Meson Decay Constants from the Valence Approximation to Lattice QCD

We evaluate $f_{\pi}/ m_{\rho}$, $f_K/ m_{\rho}$, $1/f_{\rho}$, and $m_{\phi}/(f_{\phi} m_{\rho})$, extrapolated to physical quark mass, zero lattice spacing and infinite volume, for lattice QCD with Wilson quarks in the valence (quenched) approximation. The predicted ratios differ from experiment by amounts ranging from 12\% to 17\% equivalent to between 0.9 and 2.8 times the corresponding statistical uncertainties.Comment: uufiles encoded copy of 40 page Latex article, including 14 figures in Postscript. The long version of hep-lat/9302012, IBM/HET 93-

The Spectrum from Lattice NRQCD

I review recent results for heavy-heavy spectroscopy using Lattice NRQCD. The NRQCD collaboration reports that spin-independent splittings for the $\Upsilon$ are scaling for a sensible range of $\beta$ values in the quenched approximation. Spin-dependent splittings are not, if the scale is set by spin-independent splittings. Results which include higher order spin-dependent relativistic and discretisation corrections show differences from previous (NRQCD collaboration) results without these. As expected, the differences are small for $\Upsilon$ but rather large for charmonium. New results from the SESAM collaboration for $\Upsilon$ spectroscopy on configurations with Wilson dynamical fermions show good agreement with previous results on HEMCGC configurations with staggered dynamical fermions.Comment: 10 pages, Latex. 10 figures, 7 in postscript. Review for Tsukuba worksho

Delta Baryon Magnetic Moments From Lattice QCD

Theoretical predictions for the magnetic moments of the physical Delta baryons are extracted from lattice QCD calculations. We utilize finite-range regulated effective field theory that is constructed to have the correct Dirac moment mass dependence in the region where the up and down quark masses are heavy. Of particular interest is the chiral nonanalytic behaviour encountered as the nucleon-pion decay channel opens. We find a Delta^++ magnetic moment (at the Delta pole) of 4.99 \pm 0.56 \mu_N. This result is within the Particle Data Group range of 3.7-7.5 \mu_N and compares well with the experimental result of Bosshard et al. of 4.52 \pm 0.51 \pm 0.45 \mu_N. The interplay between the different pion-loop contributions to the Delta^+ magnetic moment leads to the surprising result that the proton moment may exceed that of the Delta^+, contrary to conventional expectations.Comment: 7 pages, 7 figures, RevTex 4; Updated to include a recent experimental resul

Hadron Masses from the Valence Approximation to Lattice QCD

We evaluate pseudoscalar, vector, spin 1/2 and spin 3/2 baryon masses predicted by lattice QCD with Wilson quarks in the valence (quenched) approximation for a range of different values of lattice spacing, lattice volume and quark mass. Extrapolating these results to physical quark mass, then to zero lattice spacing and infinite volume we obtain values for eight mass ratios. We also determine the zero lattice spacing, infinite volume limit of an alternate set of five quantities found without extrapolation in quark mass. Both sets of predictions differ from the corresponding observed values by amounts consistent with the predicted quantities' statistical uncertainties.Comment: 108 pages of Latex, including 50 PostScript figures, tarred, compressed and uuencoded. IBM-HET-94-3. (The first version of this posting exceeded the size limit. I squeezed the second version in by dropping out the figues. This version gets the figures in but has to be run through Latex and dvips.

