Pole Exchange Research Articles

Regge pole exchange analysis of [formula omitted] at 7.3 GeV/ c

A Regge pole exchange model is applied to the reaction K + p → K ∗ O (890)π + p at 7.3 GeV/c . The reaction is well described by exchanges of pion and Pomeranchuk trajectories with the Pomeranchuk exchange approximated by either a diffraction mechanism or on-mass shell π +p scattering. The model fits the production of the Q enhancement and also gives an adequate description of the virtual π +p scattering.

Double Regge pole exchange and K −p backward scattering

An estimate of the double Regge exchange contribution to d σ/d u (K −p) at u=0 suggests that a break in the energy dependence from the presently observed s −10 to an s −3 behavior should occur at about 5 GeV/ c. Further tests of the model are discussed.

A double Regge model of production processes

Abstract The Feynman diagram method is used to calculate the amplitude for a bi-Regge pole exchange for multiparticle production processes at very high energies. The two cases of normal and abnormal coupling at the Reggeon-Reggeon-particle vertex are considered. Certain differential cross sections are evaluated and compared to previous results.

A Regge-pole model of π− + p → η + n polarization

Predictions of the polarization in the reaction π− + p → η + n are made using a simple Regge pole model. The polarization arises from the interference of an A2 Regge pole exchange in the crossed channel with direct channel resonances represented by Breit-Wigner formulae. A fit to the differential cross-section in the energy range 3 to 18 GeV using constant residues is also obtained.

Exchange current and deuteron photodisintegration at threshold

The contribution from the meson exchange current to the deuteron photodisintegration amplitude at threshold is calculated by taking into account the next nearby singularities beyond the nucleon exchange poles in the crossed channels. The procedure is based on potential theory. Starting with the corresponding fourth order Feynman amplitude with the deuteron-nucleon vertex on the mass shell a local “exchange potential” is derived. Its contribution to the amplitude is calculated by using the Hulthén function for the initial deuteron state (thus including the off-mass shell properties of the deuteron-nucleon vertex) and the effective range approximation for the final scattering state. The result is combined with the direct γ-nucleon contribution calculated by Austern and Rost 1) and agrees with experiment within the limits of error.

Impact-ParameterK-Matrix Approach to High-Energy Peripheral Interactions

An approximate dispersion-theoretic treatment of peripheral inelastic processes is introduced with the aid of a $K$-matrix formalism based on the impact-parameter representation of Blankenbecler and Goldberger. The method allows the use of one-meson exchange poles as a framework for constructing a multichannel scattering amplitude which satisfies unitarity in the high-energy region, allowing for an indefinitely large number of open channels. The reaction matrix is time-reversal symmetric and exhibits any other symmetries of the pole terms. Applications are numerically worked out for models of high-energy $\overline{K}p$ and $\mathrm{np}$ charge exchange, and in the former case satisfactory agreement with experiments is achieved. A qualitative discussion is given of peripheral isobar production models. The high-energy $\overline{p}p$ and $\overline{K}p$ diffraction scattering is examined, as well as the agreement of the small-momentum-transfer behavior with a simple model not involving Regge poles. The method sheds no light on the difference between $\overline{p}p$ and $\mathrm{pp}$ scattering at high energies.

K+ΛPhotoproduction from Hydrogen at 1200 MeV

Measurements of the angular distribution of the cross section for the photoproduction of the ${K}^{+}\ensuremath{\Lambda}$ system from hydrogen have been made in the c.m. angular interval from 15\ifmmode^\circ\else\textdegree\fi{} to 85\ifmmode^\circ\else\textdegree\fi{} at a photon energy of 1200 MeV. The reaction was identified by detecting the ${K}^{+}$ mesons with a magnet spectrometer and a velocity selection system consisting of two \ifmmode \check{C}\else \v{C}\fi{}erenkov counters. The angular distribution at this energy is very similar to that at lower energies in that it is peaked forward and is easily fit with a quadratic in ${cos\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}$. Special emphasis was placed on the forward direction in an attempt to find evidence for the one-$K$-exchange pole. A Taylor-Moravcsik analysis of the data is presented, but the results are inconclusive.

A determination of the pion-nucleon coupling constant from n-p scattering at 350 MeV

The n-p angular distribution near the backward direction was measured by counting recoil protons from a liquid hydrogen target. Data were obtained at thirteen angles between 114° and 174° centre of mass, with an error ≈1.4%. The angular distribution was fitted by using backward and forward single pion exchange poles plus a polynomial. Previously published data were used to establish the absolute scale of the differential cross sections with an error appreciably smaller than the fitting error. The effects on the analysis were investigated of excluding certain points, varying the meson mass, using an alternative analytical form and including possible two-pion poles. It was concluded that the contribution from the single pion exchange pole had been definitely established, with a reasonable value of g 2 .