Semiclassical ordering in the large-N pyrochlore antiferromagnet

We study the semiclassical limit of the Sp(N) generalization of the pyrochlore lattice Heisenberg antiferromagnet by expanding about the N --> infinity saddlepoint in powers of a generalized inverse spin. To leading order, we write down an effective Hamiltonian as a series in loops on the lattice. Using this as a formula for calculating the energy of any classical ground state, we perform Monte Carlo simulations and find a unique collinear ground state. This state is not a ground state of linear spin-wave theory, and can therefore not be a physical (N = 1) semiclassical ground state.     

Meson-nucleon coupling constants in a quark model

An effective vector exchange in a quark model, previously used for nucleon-antinucleon annihilation and meson decays, is applied to nucleon-meson and decuplet baryon-meson couplings. A reasonable fit to experimental data is obtained.This article is written in honour and memory of Michael Moravcsik. He was both a dedicated physicist and a very humane person with wide interests in the world around him. One of us (EMH) knew him well and will continue to cherish his friendship     

Engineering the plasmon resonance of large area bimetallic nanoparticle films by laser nanostructuring for chemical sensors

Large area fabrication of metal alloy nanoparticles with tunable surface plasmon resonances on low-cost substrates is reported. A UV excimer laser was used to anneal 5 nm thick Ag Au bilayer films deposited with different composition ratios to create alloy nanoparticles. These engineered surfaces are used to investigate how the wavelength of the surface plasmon resonance affects the optical detection capability of chemical species by surface-enhanced Raman spectroscopy.     

Parity violation: Radiative pion capture in hydrogen

We investigate radiative pion capture in hydrogen, π^? → nγ, as a means of determining the parity-violating πNN coupling constant ?_π. We include contributions from the lightest baryon resonance [Δ(1232)] and the light vector mesons [ρ, ω, φ]. Our results indicate that, despite their negligible role in parity-conserving amplitudes, the effects of the Δ and ρ may hamper the determination of ?_π.     

Classical many-body model for heavy-ion collisions incorporating the Pauli principle

A classical model for heavy-ion collisions, introduced previously, has been extended to include certain effects of the Pauli principle. All nucleons are treated equally. They obey classical dynamics and interact through an ordinary two-body force and through a momentumdependent two-body “Pauli core” which satisfies, approximately, that $\text{p}{}_{\mathrm{ij}}\text{r}{}_{\mathrm{ij}}\text{≧ξ}\text{h}\text{?}$, where ξ is a dimensionless constant. A form for the Pauli core is presented. The ordinary two-body force has been adjusted to fit bulk properties of nuclei and to reproduce that moment of nucleon nucleon scattering cross sections which is relevant to hydrodynamics. The parameters of the forces are given.     

Parity violation in electron-deuteron scattering I. Methodology and elastic scattering

In this paper, we present methodology for investigating theoretically parity violation in both the elastic and break-up channels of electron-deuteron scattering, restricting ourselves to energies in which non-relativistic expansions are allowed for nucleons. The deficiency in the standard impulse approximation related to gauge invariance is remedied by relating it to the “elementary-particle” treatment. Results for parity violation in elastic electrondeuteron scattering are presented and discussed.