A relation is established between the reaction due to the radiation of a multiple particle and the reaction arising from the minus field, i.e., half the difference of the retarded and advanced self-fields. This leads to a new representation of the reaction terms.

A generating functional to be used for calculating gauge-invariant Green's functions of a non-Abelian gauge theory is constructed in terms of an unconstrained external current. This functional is a singular distribution and so must be treated as the limit of a well-defined functional, one...

The stationary temperature distributions along a conducting wire, surrounded by a gas, through which a constant electric current is passed, is analysed within the framework of a Hamiltonian formalism. The nature of the inhomogeneous solutions, which occur when the homogeneous solutions become...

The Boltzmann equations for a formal bimolecular chemical reaction in homogeneous gas phase are transformed into an infinite system of quadratic differential equations, by expanding the distribution functions of the molecules into the Grad polynomials. The properties of these expanded Boltzmann...

The existence is shown of bound complexes of three magnons in a two-dimensional simple cubic Heisenberg ferromagnet. The Heisenberg spin hamiltonian is replaced by Dyson's boson hamiltonian. The spurious features of this hamiltonian are treated explicitly. Using Faddeev's formalism, detailed...

Thermodynamic functions are needed for the discussion of phase transitions in gaseous and solid state plasmas. In this paper detailed numerical data for the Hartree-Fock and the Montroll-Ward (ring sum) contributions to the pressure for symmetrical multicomponent plasmas are given at any degree...

The treatment of a previous paper on systems with many-particle interactions is generalized to hamiltonians containing an analytic function of a number of short-range interaction operators V, which are normalized. An exact expression for the free energy per particle in the thermodynamic limit...

In this paper a low-energy-electron diffraction theory for molecular crystals is presented. The influence of the bulk Frenkel excitons on the intensity of the specular beam is studied.

The expansion theorem of quantum field theoy relating Heisenberg operators to asymptotic free-field operators is rewritten by means of the time-path technique, originally due to Schwinger, which to date has only found application in statistical mechanics. The theorem is combined with...

New lower bounds for the susceptibility in terms of the first and second moments are derived. These lower bounds are applied in the problem of the electric susceptibility.