Mesons in Nuclei: eta and omega mesons

TL;DR

This paper reviews recent experimental efforts to detect in-medium modifications of mesons within nuclei, focusing on omega, eta, and pi0 mesons, using various advanced detector setups and nuclear targets.

Contribution

It presents new experimental analyses and searches for mesic states in light nuclei, utilizing data from multiple facilities and detector configurations.

Findings

Omega meson line shape sensitive to background subtraction

Search for eta-mesic 3He using photoproduction data

Ongoing search for 4He-eta bound state with high-statistics measurements

Abstract

Data on the photoproduction of omega mesons on nuclei have been re-analyzed in search for in-medium modifications. The data were taken with the Crystal Barrel(CB)/TAPS detector system at the ELSA accelerator facility in Bonn. The extracted omega line shape was found to be sensitive to the background subtraction. In experiments at the tagged photon facility of the Mainz MAMI accelerator photoproduction of mesons from light nuclear targets (deuteron and 3He) has been studied. The experiments used the combined Crystal Ball/TAPS setup in Mainz. Measurements of eta- and pi0-photoproduction off a liquid 3He-target have been used for the search for the formation of eta-mesic 3He. The installation of the WASA detector at COSY opened a unique possibility to search for the 4He-eta bound state with high statistics and high acceptance. We are conducting a search via an exclusive measurement of the excitation function for the dd -> 3He p pi- reaction.