730 research outputs found
Electronic States in Two-Dimensional Triangular Cobalt Oxides: Role of Electronic Correlation
We obtain the electronic states and structures of two-dimensional cobalt
oxides, NaCoO (x=0, 0.35, 0.5 and 0.75) by utilizing the
full-potential linear muffin-tin orbitals (FP-LMTO) methods, from which some
essential electronic interaction parameters are estimated: the bare on-site
Coulomb interaction of cobalt U=7.5 eV renormalizes to 5 eV for x=0.35,
the hybridizations t and t are -1.40 and 0.70 eV,
respectively. The density of states at E decreases from 6-7 states/eV in
the local density approximation (LDA) to about 1.0 states/eV in the LDA+U
scheme. The role of the intercalation of water molecules and the microscopic
mechanism of the superconductivity in NaCoOmHO is
discussed.Comment: minor errors correcte
Quantum-classical transition of the escape rate of uniaxial antiferromagnetic particles in an arbitrarily directed field
Quantum-classical escape rate transition has been studied for uniaxial
antiferromagnetic particles with an arbitrarily directed magnetic field. In the
case that the transverse and longitudinal fileds coexist, we calculate the
phase boundary line between first- and second-order transitions, from which
phase diagrams can be obtained. It is shown that the effects of the applied
longitudinal magnetic field on quantum-classical transition vary greatly for
different relative magnitudes of the non-compensation.Comment: to be appeared in Phys. Rev.
Pair Production of the Lightest Chargino via Gluon-Gluon Collisions
The production of the lightest chargino pair from gluon-gluon fusion is
studied in the minimal supersymmetric model(MSSM) at proton-proton colliders.
We find that with the chosen parameters, the production rate of the subprocess
can be over 2.7 femto barn when the chargino is higgsino-like, and the
corresponding total cross section in proton-proton collider can reach 56 femto
barn at the LHC in the CP-conserving MSSM. It shows that this loop mediated
subprocess can be competitive with the standard Drell-Yan subprocess in
proton-proton colliders, especially at the LHC. Furthermore, our calculation
shows it would be possible to extract information about some CP-violating phase
parameters, if we collected enough chargino pair events.Comment: 39 pages, LaTex, 8 figure
Clonal Tracking of Rhesus Macaque Hematopoiesis Highlights a Distinct Lineage Origin for Natural Killer Cells
SummaryAnalysis of hematopoietic stem cell function in nonhuman primates provides insights that are relevant for human biology and therapeutic strategies. In this study, we applied quantitative genetic barcoding to track the clonal output of transplanted autologous rhesus macaque hematopoietic stem and progenitor cells over a time period of up to 9.5 months. We found that unilineage short-term progenitors reconstituted myeloid and lymphoid lineages at 1 month but were supplanted over time by multilineage clones, initially myeloid restricted, then myeloid-B clones, and then stable myeloid-B-T multilineage, long-term repopulating clones. Surprisingly, reconstitution of the natural killer (NK) cell lineage, and particularly the major CD16+/CD56− peripheral blood NK compartment, showed limited clonal overlap with T, B, or myeloid lineages, and therefore appears to be ontologically distinct. Thus, in addition to providing insights into clonal behavior over time, our analysis suggests an unexpected paradigm for the relationship between NK cells and other hematopoietic lineages in primates
Modified f(G) gravity models with curvature-matter coupling
A modified f(G) gravity model with coupling between matter and geometry is
proposed, which is described by the product of the Lagrange density of the
matter and an arbitrary function of the Gauss-Bonnet term. The field equations
and the equations of motion corresponding to this model show the
non-conservation of the energy-momentum tensor, the presence of an extra-force
acting on test particles and the non-geodesic motion. Moreover, the energy
conditions and the stability criterion at de Sitter point in the modified f(G)
gravity models with curvature-matter coupling are derived, which can degenerate
to the well-known energy conditions in general relativity. Furthermore, in
order to get some insight on the meaning of these energy conditions, we apply
them to the specific models of f(G) gravity and the corresponding constraints
on the models are given. In addition, the conditions and the candidate for
late-time cosmic accelerated expansion in the modified f(G) gravity are studied
by means of conditions of power-law expansion and the equation of state of
matter less than -1/ 3 .Comment: 13 pages, 4 figure
Superdeformed rotational bands in the Mercury region; A Cranked Skyrme-Hartree-Fock-Bogoliubov study
A study of rotational properties of the ground superdeformed bands in \Hg{0},
\Hg{2}, \Hg{4}, and \Pb{4} is presented. We use the cranked
Hartree-Fock-Bogoliubov method with the {\skm} parametrization of the Skyrme
force in the particle-hole channel and a seniority interaction in the pairing
channel. An approximate particle number projection is performed by means of the
Lipkin-Nogami prescription. We analyze the proton and neutron quasiparticle
routhians in connection with the present information on about thirty presently
observed superdeformed bands in nuclei close neighbours of \Hg{2}.Comment: 26 LaTeX pages, 14 uuencoded postscript figures included, Preprint
IPN-TH 93-6
Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set
We report a measurement of the bottom-strange meson mixing phase \beta_s
using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays
in which the quark-flavor content of the bottom-strange meson is identified at
production. This measurement uses the full data set of proton-antiproton
collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment
at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity.
We report confidence regions in the two-dimensional space of \beta_s and the
B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2,
-1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in
agreement with the standard model expectation. Assuming the standard model
value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +-
0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +-
0.009 (syst) ps, which are consistent and competitive with determinations by
other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012
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
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