2,008 research outputs found
Charmed scalar resonances -- Conventional and four-quark mesons
We propose that there coexist two scalar mesons of different structures (a
conventional meson and a four-quark meson) in the recently observed broad bumps
just below the large peak of the tensor meson in the D-pi mass distribution. We
base this proposal on the interpretation of the charm-strange scalar meson of
mass 2317 MeV as a four-quark meson. The strange counterparts of these scalar
mesons are also studied.Comment: 4 pages, 0 figures, Revte
Onset of T=0 Pairing and Deformations in High Spin States of the N=Z Nucleus 48Cr
The yrast line of the N=Z nucleus 48Cr is studied up to high spins by means
of the cranked Hartree-Fock-Bogoliubov method including the T=0 and T=1 isospin
pairing channels. A Skyrme force is used in the mean-field channel together
with a zero-range density-dependent interaction in the pairing channels. The
extensions of the method needed to incorporate the neutron-proton pairing are
summarized. The T=0 pairing correlations are found to play a decisive role for
deformation properties and excitation energies above 16hbar which is the
maximum spin that can be obtained in the f7/2 subshell.Comment: LaTeX, 4 ps figure
Superdeformed Bands of Odd Nuclei in A=190 Region in the Quasiparticle Picture
We study the properties of the superdeformed (SD) bands of 195Pb and 193Hg by
the cranked Hartree-Fock-Bogoliubov method. Our calculations reproduce the flat
behavior of the dynamical moment of inertia of two of the SD bands of 195Pb
measured recently. We discuss possible configuration assignments for the
observed bands 3 and 4 of 195Pb. We also calculate the two interacting SD bands
of 193Hg. Our analysis confirms the superiority of a density-dependent pairing
force over a seniority pairing interaction.Comment: 12 pages, 5 Postscript figures, submitted to Phys.Rev.
Magnetic and transport properties of the spin-state disordered oxide La0.8Sr0.2Co_{1-x}Rh_xO_{3-\delta}
We report measurements and analysis of magnetization, resistivity and
thermopower of polycrystalline samples of the perovskite-type Co/Rh oxide
LaSrCoRhO. This system constitutes a
solid solution for a full range of ,in which the crystal structure changes
from rhombohedral to orthorhombic symmetry with increasing Rh content . The
magnetization data reveal that the magnetic ground state immediately changes
upon Rh substitution from ferromagnetic to paramagnetic with increasing
near 0.25, which is close to the structural phase boundary. We find that one
substituted Rh ion diminishes the saturation moment by 9 , which implies
that one Rh ion makes a few magnetic Co ions nonmagnetic (the low
spin state), and causes disorder in the spin state and the highest occupied
orbital. In this disordered composition (), we find that
the thermopower is anomalously enhanced below 50 K. In particular, the
thermopower of =0.5 is larger by a factor of 10 than those of =0 and 1,
and the temperature coefficient reaches 4 V/K which is as large as
that of heavy-fermion materials such as CeRuSi.Comment: 8 pages, 6 figures, accepted to Phys. Rev.
Thermal conductivity of the thermoelectric layered cobalt oxides measured by the Harman method
In-plane thermal conductivity of the thermoelectric layered cobalt oxides has
been measured using the Harman method, in which thermal conductivity is
obtained from temperature gradient induced by applied current. We have found
that the charge reservoir block (the block other than the CoO block)
dominates the thermal conduction, where a nano-block integration concept is
effective for material design. We have further found that the thermal
conductivity shows a small but finite in-plane anisotropy between and
axes, which can be ascribed to the misfit structure.Comment: 4 pages, 4 figures, J. Appl. Phys. (scheduled on July 1, 2004
An Electronic Model for layer based systems: Chiral RVB metal and Superconductivity
Takada et al. have reported superconductivity in layered Na__x CoO_2.yH_2O
() and more recently Wen et al. in ()(\tc). We model a reference neutral \cob layer as an
orbitally non-degenerate spin-\half antiferromagnetic Mott insulator on a
triangular lattice and Na__x CoO_2.yH_2O and as electron
doped Mott insulators described by a t-J model. It is suggested that at optimal
doping chiral spin fluctuations enhanced by the dopant dynamics leads to a
d-wave superconducting state. A chiral RVB metal, a PT violating state with
condensed RVB gauge fields, with a possible weak ferromagnetism and low
temperature p-wave superconductivity are also suggested at higher dopings.Comment: 4 pages of LaTex file, 6 figures in eps files. Typos and minor
corrections mad
Non-factorizable long distance contributions in color suppressed decays of B mesons
, , and decays are
studied. Their amplitude is given by a sum of factorized and non-factorizable
ones. The latter which is estimated by using a hard pion approximation is
rather small in color favored and decays but still
can efficiently interfere with the main amplitude given by the factorization.
In the color suppressed and decays, the
non-factorizable contribution is very important. The sum of the factorized and
non-factorizable amplitudes can reproduce well the existing experimental data
on the branching ratios for the color favored and
and the color suppressed and decays by
taking reasonable values of unknown parameters involved.Comment: 19 pages, Revte
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