Showing papers on "Pseudoscalar published in 1970"

General analysis of the vector-meson dominance model predictions for meson decays.

Abstract: Using the vector-meson dominance model,SU3 symmetry and the ω-ϕ and η-X0 mixing hypotheses (recent results seem to contradict the possibility of a mixing between the η and the E (1420)-meson) the decays of the pseudoscalar and the vector mesons are systematically investigated. The explicit expressions for phase-space evaluations are listed. The predictions of the model concerning the branching ratios and decay rates are discussed in detail, classifying those which are independent of some coupling constants, mixing angles and (or) experimental inputs. A consistent picture is obtained for the π0→γγ and the ω→π0γ decay modes and the ω and ϕ branching ratios and a resonable agreement is generally found with the experimental situation, which is sometimes rather unclear. Our results seem to disagree with a recent determination of the branching ratios of the ω→хγ and ω→π0π0γ decay modes.

Generating functionals, ward identities, and scalar mesons.

Abstract: We shall present a general and concise treatment of Ward identities in current algebra with broken symmetry. An application is also presented to the mass spectrum and leptonic decay constants of the scalar and pseudoscalar mesons.

Coupling parameters of pseudoscalar meson photoproduction on nucleons

Abstract: We have given a general view of the coupling parameters of the photoproduction of pseudoscalar mesons on nucleons. We have shown that the magnetic transition moment for the Δ(1230) resonance is quite well established; the electric quadrupole transition is very small and different calculations yield values between 0 to –6% of the magnetic transition. Moreover, the decay widths of the transitions of the excited nucleon states D13(1530), F15(1690) and to a smaller reliability also of F37(1950) and S11(1560) can be determined from the presently available data of pion photoproduction.

The Fundamental Nuclear Interaction

Abstract: GOPEB based upon known mesons have been found which realistically describe a massive accumulation of the experimental nuclear data up to 400 Mev. The N-N potential according to these models consists primarily of weak residual central terms surviving the cancellation of large repulsive and attractive vector and scalar static components; relativistic interactions arising from the exchange of pseudoscalar, vector, and scalar mesons and dipole type terms arising from the ρ meson. The major dynamic terms are direct analogs of magnetic interactions illustrated in Fig. 1. Allowance must be made for the effective dependence of the coupling constants upon spin and isospin states. The nucleons are distributed sources which give rise to nonsingular generalized Yukawa functions in N-N potentials.

Nuclear Coulomb Effects on the Induced Pseudoscalar Interaction in the Theory of Muon Capture by Nuclei

Abstract: Variations of the strength of the induced pseudoscalar coupling Cp in muon capture by nuclei due to nuclear Coulomb effects on both pion propagator and muon wave function are calculated by assuming point nuclei with the effective charge Zerre. Those Coulomb effects depend not only on Zcrr but also on the energy of the neutrino emitted in the process in consideration. In the low-energy region of the neutrino the Coulomb effects on both quan­ tities are nearly cancelled out by each other, while in the high-energy region (corresponding to the case of normal muon capture) a considerable net effect remains and Cp is reduced by several percent (5---....9% for Zeff=7.47"-'l6.17, i. e. for Z=S"-'20) compared with its magnitude when no Coulomb effects are taken into account.

On the Chiral Transformation Properties of the Pseudoscalar-Vector-Vector Interaction.

Abstract: I t has already been observed by many authors (1.3) that the partially conserved axial-current hypothesis (a), PCAC, and the current-field proportionality (a) lead to a vanishing ¢~p~ coupling in the effective-Lagrangian formalism (e). In order to eliminate this difficulty one has to introduce directly an (opT: coupling that violates PCAC. It is the scope of this work to discuss, in the framework of effective Lagrangiaus and the field-current proportionality (~), the transformation properties of this pseudoscalarvector-vector interaction under the chiral SU3Q SUn group. We consider the nonet of pseudosealar fields P and the nonet of dependent or independent scalar fields S to transform like the representations (3, g) and (3, 3) of SUaQ SUs. That is, the 3 × 3 matrix B = S + iP transforms like (3, $) and B + ~ S i P like (g, 3). The 8 vector mesons V# and their 8 ehiral partners At, transform like the representations (8, 1) and (1, 8) of SU3Q SUs. That is, the 3 × 3 traceless matrices /~+) = V#÷~¢# transform like (8, 1) and 2~ ' = V~--g~/# like (1, 8). The SUn scalar 1 transforms like the representation (1, 1) of SUaQ SUa. vector meson ¢% It is then at once evident that one cannot construct an SUsQSUsinvar ian t VVP or ~IVP coupling. Let us furthermore demonstrate that it is not possible to have an SUaQ SUsinvariant interaction of two vector, one pseudoscalar and one scalar meson when the vector mesons couple through their covariant curls in order to maintain the currentfield proportionality. That is, one cannot generate a vector-vector-pseudoscalar meson interaction through that four-meson interaction when the nonvanishing vacuum expectat ion value of the T = 0 scalar fields is considered.

