Enhanced mass transfer during dwarf nova outbursts by irradiation of the secondary?

One of the remaining issues in the problems of dwarf novae is whether or not enhanced mass transfer due to irradiation of the secondary stars could occur during outbursts. In a previous paper (Osaki and Meyer 2003), we presented a theoretical analysis that shows no appreciable enhancement of the mass outflow rate. This conclusion is challenged by Smak (2004) who claims that equations used in our analysis were incorrect and that in systems with short orbital periods substantial enhancement could occur. In this letter, we examine the origin of such divergent conclusions. We show that Smak's solutions are unacceptable from the standpoint of the equation of continuity and that our analysis is an appropriate one to treat this problem.Comment: 4 pages, accepted by Astronomy &.Astrophysics Letter

A Large-scale CO Imaging of the Galactic Center. II. Dynamical Properties of Molecular Clouds

The data from the Nobeyama Radio Observatory 45 m telescope Galactic Center CO survey have been analyzed to generate a compilation of molecular clouds with intense CO emission in this region. Clouds are identified in an automated manner throughout the main part of the survey data for all CO emission peaks exceeding 10 K ($T_R^*$). Correlations between the size, velocity dispersion, virial mass, and the CO luminosity, for the molecular clouds in the Galactic center were shown. We diagnosed gravitational stabilities of identified clouds assuming that the disk clouds are nearly at the onset of gravitational instability. Most of the clouds and cloud complexes in the Galactic center are gravitationally stable, while some clouds with intense CO emission are gravitationally unstable.Comment: 4 pages, 4 figures, to appear in the Proceedings of the 32nd COSPAR Scientific Assembl

Prediction of Pore Water Pressure During Earthquakes in Southern Kyoto Area

This paper is concerned with the liquefaction analysis for the hypothetical earthquake in southern Kyoto area in Japan. The method of liquefaction analysis can consider the local soil properties of sand and clay, using the constitutive equations of clay and sand, and the theory of mixture. From this study, it becomes evident that liquefaction will occur at the site near the river, and also liquefaction can be observed in the clay layers

Are the anti-charmed and bottomed pentaquarks molecular heptaquarks?

I study the charmed $uudd\bar c$ resonance D*p (3100) very recently discovered by the H1 collaboration at Hera. An anticharmed resonance was already predicted, in a recent publication mostly dedicated to the S=1 resonance Theta+(1540). To confirm these recent predictions, I apply the same standard quark model with a quark-antiquark annihilation constrained by chiral symmetry. I find that repulsion excludes the D*p (3100) as a $uudd\bar c$ s-wave pentaquark. I explore the D*p (3100) as a heptaquark, equivalent to a N-pi-D* linear molecule, with positive parity and total isospin I=0. I find that the N-D repulsion is cancelled by the attraction existing in the N-pi and pi-D channels. In our framework this state is harder to bind than the Theta+ described by a k-pi-N borromean bound-state, a lower binding energy is expected in agreement with the H1 observation. Multiquark molecules N-pi-D, N-pi-B* and N-pi-B are also predicted.Comment: 5 pages, 2 figures, RevTe

Kaon-nucleon interaction in the extended chiral SU(3) quark model

The chiral SU(3) quark model is extended to include the coupling between the quark and vector chiral fields. The one-gluon exchange (OGE) which dominantly governs the short-range quark-quark interaction in the original chiral SU(3) quark model is now nearly replaced by the vector-meson exchange. Using this model, the isospin I=0 and I=1 kaon-nucleon S, P, D, F wave phase shifts are dynamically studied by solving the resonating group method (RGM) equation. Similar to those given by the original chiral SU(3) quark model, the calculated results for many partial waves are consistent with the experiment, while there is no improvement in this new approach for the P_{13} and D_{15} channels, of which the theoretical phase shifts are too much repulsive and attractive respectively when the laboratory momentum of the kaon meson is greater than 300 MeV.Comment: 19 pages, 16 figures. Accepted by Phys. Rev.

Anisotropic Lattice QCD Studies of Penta-quark Anti-decuplet

Anti-decuplet penta-quark baryon is studied with the quenched anisotropic lattice QCD for accurate measurement of the correlator. Both the positive and negative parity states are studied using a non-NK type interpolating field with I=0 and J=1/2. After the chiral extrapolation, the lowest positive parity state is found at m_{Theta} \simeq 2.25 GeV, which is too massive to be identified with the experimentally observed Theta^+(1540). The lowest negative parity state is found at m_{Theta}\simeq 1.75 GeV, which is rather close to the empirical value. To confirm that this state is a compact 5Q resonance, a new method with ``hybrid boundary condition (HBC)'' is proposed. The HBC analysis shows that the observed state in the negative parity channel is an NK scattering state.Comment: A talk given at International Workshop PENTAQUARK04, July 20-23, 2004 at SPring-8, Japan, 8 pages, 7 figures, 2 table

Constitutive Equations for Sands and Overconsolidated Clays under Dynamic Loads Based on Elasto-Plasticity

This paper is concerned with the constitutive equations of the sands and overconsolidated clays under cyclic loads. The constitutive equations are derived, based on the theory of plasticity and real stress-strain behavior of soils, The non-associated flow rule is applied to the derivation of the equations. The derived equations can explain the mechanical behavior of overconsolidated clays and sands under cyclic stresses and have nine soil parameters, and are applicable to liquefaction analysis

Liquefaction Analysis of Sand Deposits Based on Cyclic Elasto-Piasticity

The one-dimentional liquefaction analysis of sand deposits is performed by using the theory of two-phase mixture and the elasto-plastic constitutive equations of sand that can describe the dynamic dilatancy effect of soil under cyclic loading. The analytical results obtained by finite difference method explain well the dynamic behavior of sand deposits including liquefaction phenomena. Especially, the stress path which is particular to liquefaction is presented by considering a horizontally confined condition

A Consistent Study of the the Low Energy Baryon Spectrum and the Nucleon-Nucleon Interaction within the Chiral Quark Model

By solving the Schr\"{o}dinger equation for the three-quark system in the hyperspherical harmonic approach, we have studied the low energy part of the nucleon and $\Delta$ spectra using a quark-quark interaction which reproduces the nucleon-nucleon phenomenology. The quark-quark hamiltonian considered includes, besides the usual one-gluon exchange, pion and sigma exchanges generated by the chiral symmetry breaking. The baryonic spectrum obtained is reasonable and the resulting wave function gives consistency to the ansatz used in the two baryon system.Comment: Accepted for publication in Phys. Lett.

Parametric resonance at the critical temperature in high energy heavy ion collisions

Parametric resonance in soft modes at the critical temperature ($T_{c}$) in high energy heavy ion collisions is studied in the case when the temperature ($T$) of the system is almost constant for a long time. By deviding the fields into three parts, zero mode (condensate), soft modes and hard modes and assuming that the hard modes are in thermal equilibrium, we derive the equation of motion for soft modes at $T=T_{c}$. Enhanced modes are extracted by comparing with the Mathieu equation for the condensate oscillating along the sigma axis at $T=T_{c}$. It is found that the soft mode of $\pi$ fields at about 174 MeV is enhanced.Comment: 8 pages, 1 figure Some statements and equations are modified to clarif