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F. T. Hawes

Publications and source records attributed to F. T. Hawes.

3 recordsLinked to original sources

Electromagnetic form factors of light vector mesons

The electromagnetic form factors G_E(q^2), G_M(q^2), and G_Q(q^2), charge radii, magnetic and quadrupole moments, and decay widths of the light vector mesons rho^+, K^{*+} and K^{*0} are calculated in a Lorentz-covariant, Dyson-Schwinger equation based model using algebraic quark propagators that incorporate confinement, asymptotic freedom, and dynamical chiral symmetry breaking, and vector meson Bethe-Salpeter amplitudes closely related to the pseudoscalar amplitudes obtained from phenomenological studies of pi and K mesons. Calculated static properties of vector mesons include the charge radii and magnetic moments: r_{rho+} = 0.61 fm, r_{K*+} = 0.54 fm, and r^2_{K*0} = -0.048 fm^2; mu_{rho+} = 2.69, mu_{K*+} = 2.37, and mu_{K*0} = -0.40. The calculated static limits of the rho-meson form factors are similar to those obtained from light-front quantum mechanical calculations, but begin to differ above q^2 = 1 GeV^2 due to the dynamical evolution of the quark propagators in our approach.

nucl-th

Chiral Symmetry Breaking in Strongly Coupled Quenched QED$_4$ Using the Dyson-Schwinger Equation Formalism

We study chiral symmetry breaking in quenched strong-coupling QED$_4$ in arbitrary covariant gauge within the Dyson-Schwinger equation formalism. A recently developed numerical renormalization program is fully implemented. Results are compared for three different fermion-photon proper vertex {\it Ansätze\/}: bare $γ^μ$, minimal Ball-Chiu, and Curtis-Pennington. The procedure is straightforward to implement and numerically stable. We discuss the chiral limit and observe that in this limit the renormalized axial current is conserved. A detailed study of residual gauge dependence due to the vertex choice is in progress. The relevance for lattice studies is discussed.

hep-lat

Dyson-Schwinger equations and their application to nonperturbative field theory

Two examples of recent progress in applications of the Dyson-Schwinger equation (DSE) formalism are presented: (1) Strong coupling quantum electrodynamics in 4 dimensions (QED$_4$) is an often studied model, which is of interest both in its own right and as an abelian model of quantum chromodynamics (QCD). We present results from a study of subtractive renormalization of the fermion propagator Dyson-Schwinger equation (DSE) in massive strong-coupling quenched QED$_4$. The procedure is straightforward to implement and numerically stable. (2) The Bethe-Salpeter equation (BSE) with a class of non-ladder scattering kernels is solved in {\it Minkowski space} in terms of the perturbation theory integral representation (PTIR). We consider a bound state of two spinless particles with the formal expression of the full scattering kernel in a $ϕ^2σ$ scalar model. We derive an integral equation for the weight function with a real kernel. We recover as a check results for the massive scalar ladder approximation.

hep-ph