arXiv subjects

A. Funk

Publications and source records attributed to A. Funk.

4 recordsLinked to original sources

arXiv2001

Nucleon-Nucleon and Nucleon-Nucleus Optical Models for Energies to 3 GeV and the Question of NN Hadronization

Within the key issues of hadronic physics one of the interesting issues in nuclear physics is whether there is a transition region between meson-nucleon and quark-gluon degrees of freedom in the NN interaction. This question is relevant for pairs of free nucleons as well as for nucleon pairs immersed in nuclear matter. From NN phase shifts we deduce a dibaryonic scale of 1 GeV for the soft core NN potential strengths at nucleon separation r equal 0.25 to 0.5 fm. A short range intermediate transition, with fusion and fission of the two scattered nucleons into a dibaryon with prevailing quark-gluon dynamics, is conjectured from NN optical models for T-lab greater 1.5 GeV. From efforts and progress of nucleon-nucleus scattering analysis in the GeV region some results are presented. This is our first step for an in-medium search for transitions from the meson-nucleon into the quark-gluon sector using NA optical models.

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arXiv2001

Nucleon-Nucleon Optical Model for Energies to 3 GeV

Several nucleon-nucleon potentials, Paris, Nijmegen, Argonne, and those derived by quantum inversion, which describe the NN interaction for T-lab below 300$ MeV are extended in their range of application as NN optical models. Extensions are made in r-space using complex separable potentials definable with a wide range of form factor options including those of boundary condition models. We use the latest phase shift analyses SP00 (FA00, WI00) of Arndt et al. from 300 MeV to 3 GeV to determine these extensions. The imaginary parts of the optical model interactions account for loss of flux into direct or resonant production processes. The optical potential approach is of particular value as it permits one to visualize fusion, and subsequent fission, of nucleons when T-lab above 2 GeV. We do so by calculating the scattering wave functions to specify the energy and radial dependences of flux losses and of probability distributions. Furthermore, half-off the energy shell t-matrices are presented as they are readily deduced with this approach. Such t-matrices are required for studies of few- and many-body nuclear reactions.

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arXiv2000

Nucleon-Nucleon Optical Potentials \and Fusion of $π$N, KN, $ππ$ and NN Systems

Several boson exchange potentials, describing the NN interaction $T_\ell\le 300$ MeV with high quality, are extended in their range of applicability as NN optical models with complex local or separable potentials in r-space or as complex boundary condition models. We determine in this work the separable potential strengths or boundary conditions on the background of the Paris, Nijmegen-I, Nijmegen-II, Reid93, AV18 and inversion potentials. Other hadronic systems, $π$N, KN and $ππ$, are studied with the same token. We use the latest phase shift analyzes SP00, SM00 and FA00 by Arndt {\em et al.} as input and thus extent the mentioned potential models from 300 MeV to 3 GeV . The imaginary parts of the interaction account for loss of flux into direct or resonant production processes. For a study of resonances and absorption the partial waves wave functions with physical boundary conditions are calculated. We display the energy and radial dependences of flux losses and radial probabilities. The results lend quantitative support for the established mental image of intermediate elementary particle formation in the spirit of fusion.

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arXiv2000

The NN Phase Shifts <3 GeV and Resonance Features

Solutions SP00, SM00 and FA00 of nucleon-nucleon (NN) phase shift analyzes by Arndt et al. are used in optical model studies. The partial waves, single channels J.leq.7 and coupled channels J.leq.6, are scrutinized. The radial probability distributions and losses of flux are used to identify the known Delta and N* resonances as well as anticipated other structures. The energy interval extends to 3 GeV.

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