Showing papers on "Elementary particle published in 1968"

Extension of the Low Soft-Photon Theorem

Abstract: The Low theorem is applied to the radiative cross section for unpolarized particles. It is shown that the first two terms of an expansion in the photon energy depend on the unpolarized, nonradiative cross section only.

Possibility of baryon--antibaryon enhancements with unusual quantum numbers.

Abstract: Arguments are presented in favor of $B=0$ enhancements in the 10, 10*, and 27 representations of SU (3) which decay mainly into a baryon and an antibaryon.

Sources and Magnetic Charge

Abstract: A beginning is made on a phenomenological reconstruction of the theory of magnetic charge. The concept is introduced by reference to a new kind of photon source. It is shown that photon exchange between different source types is relativistically invariant. The space-time generalization of this coupling involves an arbitrary vector. The only way to remove a corresponding arbitrariness of physical predictions is to recognize the localization of charge and impose a charge quantization condition. The consideration of particles that carry both kinds of charge loosens the charge restrictions. The great strength of magnetic attraction indicated by $\frac{{g}^{2}}{4\ensuremath{\pi}}=4(137)$ suggests that ordinary matter is a magnetically neutral composite of magnetically charged particles that carry fractional electric charge. There is a brief discussion of such a magnetic model of strongly interacting particles, which makes contact with empirical classification schemes. Additional remarks on notation, and on the general nature of the source description, are appended.

Strong-interaction sum rules for pion--hadron scattering.

Abstract: Using Regge high energy behavior, the chiral algebra of charges, and pion pole dominance of the divergence of the axial-vector current, all the strong interaction sum rules which hold for elastic pion-hadron scattering amplitudes at t=O are derived. These include charge algebra sum rules as well as superconvergence relations. We distinguish between \"pure\" t==O sum rules (Class I) and \"extrapolated\" sum rules (Class 11) and relate them to the evenness or oddness of the helicity flip in the t-channel. Using the explicit crossing relations for the relevant helicity amplitudes, the connection of Class I superconvergence relations to the charge algebra sum rules is established, and the algebraic structure of Class I sum rules is then discussed in terms of representations of the SU(2) X SU(2) chiral algebra of charges, for particle states moving with infinite momentum. The properties of the mass operator in SU(2) X SU(2) are analyzed and it is shown that even in the presence of SU(2) X SU(2) symmetry breaking the (mass)' values of all the (mixed) eigenstates of an irreducible representation of the algebra are predicted to be equal, Since these eigenstates can be determined from the matrix elements of the vector and axial-vector charges, a large number of non-trivial mass relations are obtained. Class II superconvergence relations, sum rules for t#O, and sum rules for the derivative with respect to t of the scattering amplitude at t--O are briefly discussed. Many applications of the strong interaction sum rules are presented including a model consisting of I=0 and I=1 scalar, pseudoscalar, vector, and axial-vector mesons. The predictions of the model as well as those of the other sum rules are derived and found to be in satisfactory agreement with experiment.

Particles and sources.

Abstract: It is proposed that the phenomenological theory of particles be based on the source concept, which is abstracted from the physical possibility of creating or annihilating any particle in a suitable collision. The source representation displays both the momentum and the space-time characteristics of particle behavior. Topics discussed include: spin and statistics, charge and the Euclidean postulate, massless particles, and $S{U}_{3}$ and spin. It is emphasized that the source description is logically independent of hypotheses concerning the fundamental nature of particles.

Glauber Corrections and the Interaction between High-energy Hadrons and Nuclei

Abstract: Charge screening and confinement of zero-mass fermions (quarks) in two-dimensional electrodynamics (QED/sub 2/) are due to the transition of the local charges into the vacuum of the system under the action of a field that changes the topological number. An exact solution of the quark structure of vacuum for two QED/sub 2/ variants shows that this problem is consistent with this phenomenon. The structure of the vacuum is therefore directly related to the Adler anomaly and to the character of the change of the topological numbers of the fields in dynamic processes. The obtained solutions make it possible to investigate in explicit form the properties of the chiral condensate whose existence is also a direct consequence of the Adler anomaly.

