Analysis of full-QCD and quenched-QCD lattice propagators

Recent lattice-QCD results for the dressed-gluon propagator are used within the quark Dyson-Schwinger equation to determine the gluon-quark vertex dressing necessary to reproduce the lattice-QCD results for the dressed-quark propagator. Both quenched and full QCD lattice simulations, for a range of low quark current masses, are analyzed. The chiral extrapolation is made through this continuum DSE form. Resulting chiral and physical pion observables are investigated.Comment: Talk given at PANIC 2005 Conference, Santa Fe, October 2005. To be published in the Proceeding

Vector meson form factors and their quark-mass dependence

The electromagnetic form factors of vector mesons are calculated in an explicitly Poincar\'e covariant formulation, based on the Dyson--Schwinger equations of QCD, that respects electromagnetic current conservation, and unambiguously incorporates effects from vector meson poles in the quark-photon vertex. This method incorporates a 2-parameter effective interaction, where the parameters are constrained by the experimental values of chiral condensate and $f_{\pi}$. This approach has successfully described a large amount of light-quark meson experimental data, e.g. ground state pseudoscalar masses and their electromagnetic form factors; ground state vector meson masses and strong and electroweak decays. Here we apply it to predict the electromagnetic properties of vector mesons. The results for the static properties of the $\rho$-meson are: charge radius $= 0.54 {\rm fm}^2$, magnetic moment $\mu = 2.01$, and quadrupole moment ${\cal Q} = -0.41$. We investigate the quark mass dependence of these static properties and find that our results at the charm quark mass are in agreement with recent lattice simulations. The charge radius decreases with increasing quark mass, but the magnetic moment is almost independent of the quark mass.Comment: 13 pages, 7 figure

Covariance, Dynamics and Symmetries, and Hadron Form Factors

We summarise applications of Dyson-Schwinger equations to the theory and phenomenology of hadrons. Some exact results for pseudoscalar mesons are highlighted with details relating to the U_A(1) problem. We describe inferences from the gap equation relating to the radius of convergence for expansions of observables in the current-quark mass. We recapitulate upon studies of nucleon electromagnetic form factors, providing a comparison of the ln-weighted ratios of Pauli and Dirac form factors for the neutron and proton.Comment: 9 pages, 2 figures. Contribution to proceedings of Workshop on Exclusive Reactions at High Momentum Transfer, May 21-24, 2007, Jefferson Lab, Newport News, V

The role of markets in food availability and market integration among smallholder farmers: the case of Western Kenya [Poster]

Poster presented at Tropentag 2013. International Research on Food Security, Natural Resource Management and Rural Development. "Agricultural development within the rural-urban continuum". Stuttgart-Hohenheim (Germany), Sep 17-19 2013

Crop species diversity in smallholder farms in Western Kenya and their contribution to food security

Poster presented at First International Conference on Global Food Security. Noordwijkerhout (The Netherlands), 29 Sep - 02 Oct 2013

Quark-gluon vertex model and lattice-QCD data

A model for the dressed quark-gluon vertex, at zero gluon momentum, is formed from a nonperturbative extension of the two Feynman diagrams that contribute at 1-loop in perturbation theory. The required input is an existing ladder-rainbow model Bethe-Salpeter kernel from an approach based on the Dyson-Schwinger equations; no new parameters are introduced. The model includes an Ansatz for the triple-gluon vertex. Two of the three vertex amplitudes from the model provide a point-wise description of the recent quenched lattice-QCD data. An estimate of the effects of quenching is made.Comment: 4 pages, 3 figure

Going beyond hunger: Linking food supplies to global malnutrition

International food security and nutrition studies focus mainly on hunger rather than dietary diversity and the nutritional requirements essential for a productive life. The authors present a method that processes Food and Agriculture Organization food supply data into World Health Organization food groups to determine whether national food supply satisfies nutritional requirements for medium energy intake (i.e. c.2200 calories per day) rather than minimum energy intake. They employ a modified version of the International Food Policy Research Institute’s 2013 Global Hunger Index to group nations for comparison. The results show that most nations have a deficit in at least one of four required food groups. However, many developed Mediterranean nations with low levels of hunger display an adequate supply of all food groups. The positioning represents a successful model for managing the nutrition transition from plant-based diets to the consumption of animal protein, oils, fats, and sugars and other carbohydrates. Additionally, the results suggest that health risks associated with overweight and obesity may increase with societal development. Accordingly, the authors conclude that information on medium energy requirements should be combined with complementary socio-economic analysis to inform food and nutrition research and policy

On Nucleon Electromagnetic Form Factors: A Pre'cis

Electron scattering at large Q^2 probes a nucleon's quark core. This core's contribution to electromagnetic form factors may be calculated using Poincare' covariant Faddeev amplitudes combined with a nucleon-photon vertex that automatically fulfills a Ward-Takahashi identity for on-shell nucleons. The calculated behaviour of G_E^p(Q^2)/G_M^p(Q^2) on 2<Q^2(GeV^2)<6 agrees with that inferred from polarisation transfer data, and exhibits a zero at Q^2\approx 6.5 GeV^2. There is some evidence that F_2(Q^2)/F_1(Q^2) \propto [\ln(Q^2/\Lambda^2)]^2/Q^2 for Q^2>6 GeV^2.Comment: Contribution to the proceedings of "Baryons 04," the 10th International Conference on the Structure of Baryons, 25-29/Oct./04, Ecole Polytechnique, Palaiseau; 5 pages, 3 figure

Availability of Pulses in Rural Karnataka: Need to Use District-level Data

In a response to "Making Pulses Affordable Again"(EPW, 7 January 2017) by P K Joshi, Avinash Kishore and Devesh Roy this article aims to bring to the fore the importance of using district-level data on nutritional levels and pulse production, that can better inform public policy and help improve human development indicators