Beyond Fermi pseudopotential: a modified GP equation

We present an effective potential and the corresponding modified Gross-Pitaevskii equation that account for the energy dependence of the two-body scattering amplitude through an effective-range expansion. For the ground state energy of a trapped condensate, the theory leads to what we call a shape-dependent confinement correction that improves agreements with diffusion Monte Carlo calculations. The theory illustrates, for relatively strong confinement and/or high density, how the shape dependence on atom-atom interaction can come into play in a many-atom quantum system.Comment: 8 pages, 5 figure

Performance of bolted steel-beam to CFST-column joints using stiffened angles in column-removal scenario

This paper presents three experimental investigations on the performance of steel-beam to CFST-column joints using stiffened angle, long bolts and fin plate under a middle column removal scenario. Three specimens were designed and tested. The failure modes and catenary action are investigated in detail. The test results show that increasing the angle plate thickness at the joint could not only improve its performance significantly, but also trigger an early formation of catenary action. Increasing the length of short-limb had influence on the deformation ability of the proposed joint, rather than the load capacity. The buckling of stiffeners could prevent the brittle failure of the joints. With the contribution of catenary action, the joint shows much higher rotation capacities than that required in DoD design guidance. The initial stiffness of the joint was calculated using an analytical model with consideration of bolt pretension. Good agreement to the test results is achieved. A numerical analysis is also carried out, whose results show that adding additional row of bolts would improve the redundancy of the joint under column loss. An equivalent dynamic response evaluation of the joints was also performed. The results show that dynamic amplification coefficient should be worked out considering catenary action under large deformation

Flat band electrons and interactions in rhombohedral trilayer graphene

Multilayer graphene systems with a rhombohedral stacking order harbor nearly flat bands in their single-particle spectrum. We propose ansatz states to describe the surface-localized states of flat band electrons. The absence of kinetic dispersion near the fermi level leaves the interaction as a dominate mechanism to govern the low energy physics of a low density electron system. We build up an effective lattice model in two interacting low-energy bands, where the full terms of the Coulomb interaction, including those long-range and off-diagonal parts, have been considered. The interaction matrix coefficients in the many-body Hamiltonian model are directly calculated for a trilayer system using orthonormal Wannier basis. We then present a flat-band projection to yield an interaction-only lattice model for flat band electrons. We find that this limited model might energetically favor a ferromagnetic quantum crystal under certain conditions.Comment: 8 pages, 3 figures, 3 tables. add journal reference and some discussions in the context. arXiv admin note: text overlap with arXiv:1108.008

t-c gamma and t-cg in warped extra dimensions

In this work, we calculate the top quark rare decays t-cgamma and t-cg in the framework where the standard model is embedded in a warped extra dimension with the custodial symmetry SU(3)c*SU(2)L*SU(2)R*U(1)x*PLR. Adopting reasonable assumptions on the parameter space,we numerically find the branching ratios of t-cgamma exceeding 10^-6 and that of t-cg exceeding 10^-5 respectively, which can be detected in near future.Comment: arXiv admin note: text overlap with arXiv:0903.2415 by other author

Energy dependent chemical potentials of light particles and quarks from yield ratios of antiparticles to particles in high energy collisions

We collect the yields of charged pions ($\pi^-$ and $\pi^+$), charged kaons ($K^-$ and $K^+$), anti-protons ($\bar p$), and protons ($p$) produced in mid-rapidity interval (in most cases) in central gold-gold (Au-Au), central lead-lead (Pb-Pb), and inelastic or non-single-diffractive proton-proton ($pp$) collisions at different collision energies. The chemical potentials of light particles and quarks are extracted from the yield ratios, $\pi^-/\pi^+$, $K^-/K^+$, and $\bar p/p$, of antiparticles to particles over an energy range from a few GeV to above 10 TeV. At a few GeV ($\sim4$ GeV), the chemical potentials show, and the yield ratios do not show, different trends comparing with those at other energies, though the limiting values of the chemical potentials and the yield ratios at very high energy are 0 and 1 respectively.Comment: 10 pages, 3 figures. Universe, accepte