Diffraction Scattering for Inelastic Processes

Abstract: Previous treatments on high-energy scattering in quantum electrodynamics are extended to diffractive inelastic processes. We explore the model in which the diffractive excitation proceeds through the exchange of vector mesons. Six inelastic impact factors are explicitly calculated in the lowest order: (1) scalar to scalar, (2) pseudoscalar to pseudoscalar, (3) vector to vector, (4) axial vector to axial vector, (5) scalar to axial vector, and (6) pseudoscalar to axial vector. For all six of these impact factors, the masses of the incoming and outgoing particles may be different; and for the last two impact factors, the spins and the parities of the incoming and outgoing particles may be different. The nonvanishing of the impact factors demonstrates that mass, spin, and parity can change during a diffractive process. We also conclude that $C$ (charge conjugation quantum number), $S$ (strangeness), $I$ (isotopic spin), $B$ (baryon number), and $G$ parity, etc., must remain the same during a diffractive process. Some general properties of the impact factor are also discussed.

Two-photon decays of mesons

Abstract: An attempt is made to describe the radiative decays of pseudoscalar mesons in the framework of the nonlinear spinor theory. In a first approximation reasonable decay widths can be calculated for the neutral pion and the ν-meson.

Estimate of the Mass of the Ninth Pseudoscalar Meson

Abstract: Using Gell-Mann's ansatz for the $\mathrm{SU}(3)\ifmmode\times\else\texttimes\fi{}\mathrm{SU}(3)$ symmetry-breaking part in the strong Hamiltonian density, a sum rule for the spin-zero spectral functions of the pseudoscalar axial-vector current octet is derived. Saturating the sum rule with the lowest-lying states, the mass of the ninth pseudoscalar meson can be estimated as $m\ensuremath{\approx}1$ GeV.

Capture rate for the reaction3He+μ-→3H+ν

Abstract: The capture rate for the process3He+μ-→3H+ν is calcultated following the usual approach involving an effective Hamiltonian. The trinucleon wave function that we have used is a solution to the three-body wave equation with separable two-body potentials including the tensor forces. It is a linear combination of the2S symmetric states, the mixed-symmetry2S state and the three mixed-symmetry4D states. The calculated capture rate agrees in general with existing work. The ratio of the induced pseudoscalar and axial vector coupling constants, mμFp/FA, that is deduced from this calculation is somewhat smaller than that predicted by the Goldberger-Treiman relation. It is pointed out that since the contribution of theD-state apparently decreases the capture rate and consequently the pseudoscalar coupling constant, it is reasonable to expect that a wave function with a smallerD-state admixture will yield results consistent with both the radiative-muon-capture results and the Goldberger-Treiman prediction. A preliminary calculation and brief discussion of this possibility is also given.

Mass Operator in the SU(3)-Symmetric Strong Coupling Theory With Pseudoscalar Mesons

Abstract: The strong coupling approximation scheme has been used in the quantum field theory almost only for the meson field interacting with a static fermion source. The first works in this direction considered the ΠN system [1]. At the end of the 4O’s the interest decreased, but later the excited isobaric states of the nucleon predicted by the strong coupling theory were found experimentally as nuc- leon resonances. New interest arose after the discovery of the SU(3) symmetry of strongly interacting particles [2] with the aim to connect the properties of different SU(3)-multiplejbs by a dynamical theory.

Mass operator in the su(3)-symmetric strong coupling theory with pseudoscalar mesons.

Abstract: In this paper theSU(3)-symmetric model of a static baryon octet source interacting with pseudoscalar meson octet fields by the coupling of Yukawa type is considered in the strong coupling limit. Using the result derived earlier that the isobaric states form the basis of the unitary irreducible representation of the dynamical group G=T 24⊗ [SU(3) ⊗SU(2)], the mass operator is specified by the kinetic part of the Hamiltonian as a particular element of the universal enveloping algebra of the symmetry groupSU(3) ⊗SU(2) acting in the space of isobaric states.