Nuclear and Particle Physics

Abstract: Part 1: Nuclear Physics 1. The atomic nucleus. 2. Experimental techniques. 3. General properties of nuclei. 4. Nuclear models. 5. Decay of unstable nuclei. 6. Nuclear reactions. Part 2: Particle Physics 7. Sub-nuclear physics - an overview. 8. Symmetry transformations and conservation laws. 9. Hadron spectroscopy. 10. The quark model. 11. Weak interactions. 12. Hadron structures and the parton model. 13. The standard model. 14. Experimental test of the standard model. 15. Beyond the standard model: a brief survey.

Quark-Diquark Model of Baryons and SU (6)

Abstract: A model in which a baryon can be regarded as a bound state of two particles has been generalized to be approximately invariant under $\mathrm{SU}(6)$. In the model, one of the constituent particles of a baryon can be regarded as a quark and the other particle can be considered as a tightly bound state of two quarks, or diquark. The quark is taken to belong to a six-dimensional representation of $\mathrm{SU}(6)$, while the diquark is taken to belong to a twenty-one-dimensional representation. With this model, which can be considered as a specific dynamical approximation to the three-quark model, the baryon medium-strong mass splittings are calculated beyond lowest-order perturbation theory. The model provides a mechanism for breaking the Gell-Mann\char22{}Okubo baryon-octet mass formula while breaking the baryon-decuplet equal-spacing rule by a smaller amount.

Group Dynamics of Elementary Particles

Abstract: It is proposed that particle interactions can be described by means of simple group operations in non-compact Lie groups. Prescriptions for the structure of these group operations are formulated which are motivated by the study of simple models, in particular of the dynamics of the hydrogen atom. If they are fulfilled we call the structure “group dynamics”. Neglecting at first internal symmetries, a few simple models are investigated in which group dynamics is possible. The group O(3,1) turns out to describe the coupling of pseudoscalar mesons, O(4,2) that of photons to baryons quite well: The pionic decay rates of baryon resonances up to spin 19/2 and the electromagnetic form factors of the nucleons are predicted in good agreement with experiment. The internal symmetry SU(3) is included in the O(3.1) model of the pionic coupling in the simplest way, by assuming O(3,1) × SU(3) to be the dynamical group. This gives rise to a minimal symmetry breaking of the amplitudes and relates it to the mass differences in SU(3) multiplets: The amplitude consists of a product of a SU(3) Clebsch Gordan coefficient and a universal function of the velocity of the final baryon. The way the particle masses enter the decay rates is uniquely prescribed in this approach. The agreement with experiment is excellent. Finally, the connection of this purely algebraic approach with related ideas, like the use of infinite component wave equations, is discussed.

Ultraviolet divergences in radiative corrections to weak decays

Abstract: The problem of second-order radiative corrections to general semileptonic weak decays is considered. Previous results on ultraviolet divergences in the calculations for zero-momentum-transfer $\ensuremath{\beta}$ decays can be proven for the general process, provided that the models of the strong interactions are restricted to renormalizable theories of elementary fermion fields coupled to neutral massive vector bosons through a conserved vector current. A possible method for calculating finite radiative corrections to actual processes is also discussed.

Elastic scattering from deuterium.

Abstract: Scattering of elementary particles from deuterons at BeV energies is considered. Corrections to the Glauber theory, resulting from violations of its high-energy and small-momentum-transfer assumptions, are found significant for experiments already performed. The most important correction results from including the principal-value part of the propagator in double scattering. Triple and higher-order multiple scattering are calculated in a model and are predicted to be important at momentum transfers of $\ensuremath{-}tg4$ Be${\mathrm{V}}^{2}$. Available data on the energy dependence of the "screening correction" to deuteron total cross sections are shown to disagree with the Glauber theory, and a possible phenomenological treatment of that disagreement is discussed.