Absorption of the Omega and Phi Mesons in Nuclei
C. Djalali 1*, M. Wood 2, M. Paolone 1, R. Nasseripour 3, D. Weygand 4
1 University of South Carolina- Physics Dept, Columbia, SC, USA
2 Canisius College, Buffalo, NY, USA
3 George Washington University, Washington DC, USA
4 Thomas Jefferson National Accelerator Facility, Newport News VA, USA
The properties of hadrons, such as their masses and widths, are predicted to be modified in dense and/or hot nuclear matter. Particular attention has been given to the modifications of vector-meson properties in ordinary nuclear matter where chiral symmetry is predicted to be partially restored due to a change in the quark condensate. Different models predict relatively large measurable changes in the mass and/or the width of these mesons. The e+e− decay channel of these mesons has negligible final-state interactions (FSI), providing an ideal tool to study their possible in-medium modifications Due to its short lifetime, the rho meson has a substantial probability of decaying in the nucleus and its study has been previously reported.
Due to their long lifetimes, the omega and phi mesons are ideal candidates for the study of possible modifications of the in-medium meson-nucleon interaction through their absorption inside the nucleus. These mesons were photoproduced from 2H, C, Ti, Fe, and Pb targets at the Thomas Jefferson National Accelerator Facility. Nuclear transparencies ratios were derived in the e+e− channel. These ratios indicate larger in-medium widths compared with what have been reported in other reaction channels. The absorption of the ω meson is stronger than that reported by the CBELSA-TAPS experiment. These results are compared to recent theoretical models. The next round of experiments looking at the medium modification of vector mesons will also be discussed.
Transparency ratios, normalized to C, versus A for the omega (a) and phi (b) mesons. The curves are Glauber calculations with various meson-nucleon cross sections.