The Lyman <span class='mathrm'>α</span> and Lyman <span class='mathrm'>β</span> lines in solar coronal streamers

No abstract available

NΩN\Omega and ΔΩ\Delta\Omega dibaryons in SU(3) chiral quark model

The binding energy of the six quark system with strangeness s=-3 is investigated under the chiral SU(3) constituent quark model in the framework of $RGM$. The calculations of the single $N\Omega$ channel with spin S=2 and the single $\Delta\Omega$ channel with spin S=3 are performed. The results show that both systems could be dibaryons and the interaction induced by the chiral field plays a very important role on forming bound states in the systems considered. The phase shifts and scattering lengths in corresponding channels are also given.Comment: LaTex file with 5 figure

The substructure and halo population of the Double Cluster hh and χ\chi Persei

In order to study the stellar population and possible substructures in the outskirts of Double Cluster $h$ and $\chi$ Persei, we investigate using the GAIA DR2 data a sky area of about 7.5 degrees in radius around the Double Cluster cores. We identify member stars using various criteria, including their kinematics (viz, proper motion), individual parallaxes, as well as photometric properties. A total of 2186 member stars in the parameter space were identified as members. Based on the spatial distribution of the member stars, we find an extended halo structure of $h$ and $\chi$ Persei, about 6 - 8 times larger than their core radii. We report the discovery of filamentary substructures extending to about 200 pc away from the Double Cluster. The tangential velocities of these distant substructures suggest that they are more likely to be the remnants of primordial structures, instead of a tidally disrupted stream from the cluster cores. Moreover, the internal kinematic analysis indicates that halo stars seems to be experiencing a dynamic stretching in the RA direction, while the impact of the core components is relatively negligible. This work also suggests that the physical scale and internal motions of young massive star clusters may be more complex than previously thought.Comment: 9 pagges, 9 figures, Accecpted to A&

Particle Spectrum of the Supersymmetric Standard Model from the Massless Excitations of a Four Dimensional Superstring

A superstring action is quantised with Neveu Schwarz(NS) and Ramond(R) boundary conditions. The zero mass states of the NS sector are classified as the vector gluons, W-mesons, $B_{\mu}$-mesons and scalars containing Higgs. The fifteen zero mass fermions are obtained from the Ramond sector. A space time supersymmetric Hamiltonian of the Standard Model is presented without any conventional SUSY particles

Evidence for universality in the initial planetesimal mass function

Planetesimals may form from the gravitational collapse of dense particle clumps initiated by the streaming instability. We use simulations of aerodynamically coupled gas-particle mixtures to investigate whether the properties of planetesimals formed in this way depend upon the sizes of the particles that participate in the instability. Based on three high resolution simulations that span a range of dimensionless stopping time $6 \times 10^{-3} \leq \tau \leq 2$ no statistically significant differences in the initial planetesimal mass function are found. The mass functions are fit by a power-law, ${\rm d}N / {\rm d}M_p \propto M_p^{-p}$, with $p=1.5-1.7$ and errors of $\Delta p \approx 0.1$. Comparing the particle density fields prior to collapse, we find that the high wavenumber power spectra are similarly indistinguishable, though the large-scale geometry of structures induced via the streaming instability is significantly different between all three cases. We interpret the results as evidence for a near-universal slope to the mass function, arising from the small-scale structure of streaming-induced turbulence.Comment: 7 pages, 4 figures, accepted to ApJ Letters after minor modifications, including two new figures and some new text that better clarify our result

Temperature dependence of thermal conductivity in 1D nonlinear lattices

We examine the temperature dependence of thermal conductivity of one dimensional nonlinear (anharmonic) lattices with and without on-site potential. It is found from computer simulation that the heat conductivity depends on temperature via the strength of nonlinearity. Based on this correlation, we make a conjecture in the effective phonon theory that the mean-free-path of the effective phonon is inversely proportional to the strength of nonlinearity. We demonstrate analytically and numerically that the temperature behavior of the heat conductivity $\kappa\propto1/T$ is not universal for 1D harmonic lattices with a small nonlinear perturbation. The computer simulations of temperature dependence of heat conductivity in general 1D nonlinear lattices are in good agreements with our theoretic predictions. Possible experimental test is discussed.Comment: 6 pages and 2 figures. Accepted for publication in Europhys. Let

Thermal transistor: Heat flux switching and modulating

Thermal transistor is an efficient heat control device which can act as a heat switch as well as a heat modulator. In this paper, we study systematically one-dimensional and two-dimensional thermal transistors. In particular, we show how to improve significantly the efficiency of the one-dimensional thermal transistor. The study is also extended to the design of two-dimensional thermal transistor by coupling different anharmonic lattices such as the Frenkel-Kontorova and the Fermi-Pasta-Ulam lattices. Analogy between anharmonic lattices and single-walled carbon nanotube is drawn and possible experimental realization with multi-walled nanotube is suggested.Comment: To appear in J. Phys. Soc. Jp

The Radiative Decay of Vector Mesons

In this paper, radiative decays $\rho^0 \to \pi^+\pi^-\gamma, \pi^0\pi^0\gamma$ ,$\phi \to K^+K^-\gamma, K^0 \bar{K^0}\gamma$ are studied systematically in the U(3)_L\timesU(3)_R chiral theory of mesons. The theoretical differential spectrum with respect to photon energy and branch ratio for $\rho^0 \to \pi^+\pi^-\gamma$ agree well with the experimental data. Differential spectrums and branch ratios for $\rho^0 \to \pi^0\pi^0\gamma, \phi \to K^+ K^-\gamma,\phi \to K^0\bar{K^0}\gamma$ are predicted. The process $\phi \to K^0 \bar{K^0} \gamma$ is relevant to precision measurment of CP-violation parameters in the kaon systerm at a $\phi$-factory. We give a complete estimate of the branch ratio for this decay process by including scalar resonance $f_0, a_0$ poles, nonresonant smooth amplitude and an abnormal parity process with $K^*$ pole which hasn't been considered before. We conclude that processes with intermediate $K^*$ do not pose a potential background problem for $\phi\to K^0\bar{K}^0$ CP violation experiments.Comment: Revtex file, 12 pages, 9 eps figure

Generalized Dynamic Scaling for Critical Relaxations

The dynamic relaxation process for the two dimensional Potts model at criticality starting from an initial state with very high temperature and arbitrary magnetization is investigated with Monte Carlo methods. The results show that there exists universal scaling behaviour even in the short-time regime of the dynamic evolution. In order to describe the dependence of the scaling behaviour on the initial magnetization, a critical characteristic function is introduced.Comment: Latex, 8 pages, 3 figures, to appear in Phys. Rev. Let