A new screening function for Coulomb renormalization

We introduce a new screening function which is useful for the few-body Coulomb scattering problem in ``screening and renormalization'' scheme. The new renormalization phase factor of the screening function is analytically shown. The Yukawa type of the screening potential has been used in several decades, we modify it to make more useful. As a concrete example, we compare the proton-proton scattering phase shifts calculated from these potentials. The numerical results document that high precision calculations of the renormalization are performed by the new screening function.Comment: 4 pages, 8 figure

Complex Energy Method for Scattering Processes

A method for solving few-body scattering equations is proposed and examined. The solution of the scattering equations at complex energies is analytically continued to get scattering T-matrix with real positive energy. Numerical examples document that the method works well for two-nucleon scattering and three-nucleon scattering, if the set of complex energies is properly chosen.Comment: 6 pages, no figures, resubmitted to Prog. Theor. Phy

Biquandles with structures related to virtual links and twisted links

We introduce two kinds of structures, called v-structures and t-structures, on biquandles. These structures are used for colorings of diagrams of virtual links and twisted links such that the numbers of colorings are invariants. Given a biquandle or a quandle, we give a method of constructing a biquandle with these structures. Using the numbers of colorings, we show that Bourgoin's twofoil and non-orientable virtual $m$-foils do not represent virtual links

Equivalent hyperon-nucleon interactions in low-momentum space

Equivalent interactions in a low-momentum space for the $\Lambda N$, $\Sigma N$ and $\Xi N$ interactions are calculated, using the SU$_6$ quark model potential as well as the Nijmegen OBEP model as the input bare interaction. Because the two-body scattering data has not been accumulated sufficiently to determine the hyperon-nucleon interactions unambiguously, the construction of the potential even in low-energy regions has to rely on a theoretical model. The equivalent interaction after removing high-momentum components is still model dependent. Because this model dependence reflects the character of the underlying potential model, it is instructive for better understanding of baryon-baryon interactions in the strangeness sector to study the low-momentum space $YN$ interactions.Comment: 9 pages, 13 figures, accepted for publication in Phys. Rev.

Separability of a Low-Momentum Effective Nucleon-Nucleon Potential

A realistic nucleon-nucleon potential is transformed into a low-momentum effective one (LMNN) using the Okubo theory. The separable potentials are converted from the LMNN with a universal separable expansion method and a simple Legendre expansion. Through the calculation of the triton binding energies, the separability for the convergence of these ranks is evaluated. It is found that there is a tendency for the lower momentum cutoff parameter $\Lambda$ of LMNN to gain good separability.Comment: 6 pages, 1 tabl

Complex Energy Method in 4-Body Faddeev-Yakubovsky Equations

The Complex Energy Method [Prog. Theor. Phys. {\bf 109}, 869L (2003)] is applied to the 4-body Faddeev-Yakubovsky equations in the 4-nucleon system. We obtain a well converged solution in all energy regions below and above the 4-nucleon break-up threshold.Comment: 4 pages (ReVTeX), 4 figures, Phys. Rev. C, in printin

Megabits secure key rate quantum key distribution

Quantum cryptography (QC) can provide unconditional secure communication between two authorized parties based on the basic principles of quantum mechanics. However, imperfect practical conditions limit its transmission distance and communication speed. Here we implemented the differential phase shift (DPS) quantum key distribution (QKD) with up-conversion assisted hybrid photon detector (HPD) and achieved 1.3 M bits per second secure key rate over a 10-km fiber, which is tolerant against the photon number splitting (PNS) attack, general collective attacks on individual photons, and any other known sequential unambiguous state discrimination (USD) attacks.Comment: 14 pages, 4 figure

Keynote Lecture: Recent Studies on Liquefaction Resistance of Sand-Effect of Saturation

The problem of sandy soils as to how they behave when they contain air or gas has been recently addressed in relation to evaluation of cyclic resistance during earthquakes. In order to shed some light on this issue, some laboratory tests were conducted on sand samples prepared in the triaxial test apparatus. The outcome of the tests disclosed that the degree of imperfect saturation can be quantified by way of the propagation velocity Vp of compressional wave or P-wave and that the cyclic resistance exhibits significant increase if the velocity Vp drops below 700 m/sec, a value smaller than the propagation velocity through water

The Galois Complexity of Graph Drawing: Why Numerical Solutions are Ubiquitous for Force-Directed, Spectral, and Circle Packing Drawings

Many well-known graph drawing techniques, including force directed drawings, spectral graph layouts, multidimensional scaling, and circle packings, have algebraic formulations. However, practical methods for producing such drawings ubiquitously use iterative numerical approximations rather than constructing and then solving algebraic expressions representing their exact solutions. To explain this phenomenon, we use Galois theory to show that many variants of these problems have solutions that cannot be expressed by nested radicals or nested roots of low-degree polynomials. Hence, such solutions cannot be computed exactly even in extended computational models that include such operations.Comment: Graph Drawing 201