Modification of the $\omega$-Meson Lifetime in Nuclear Matter

TL;DR

This study measures the in-medium modification of the $$-meson lifetime in nuclear matter, revealing a significant reduction and providing the first momentum-dependent $$N cross section estimate.

Contribution

It presents the first extraction of the momentum-dependent $$N cross section and quantifies the inelastic width and lifetime reduction of the $$ meson in nuclear matter.

Findings

Inelastic $$ width in nuclear matter is 130-150 MeV/c^2.

$$ meson lifetime is reduced by a factor of approximately 30.

First measurement of momentum-dependent $$N cross section (~70 mb).

Abstract

The photo production of $\omega$ mesons on the nuclei C, Ca, Nb and Pb has been measured using the Crystal Barrel/TAPS detector at the ELSA tagged photon facility in Bonn. The dependence of the $\omega$ meson cross section on the nuclear mass number has been compared with three different types of models, a Glauber analysis, a BUU analysis of the Giessen theory group and a calculation by the Valencia theory group. In all three cases, the inelastic $\omega$ width is found to be $130-150 \rm{MeV/c^2}$ at normal nuclear matter density for an average 3-momentum of 1.1 GeV/c. In the restframe of the $\omega$ meson, this inelastic $\omega$ width corresponds to a reduction of the $\omega$ lifetime by a factor $\approx 30$. For the first time, the momentum dependent $\omega$N cross section has been extracted from the experiment and is in the range of 70 mb.