Dynamic polarizabilities and related properties of clock states of ytterbium atom

We carry out relativistic many-body calculations of the static and dynamic dipole polarizabilities of the ground 6s^2 ^1S_0 and the first excited $6s6p ^3P^o_0$ states of Yb. With these polarizabilities, we compute several properties of Yb relevant to optical lattice clocks operating on the 6s^2 ^1S_0 - 6s6p ^3P^o_0 transition. We determine (i) the first four {\em magic} wavelengths of the laser field for which the frequency of the clock transition is insensitive to the laser intensity. While the first magic wavelength is known, we predict the second, the third and the forth magic wavelengths to be 551 nm, 465 nm, and 413 nm. (ii) We reevaluate the effect of black-body radiation on the frequency of the clock transition, the resulting clock shift at $T=300 \mathrm{K}$ being $-1.41(17)$ Hz. (iii) We compute long-range interatomic van der Waals coefficients (in a.u.) C_6(6s^2 ^1S_0 +6s^2 ^1S_0) = 1909(160), C_6(6s^2 ^1S_0 + 6s6p ^3P_0) =2709(338) , and $C_6(6s6p ^3P_0 + 6s6p ^3P_0) =3886(360)$. Finally, we determine the atom-wall interaction coefficients (in a.u.), C_3 (6s^2 ^1S_0) =3.34 and $C_3 (6s6p ^3P_0) =3.68$. We also address and resolve a disagreement between previous calculations of the static polarizability of the ground state.Comment: 11 pages, 1 figur

A New Kind of Uniformly Accelerated Reference Frames

A new kind of uniformly accelerated reference frames with a line-element different from the M{\o}ller and Rindler ones is presented, in which every observer at $x, y, z=$consts. has the same constant acceleration. The laws of mechanics are checked in the new kind of frames. Its thermal property is studied. The comparison with the M{\o}ller and Rindler uniform accelerated reference frames is also made.Comment: 10 pages, 2 figures. to appear in Int. J. Mod. Phys.

Pre-K-Edge Structure on Anomalous X-Ray Scattering in LaMnO3

We study the pre-K-edge structure of the resonant X-ray scattering for forbidden reflections (anomalous scattering) in LaMnO3, using the band calculation based on the local density approximation. We find a two-peak structure with an intensity approximately 1/100 of that of the main peak. This originates from a mixing of 4p states of Mn to 3d states of neighboring Mn sites. The effect is enhanced by an interference with the tail of the main peak. The effect of the quadrupole transition is found to be one order of magnitude smaller than that of the dipole transition, modifying slightly the azimuthal-angle dependence.Comment: 4 pages, 5 figures, submitted to J. Phys. Soc. Jp

Separation of colour degree of freedom from dynamics in a soliton cellular automaton

We present an algorithm to reduce the coloured box-ball system, a one dimensional integrable cellular automaton described by motions of several colour (kind) of balls, into a simpler monochrome system. This algorithm extracts the colour degree of freedom of the automaton as a word which turns out to be a conserved quantity of this dynamical system. It is based on the theory of crystal basis and in particular on the tensor products of sl_n crystals of symmetric and anti-symmetric tensor representations.Comment: 19 page

Anomalous He-Gas High-Pressure Studies on Superconducting LaO1-xFxFeAs

AC susceptibility measurements have been carried out on superconducting LaO1-xFxFeAs for x=0.07 and 0.14 under He-gas pressures to about 0.8 GPa. Not only do the measured values of dTc/dP differ substantially from those obtained in previous studies using other pressure media, but the Tc(P) dependences observed depend on the detailed pressure/temperature history of the sample. A sizeable sensitivity of Tc(P) to shear stresses provides a possible explanation

Diverse Supernova Sources for the r-Process

(Abridged) It is shown that a semi-quantitative agreement with the gross solar r-process abundance pattern near and above mass number A=130 can be obtained by a superposition of two distinctive kinds of supernova r-process events. These correspond to a low frequency case L and a high frequency case H, which takes into account the low abundance of I129 and the high abundance of Hf182 in the early solar nebula. The lifetime of Hf182 associates the events in case H with the most common Type II supernovae. These events would be mainly responsible for the r-process nuclei near and above A=195. They would also make a significant amount of the nuclei between A=130 and 195, including Hf182, but very little I129. In order to match the solar r-process abundance pattern and to satisfy the I129 and Hf182 constraints, the events in case L, which would make the r-process nuclei near A=130 and the bulk of those between A=130 and 195, must occur 10 times less frequently but eject 10--20 times more r-process material in each event. We speculate that the usual neutron star remnants, and hence prolonged ejection of r-process material, are associated with the events in case L, whereas the more frequently occurring events in case H have ejection of other r-process material terminated by black hole formation during the neutrino cooling phase of the protoneutron star.Comment: 23 pages, AAS LATEX, 8 Postscript figure