Dynamics of Dengue epidemics using optimal control

We present an application of optimal control theory to Dengue epidemics. This epidemiologic disease is an important theme in tropical countries due to the growing number of infected individuals. The dynamic model is described by a set of nonlinear ordinary differential equations, that depend on the dynamic of the Dengue mosquito, the number of infected individuals, and the people's motivation to combat the mosquito. The cost functional depends not only on the costs of medical treatment of the infected people but also on the costs related to educational and sanitary campaigns. Two approaches to solve the problem are considered: one using optimal control theory, another one by discretizing first the problem and then solving it with nonlinear programming. The results obtained with OC-ODE and IPOPT solvers are given and discussed. We observe that with current computational tools it is easy to obtain, in an efficient way, better solutions to Dengue problems, leading to a decrease of infected mosquitoes and individuals in less time and with lower costs.Comment: Submitted to Mathematical and Computer Modelling 25/Oct/2009; accepted for publication, after revision, 22/June/201

The scalar and tensor glueballs in the valence approximation

We evaluate the infinite volume, continuum limit of $0^{++}$ and $2^{++}$ glueball masses in the valence approximation. We find $m_{0^{++}} = 1740 \pm 71$~MeV and $m_{2^{++}} = 2359 \pm 128$~MeV, consistent with the interpretation of $f_0 ( 1710 )$ as the lightest scalar glueball.Comment: (talk presented by A. Vaccarino at Lattice 93) 3 pages of PostScript in uufiles compressed form. IBM-HET-94-

Lattice Gauge Theory -- Present Status

Lattice gauge theory is our primary tool for the study of non-perturbative phenomena in hadronic physics. In addition to giving quantitative information on confinement, the approach is yielding first principles calculations of hadronic spectra and matrix elements. After years of confusion, there has been significant recent progress in understanding issues of chiral symmetry on the lattice. (Talk presented at HADRON 93, Como, Italy, June 1993.)Comment: 11 pages, BNL-4946

Hyperons in Two Flavor Chiral Perturbation Theory

We use two-flavor chiral perturbation theory to describe hyperons. We focus on the strangeness conserving sector, and, as an example, calculate hyperon masses. Convergence of this two-flavor chiral expansion for observables is improved over the three-flavor theory. The cost, however, is a larger number of low-energy constants that must be ultimately determined from lattice QCD data. A formula for the mass of the omega baryon is derived to sixth order in this expansion, and will aid lattice practitioners in scale setting or tuning the strange quark mass.Comment: 14 pages, 3 figs, version published in PL

Interparticle Forces of a Native and Encapsulated Metal-Organic Framework and Their Effects on Colloidal Dispersion

The colloidal properties of suspended metal-organic frameworks (MOFs) are critical for device fabrication and application. Herein, van der Waals attractive, electric double layer repulsive, and steric repulsive forces of a native and encapsulated MOF are quantified for the first time. The van der Waals attractive forces were investigated by conducting environmental ellipsometric porosimetry (EEP) and spectroscopic ellipsometry (SE) on submicron, optical-quality nanoparticle films. The repulsive forces were determined from colloid and material characterization measurements. These data were used to predict suspension properties via extended Derjaguin, Landau, Verwey, and Overbeek theory. The state of dispersion was quantified for comparison with theoretical predictions for nine solvents. The MOF encapsulated with a surface-selective modification showed superior suspension in hydrophobic solvents. These findings should expedite the formulation of MOF colloidal suspensions for future works

CP-PACS results for quenched QCD spectrum with the Wilson action

We present progress report of a CP-PACS calculation of quenched QCD spectrum with the Wilson quark action. Light hadron masses and meson decay constants are obtained at $\beta=$5.9, 6.1, and 6.25 on lattices with a physical extent of 3 fm, and for the range of quark mass corresponding to $m_\pi/m_\rho \approx 0.75$ $-$ 0.4. Nucleon mass at each $\beta$ appears to be a convex function of quark mass, and consequently the value at the physical quark mass is much smaller than previously thought. Hadron masses extrapolated to the continuum limit exhibits a significant deviation from experimental values: with $K$ meson mass to fix strange quark mass, strange meson and baryon masses are systematically lower. Light quark masses determined from the axial Ward identity are shown to agree with those from perturbation theory in the continuum limit. Decay constants of mesons are also discussed.Comment: 12 pages, Latex(espcrc2,epsf), 17 ps figures. Talk presented by T.Yoshi\'e at the International Workshop on ``LATTICE QCD ON PARALLEL COMPUTERS'', 10-15 March 1997, Center for Computational Physics, University of Tsukub