### Abstract

We present a relativistic and unitary approach to pion- and photon-nucleon scattering taking into account the πN, ρN, ωN, ηN, πΔ, Λ and K∑ channels. Our scheme dynamically generates the s- and d-wave baryon resonances N(1535), N(1650), N(1520) and N(1700) and as well as Δ(1620) and Δ(1700) in terms of quasi-local two-body interaction terms. The description of photon-induced processes is based on a generalized vector-meson dominance assumption which directly relates the electromagnetic quasi-local 4-point interaction vertices to the corresponding vertices involving the ρ and ω fields. We obtain a fair description of the experimental data relevant for the properties of slow vector mesons in nuclear matter. The resulting s-wave ρ- and ω-meson nucleon scattering amplitudes, which define the leading density modification of the ρ- and ω-meson spectral functions in nuclear matter, are presented. We find a repulsive energy shift for the ω meson at small nuclear density but predict considerable strength in resonance-hole like ω-meson modes. Compared to previous calculations our result for the ρ-meson spectral function shows a significantly smaller in-medium effect. This reflects a fairly small coupling strength of the N(1520) resonance to the ρN channel.

Original language | English |
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Pages (from-to) | 152-159 |

Number of pages | 8 |

Journal | Progress of Theoretical Physics Supplement |

Volume | 149 |

DOIs | |

Publication status | Published - jan. 1 2003 |

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### ASJC Scopus subject areas

- Physics and Astronomy (miscellaneous)

### Cite this

*Progress of Theoretical Physics Supplement*,

*149*, 152-159. https://doi.org/10.1143/PTPS.149.152