Glass Dynamics at High Strain Rates

We present a shear-transformation-zone (STZ) theoretical analysis of molecular-dynamics simulations of a rapidly sheared metallic glass. These simulations are especially revealing because, although they are limited to high strain rates, they span temperatures ranging from well below to well above the glass transition. With one important discrepancy, the STZ theory reproduces the simulation data, including the way in which those data can be made to collapse onto simple curves by a scaling transformation. The STZ analysis implies that the system's behavior at high strain rates is controlled primarily by effective-temperature thermodynamics, as opposed to system-specific details of the molecular interactions. The discrepancy between theory and simulations occurs at the lower strain rates for temperatures near the glass transition. We argue that this discrepancy can be resolved by the same multi-species generalization of STZ theory that has been proposed recently for understanding frequency-dependent viscoelastic responses, Stokes-Einstein violations, and stretched-exponential relaxation in equilibrated glassy materials.Comment: 9 pages, 6 figure

Signatures of S-wave bound-state formation in finite volume

We discuss formation of an S-wave bound-state in finite volume on the basis of L\"uscher's phase-shift formula.It is found that although a bound-state pole condition is fulfilled only in the infinite volume limit, its modification by the finite size corrections is exponentially suppressed by the spatial extent $L$ in a finite box $L^3$. We also confirm that the appearance of the S-wave bound state is accompanied by an abrupt sign change of the S-wave scattering length even in finite volume through numerical simulations. This distinctive behavior may help us to discriminate the loosely bound state from the lowest energy level of the scattering state in finite volume simulations.Comment: 25 pages, 30 figures; v2: typos corrected and two references added, v3: final version to appear in PR

Laser spectroscopic studies of the pure rotational U_0(0) and W_0(0) transitions of solid parahydrogen

High resolution spectrum of multipole-induced transitions of solid parahydrogen was recorded using diode and difference frequency laser spectroscopy. The J=4<--0 pure rotational U_0(0) transition observed in the diode spectrum agrees well in frequency with the value reported by Balasubramanian et al. [Phys. Rev. Lett. 47, 1277 (1981)] but we observed a spectral width smaller by about a factor of 4. The J=6<--0 W_0(0) transition was observed to be exceedingly sharp, with a width of ~70 MHz, using a difference frequency spectrometer with tone-burst modulation. This transition is composed of three components with varying relative intensity depending upon the direction of polarization of laser radiation. These components were interpreted as the splitting of the M levels in the J=6 state due to crystal field interactions. In addition, a new broad feature was found at 2452.4 cm^(−1) in the low resolution Fourier-transform infrared (FTIR) spectrum of solid hydrogen and was assigned to be the phonon branch W_R(0) transition of the W_0(0) line. The selection rules, crystal field splitting of J=4 and J=6 rotons, and the measured linewidth based on these observations are discussed

A simple SO(10) GUT in five dimensions

A simple supersymmetric SO(10) GUT in five dimensions is considered. The fifth dimension is compactified on the $S^1/(Z_2\times Z_2^\prime)$ orbifold possessing two inequivalent fixed points. In our setup, all matter and Higgs multiplets reside on one brane (PS brane) where the original SO(10) gauge group is broken down to the Pati-Salam (PS) gauge group, SU(4)_c \timesSU(2)_L \times SU(2)$_R$, by the orbifold boundary condition, while only the SO(10) gauge multiplet resides in the bulk. The further breaking of the PS symmetry to the Standard Model gauge group is realized by Higgs multiplets on the PS brane as usual in four dimensional models. Proton decay is fully suppressed. In our simple setup, the gauge coupling unification is realized after incorporating threshold corrections of Kaluza-Klein modes. When supersymmetry is assumed to be broken on the other brane, supersymmetry breaking is transmitted to the PS brane through the gaugino mediation with the bulk gauge multiplet.Comment: 12 pages, 1 figure, some errors have been corrected (no change in conclusions

Gas, Iron and Gravitational Mass in Galaxy Clusters: The General Lack of Cluster Evolution at z < 1.0

We have analyzed the ASCA data of 29 nearby clusters of galaxies systematically, and obtained temperatures, iron abundances, and X-ray luminosities of their intracluster medium (ICM). We also estimate ICM mass using the beta model, and then evaluate iron mass contained in the ICM and derive the total gravitating mass. This gives the largest and most homogeneous information about the ICM derived only by the ASCA data. We compare these values with those of distant clusters whose temperatures, abundances, and luminosities were also measured with ASCA, and find no clear evidence of evolution for the clusters at z<1.0. Only the most distant cluster at z=1.0, AXJ2019.3+1127, has anomalously high iron abundance, but its iron mass in the ICM may be among normal values for the other clusters, because the ICM mass may be smaller than the other clusters. This may suggest a hint of evolution of clusters at z ~ 1.0.Comment: 23 pages including 5 figures. Using PASJ2.sty, and PASJ95.sty. Accepted by PAS