Double giant dipole resonance in the ( pi -, pi +) reaction.

title: Solution of the equations for the green’s functions of a two dimensional relativistic field theory
abstract: SummaryThe explicit solution of the coupled set of equations for the Green’s functions for the self-coupled field theory model of Thirring is given. It is found that the infra-red problem causes no special difficulty. The question of how to define products of singular field operators at coincident space-time points arises and it is shown that the commutation relations for such products are not consistently given by making use of the formal expressions and the canonical commutation relations. The problem of gauge invariance in an external field is studied and it is shown that:a) the current and charge density do not commute at equal times, andb) this is necessary for and consistent with the gauge invariance of the field equations.RiassuntoSi dà la soluzione esplicita del gruppo accoppiato di equazioni per le funzioni di Green per il modello auto-accoppiato della teoria del campo di Thirring. Si trova che il problema infrarosso non genera particolare difficoltà. Sorge la questione sul modo di definire i prodotti degli operatori di campo singolari in punti coincidenti dello spaziotempo e si mostra che le relazioni di commutazione per questi prodotti non vengono espresse coerentemente facendo uso delle espressioni formali e delle relazioni di commutazione canonica. Si studia il problema della invarianza di gauge in un campo esterno e si mostraa) che la corrente e la densità di carica non commutano in tempi uguali, eb) che questo è necessario per l’invarianza di gauge delle equazioni del campo, e coerente con essa.

title: The Quark Model Pion and the PCAC Pion
abstract: An important problem in the theory of strong interactions is furnished by the least massive hadrons, the pseudoscalar meson octet. The difficulty is that there are two such octets.

title: Simple semiclassical model for the rotational states of mesons containing massive quarks
abstract: We present a semiclassical relativistic model for the orbital spectra of mesons, based on the assumption of a universal, flavor-independent linear confining interaction. Flavor dependence of the spectra arises from the quark masses.

title: Vacuum polarization in quantum electrodynamics

title: THE M.I.T. BAG, 1976 EDITION
abstract: We assume (1,2) that hadrons consist of colored quarks and gluons, and that the dynamics is described by the standard non-Abelian gauge field theory. However, we also assume that space exists in two phases. In the first phase, I, ordinary space, colored fields are not carried on the spatial points. In the second phase, II, which is the kind of space inside hadrons, the spatial points carry colored field variables; Further, we assume that the second kind of space carries an energy per unit volume, BGT0, greater than the first kind and that the second kind of space can exist as bubbles in the first kind. This is done in a relativistically covariant way, by associating with the second kind of space a local stress-energy of the form, -gμν B. The phase II space is called a bag.

title: Low-energy technicolor Lagrangian with vector mesons.
abstract: We apply techniques used in QCD and the implied chiral symmetry to motivate a low-energy Lagrangian for technicolor theories. This allows one to cleanly introduce the gluon and the weak gauge bosons at the technifermion level. The Higgs mechanism and techni-vector-meson dominance are displayed. The effect of vector dominance on the {ital W} and {ital Z} masses, the techni-{omega} and techni-{rho} couplings, and the sizable enhancement by the latter on {ital W} and {ital Z} production are demonstrated. Differences between our results and some published results are discussed. The incorporation of extended technicolor interactions is also presented.

title: Experimental investigation of nonlinear dynamics in the Fermilab Tevatron.
abstract: The nonlinear dynamics of transverse particle oscillations in the Tevatron is studied experimentally and compared with prediction. Accurate measurements of various phase-space features are obtained. A theoretically expected metastable state of the accelerator, with particles captured on nonlinear resonance islands, is demonstrated experimentally, and stability of the state is investigated.

title: Realistic pseudoscalar-vector chiral Lagrangian and its soliton excitations.
abstract: A reasonable low-energy chiral Lagrangian of vectors and pseudoscalars involves three a priori unknown coefficients for terms proportional to the Levi-Civita symbol epsilon/sub ..mu..//sub ..nu..//sub ..cap alpha..//sub ..beta../. We argue that these cannot, from a theoretical standpoint, be reliably determined by consideration of electromagnetic processes. Hence we use purely strong-interaction processes which enable us to determine two out of three of these. We examine the nucleon as a soliton excitation in the model and find that adjustment of the third parameter does not greatly change the, in most respects accurate, description of the nucleon obtained in a previous treatment by Meissner, Kaiser, and Weise. The paper includes a new and careful formulation of the addition of electromagnetism to the full Lagrangian.

title: Driven response of a trapped particle beam.
abstract: The dynamics of a metastable beam of particles injected'' into artificially excited resonance islands in the Fermilab Tevatron is studied. Evolution of the captured beam distribution is measured by an externally detectable coherent signal. Dynamical partitions observed in the control space of amplitude and tune of a focusing modulation are consistent with an equivalent mode of an ensemble of driven gravity pendula. The model's single parameter, the island tune {ital Q}{sub {ital I}} of small oscillations, is inferred as the central frequency of resonant detrapping under this weak drive.

title: Measurements of a Hamiltonian system and their description by a diffusive model.
abstract: The dynamics of transverse particle oscillations in the Fermilab Tevatron, artificially made nonlinear, is studied by observing beam profiles over periods up to an hour. A ``diffusive'' model with amplitude-dependent diffusion coefficient gives a quantitatively accurate description of beam evolution. The evolution is influenced strongly by nonlinear resonance.