechanism
We explore with self-consistent 2D F{\sc{ornax}} simulations the dependence
of the outcome of collapse on many-body corrections to neutrino-nucleon cross
sections, the nucleon-nucleon bremsstrahlung rate, electron capture on heavy
nuclei, pre-collapse seed perturbations, and inelastic neutrino-electron and
neutrino-nucleon scattering. Importantly, proximity to criticality amplifies
the role of even small changes in the neutrino-matter couplings, and such
changes can together add to produce outsized effects. When close to the
critical condition the cumulative result of a few small effects (including
seeds) that individually have only modest consequence can convert an anemic
into a robust explosion, or even a dud into a blast. Such sensitivity is not
seen in one dimension and may explain the apparent heterogeneity in the
outcomes of detailed simulations performed internationally. A natural
conclusion is that the different groups collectively are closer to a realistic
understanding of the mechanism of core-collapse supernovae than might have
seemed apparent.Comment: 25 pages; 10 figure
Magnetic Field Effects on Neutron Diffraction in the Antiferromagnetic Phase of
We discuss possible magnetic structures in UPt based on our analysis of
elastic neutron-scattering experiments in high magnetic fields at temperatures
. The existing experimental data can be explained by a single-{\bf q}
antiferromagnetic structure with three independent domains. For modest in-plane
spin-orbit interactions, the Zeeman coupling between the antiferromagnetic
order parameter and the magnetic field induces a rotation of the magnetic
moments, but not an adjustment of the propagation vector of the magnetic order.
A triple-{\bf q} magnetic structure is also consistent with neutron
experiments, but in general leads to a non-uniform magnetization in the
crystal. New experiments could decide between these structures.Comment: 5 figures included in the tex
Sorbents with immobilized glycopeptide antibiotics for separating optical isomers by high-performance liquid chromatography
Hindered E4 decay of the 12+ yrast trap in 52Fe
AbstractThe Îł decay of the 12+ yrast trap in 52Fe has been measured for the first time. The two E4 Îł-branches to the 8+ states are hindered with respect to other B(E4) reduced transition probabilities measured in the f7/2 shell. The interpretation of the data is given in the full pf shell model framework, comparing the results obtained with different residual interactions. It is shown that measurements of hexadecapole transition probabilities constitute a powerful tool in discriminating the correct configuration of the involved wavefunctions
Hindered E4 decay of the 12+ yrast trap in 52Fe
Abstract The Îł decay of the 12 + yrast trap in 52Fe has been measured for the first time. The two E4 Îł-branches to the 8 + states are hindered with respect to other B ( E 4 ) reduced transition probabilities measured in the f 7 / 2 shell. The interpretation of the data is given in the full pf shell model framework, comparing the results obtained with different residual interactions. It is shown that measurements of hexadecapole transition probabilities constitute a powerful tool in discriminating the correct configuration of the involved wavefunctions
Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV
A search for a Higgs boson decaying into two photons is described. The
analysis is performed using a dataset recorded by the CMS experiment at the LHC
from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an
integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross
section of the standard model Higgs boson decaying to two photons. The expected
exclusion limit at 95% confidence level is between 1.4 and 2.4 times the
standard model cross section in the mass range between 110 and 150 GeV. The
analysis of the data excludes, at 95% confidence level, the standard model
Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The
largest excess of events above the expected standard model background is
observed for a Higgs boson mass hypothesis of 124 GeV with a local significance
of 3.1 sigma. The global significance of observing an excess with a local
significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is
estimated to be 1.8 sigma. More data are required to ascertain the origin of
this excess.Comment: Submitted to Physics Letters
Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV
Results are presented from a search for a W' boson using a dataset
corresponding to 5.0 inverse femtobarns of integrated luminosity collected
during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV.
The W' boson is modeled as a heavy W boson, but different scenarios for the
couplings to fermions are considered, involving both left-handed and
right-handed chiral projections of the fermions, as well as an arbitrary
mixture of the two. The search is performed in the decay channel W' to t b,
leading to a final state signature with a single lepton (e, mu), missing
transverse energy, and jets, at least one of which is tagged as a b-jet. A W'
boson that couples to fermions with the same coupling constant as the W, but to
the right-handed rather than left-handed chiral projections, is excluded for
masses below 1.85 TeV at the 95% confidence level. For the first time using LHC
data, constraints on the W' gauge coupling for a set of left- and right-handed
coupling combinations have been placed. These results represent a significant
improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
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