17596274
Mesons with a Light Quark-Antiquark Pair and the Bethe-Salpeter Equation
The light quark-antiquark scattering Green's function is considered near a meson resonance peak. The Bethe-Salpeter equation is used to write formal expressions for the resonance width/mass ratio. Arguments are made concerning to what extent this ratio can be calculated perturbatively, and an upper bound is placed on the growth of this ratio as a function of radial excitation. Certain mesons and their radial excitations are considered, as well as the more general issue of classifying mesons in the quark model.
13972554
A non-perturbative analysis of symmetry breaking in two-dimensional φ4 theory using periodic field methods
Abstract We describe the generalization of spherical field theory to other modal expansion methods. The main approach remains the same, to reduce a d -dimensional field theory into a set of coupled one-dimensional systems. The method we discuss here uses an expansion with respect to periodic-box modes. We apply the method to φ 4 theory in two dimensions and compute the critical coupling and critical exponents. We compare with lattice results and predictions via universality and the two-dimensional Ising model.
118374917
Lattice calculations for A = 3 , 4, 6, 12 nuclei using chiral effective field theory
Abstract.We present lattice calculations for the ground-state energies of tritium, helium-3, helium-4, lithium-6, and carbon-12 nuclei. Our results were previously summarized in a letter publication. This paper provides full details of the calculations. We include isospin-breaking, Coulomb effects, and interactions up to next-to-next-to-leading order in chiral effective field theory.
15307965
The role of Monte Carlo within a diagonalization/Monte Carlo scheme
Abstract We review the method of stochastic error correction which eliminates the truncation error associated with any subspace diagonalization. Monte Carlo sampling is used to compute the contribution of the remaining basis vectors not included in the initial diagonalization. The method is part of a new approach to computational quantum physics which combines both diagonalization and Monte Carlo techniques.
118573105
Effective Field Theory for Bound State Reflection
Abstract Elastic quantum bound-state reflection from a hard-wall boundary provides direct information regarding the structure and compressibility of quantum bound states. We discuss elastic quantum bound-state reflection and derive a general theory for elastic reflection of shallow dimers from hard-wall surfaces using effective field theory. We show that there is a small expansion parameter for analytic calculations of the reflection scattering length. We present a calculation up to second order in the effective Hamiltonian in one, two, and three dimensions. We also provide numerical lattice results for all three cases as a comparison with our effective field theory results. Finally, we provide an analysis of the compressibility of the alpha particle confined to a cubic lattice with vanishing Dirichlet boundaries.
14276849
THE ROLE OF DIAGONALIZATION WITHIN A DIAGONALIZATION/MONTE CARLO SCHEME
We discuss a method called quasi-sparse eigenvector diagonalization which finds the most important basis vectors of the low energy eigenstates of a quantum Hamiltonian. It can operate using any basis, either orthogonal or non-orthogonal, and any sparse Hamiltonian, either Hermitian, non-Hermitian, finite-dimensional, or infinite-dimensional. The method is part of a new computational approach which combines both diagonalization and Monte Carlo techniques.
118591353
A prediction of the neutron and charged particle backgrounds in the L detector
Monte Carlo calculations have been made of the neutron flux and activation in the forward and barrel calorimeters in the L* detector and of the neutron flux in the central detector volume. In addition estimates of the charged particle and neutron background rates in the vicinity of the muon chambers has been determined. The Los Alamos National Laboratory code system LAHET and CINDER, 90 along with ISAJET and GEANT were used in these studies. The results indicate that neutron fluences as low as 2 {times} 10{sup 12} per SSC year can be achieved in the central volume. 6 refs., 3 figs., 2 tabs.
110046760
The readout and DAQ system of the L3 silicon microstrip detector
Abstract In 1993 the L3 detector at LEP has been equipped with a Silicon Microstrip Detector (SMD). In this paper we give a full description of the various components of the SMD readout and DAQ system.
110438896
Delay line readout of anode planes in proportional chambers
Abstract Simple delay lines have been developed for reading out active anode wire locations in multiwire proportional chambers. Anode wire positions are read out using commercial fast logic and time digitization apparatus with no special electronics required.
108442788
Experience with the SVX-H chip in the construction of the L3 Silicon Microvertex Detector
Abstract The SVX is a charge preamplifier with a sample and hold stage and sparse readout capability developed at the Lawrence Berkeley Laboratory. The SVX radiation hard version has been used by the SMD collaboration to build the L3 Silicon Microvertex Detector where double-sided AC coupled silicon sensors are read out. The SVX-H test procedure in the SMD detector assembly phase will be described as well as the obtained results.
121875662
Correlated neutron-deuteron and neutron-triton emission after pion capture on 12C
Abstract Energy and angle measurements of neutron-deuteron and neutron-triton pairs emitted following negative-pion capture on 12 C have been made. Strong 180° correlation is observed in the angular distributions of both types of pairs, indicating substantial absorption by clusters in the 12 C nucleus.