[en] The decay of orthopositronium to three photons can be studied using a method of covariant amplitudes previously used to calculate the Z → 3γ partial decay rate. Three independent amplitudes are needed to describe the decay. The orthopositronium decay amplitudes were calculated analytically to one-loop order using the method of Passarino and Veltman for evaluating one-loop integrals. The amplitudes are given in terms of dilogrithms, logarithms, and other elementary functions. These amplitudes were used to find new, higher precision results for the one-loop decay rate and the contribution to the two-loop decay rate coming from the squares of the one-loop amplitudes

[en] A method for calculating radiative corrections to positronium decay is presented that is direct and allows for calculations to any desired degree of accuracy. An expression for the decay amplitude in terms of the Bethe-Salpeter wave function is employed. The Bethe-Salpeter wave function is evaluated perturbatively in a scheme having a lowest order bound state equation that is exactly soluble. Various gauges are examined to see in which gauge the calculation is most straightforward. Coulomb gauge and Yennie gauge are suggested as preferred gauges. The use of other gauges for virtual photons is permitted with the addition of a correction term, which is obtained. Divergent integrals encountered in this calculation are defined by dimensional regularization. Renormalization in Coulomb gauge is discussed, and a useable form of the Coulomb gauge self-energy function is presented. A physically motivated subtraction scheme is used to define and calculate the renormalization constants Z¹ and A² in Coulomb gauge. One-loop renormalization in Coulomb gauge, as well as in Yennie gauge, presents no difficulties. These two gauges can be renormalized in this scheme without the introduction of unphysical infrared divergences. Using this method the known analytic result for the o(α) correction to the parapositronium decay rate is obtained. The same method is applied to orthopositronium, and the existing theoretical discrepancy in the value of the o(α) correction to the decay rate is resolved. This o(α) correction is obtained with an error which corresponds to an uncertainty in the total rate much smaller than α₂Inα GAMMA/sub LO and α₂ GAMMA_LO (where GAMMA_LO is the lowest order rate)

[en] In this article it is shown that the rho meson can be included in the Skyrme model in a simple, chirally invariant way. Solutions are obtained for the static soliton and time-dependent spinning soliton configurations of the coupled rho and pion fields. Expressions are derived for the vector and axial-vector currents, and predictions are obtained for static properties of the proton and neutron. These predictions are a few percent better than the corresponding predictions of the massive-pion Skyrme model

[en] In this work it is shown how the scattering expansion can be summed to obtain the Schroedinger-Coulomb Green's function in a one-parameter integral representation. The extraction of wave functions from the Green's function is discussed and examples are given

[en] The Skyrme model can be made more realistic by the inclusion of vector mesons along with pions in the effective Lagrangian. Several such models are discussed here. These models are evaluated on the basis of three criteria; meson sector physics, single nucleon properties, and the nucleon-nucleon interaction

[en] Model independent relations for magnetic moments and pseudoscalar meson-nucleon coupling constant ratios are derived for baryons in the chiral soliton approach. Both SU(2) and SU(3) results are obtained. Flavor breaking and 1/N corrections are considered for the SU(3) magnetic moments. Two new sum rules are obtained for the octet moments, and predictions are made for the decuplet moments

[en] The one-loop vertex function in Coulomb-gauge QED has been evaluated. The result is expressed in a parametric integral form. The ultraviolet divergence has been isolated, and the matrix structure of the result has been optimized for applications. Examples of the use of the vertex function are discussed

[en] In this paper the order-α contribution of the inner-vertex graph to the decay rate of orthopositronium is obtained in analytic form

[en] The Fried-Yennie gauge in QED is a covariant gauge with agreeable infrared properties. That is, the mass-shell renormalization scheme can be implemented without introducing artificial infrared divergences, and terms having spuriously low orders in α disappear in certain bound-state calculations. The photon propagator in the Fried-Yennie gauge has the form D_β^μν(k)=(-1/k²)[g^μν+βk^μkν/k²], where β is the gauge parameter. In this work, I show that the Fried-Yennie gauge parameter is β=2/(1-2ε) when dimensional regularization (with n=4-2ε dimensions of spacetime) is used to regulate the theory

[en] In this report the order-α correction to the lowest-order orthopositronium decay rate due to the two outer-vertex graphs is obtained in analytic form