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 La$_{0.8}$Sr$_{0.2}$Co$_{1-x}$Rh$_x$O$_{3-\delta}$. This system constitutes a solid solution for a full range of $x$,in which the crystal structure changes from rhombohedral to orthorhombic symmetry with increasing Rh content $x$. The magnetization data reveal that the magnetic ground state immediately changes upon Rh substitution from ferromagnetic to paramagnetic with increasing $x$ near 0.25, which is close to the structural phase boundary. We find that one substituted Rh ion diminishes the saturation moment by 9 $\mu_B$, which implies that one Rh$^{3+}$ ion makes a few magnetic Co$^{3+}$ ions nonmagnetic (the low spin state), and causes disorder in the spin state and the highest occupied orbital. In this disordered composition ($0.05\le x \le 0.75$), we find that the thermopower is anomalously enhanced below 50 K. In particular, the thermopower of $x$=0.5 is larger by a factor of 10 than those of $x$=0 and 1, and the temperature coefficient reaches 4 $\mu$V/K$^2$ which is as large as that of heavy-fermion materials such as CeRu$_2$Si$_2$.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$_2$ 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 $a$ and $b$ 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 CoO2CoO_2 layer based systems: Chiral RVB metal and Superconductivity

Takada et al. have reported superconductivity in layered Na__x CoO_2.yH_2O ($T_c \approx5 K$) and more recently Wen et al. in $A_xCoO_{2+\delta}$ ($A = Na,K$)(\tc$\approx~31 K$). 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 $A_xCoO_{2+\delta}$ 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

$\bar B \to D\pi$, $D^*\pi$, $J/\psi\bar K$ and $J/\psi\pi$ 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 $\bar B \to D\pi$ and $D^*\pi$ decays but still can efficiently interfere with the main amplitude given by the factorization. In the color suppressed $\bar B \to J/\psi\bar K$ and $J/\psi\pi$ 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 $\bar B \to D\pi$ and $D^*\pi$ and the color suppressed $\bar B \to J/\psi \bar K$ and $J/\psi\pi$ decays by taking reasonable values of unknown parameters involved.Comment: 19 pages, Revte