Interaction of vector mesons with baryons and vectors in the nuclear medium

TL;DR

This paper reviews recent theoretical developments on vector meson interactions with baryons and nuclei, highlighting dynamically generated resonances, mixing effects, and implications for nuclear reactions involving charm and $J/\psi$ states.

Contribution

It introduces a unified hidden gauge formalism for vector meson interactions, revealing new baryon resonances and their potential experimental signatures.

Findings

Identification of a hidden charm baryon state around 4400 MeV.

Prediction of a large in-medium width for $K^*$ mesons.

Proposal of transparency ratio measurements for $J/\psi$ photoproduction.

Abstract

In this talk we present a short review of recent developments concerning the interaction of vector mesons with baryons and with nuclei. We begin with the hidden gauge formalism for the interaction of vector mesons, then review results for vector baryon interaction and in particular the resonances which appear as composite states, dynamically generated from the interaction of vector mesons with baryons. New developments concerning the mixing of these states with pseudoscalars and baryons are also reported. We include some discussion on the $5/2^+$ $\Delta$ resonances around 2000 MeV, where we suggest that the $\Delta(2000)5/2^+$ resonance, which comes in the PDG from averaging a set of resonances appearing around 1700 MeV and another one around 2200 MeV, corresponds indeed to two distinct resonances. We also report on a hidden charm baryon state around 4400 MeV coming from the interaction of vector mesons and baryons with charm, and how this state has some repercussion in the $J/\psi$ suppression in nuclei. The interaction of $K^*$ in nuclei is also reported and suggestions are made to measure by means of the transparency ratio the huge width in the medium that the theoretical calculations predict. The formalism is extended to $J/\psi$ interaction with nuclei and the transparency ratio for $J/\psi$ photoproduction in nuclei is studied and shown to be a good tool to find possible baryon states which couple to $J/\psi N$.