The width of the omega meson in the nuclear medium

TL;DR

This paper calculates the increased width of the omega meson in nuclear matter, considering medium modifications and various decay and interaction processes, showing a significant broadening at normal nuclear density.

Contribution

It provides a detailed theoretical evaluation of the omega meson width in nuclear medium, incorporating medium-modified propagators and multiple interaction channels.

Findings

Omega width reaches 129 MeV at nuclear saturation density for omega at rest.

Width increases to about 200 MeV at 600 MeV/c momentum.

Main contribution from omega N to pi pi N and pi NN processes.

Abstract

We evaluate the width of the $\omega$ meson in nuclear matter. We consider the free decay mode of the $\omega$ into three pions, which is dominated by $\rho \pi$ decay, and replace the $\rho$ and $\pi$ propagators by their medium modified ones. We also take into account the quasielastic and inelastic processes induced by a vector-baryon interaction dominated by vector meson exchange, as well as the contributions coming from the $\omega \to K \bar K$ mechanism with medium modified $K$, $\bar K$ propagators. We obtain a substantial increase of the $\omega$ width in the medium, reaching a value of $129 \pm 10$ MeV at normal nuclear matter density for an $\omega$ at rest, which comes mainly from $\omega N \to \pi \pi N, \omega N N \to \pi NN$ processes associated to the dominant $\omega \to \rho\pi$ decay mode. The value of the width increases moderately with momentum, reaching values of around 200 MeV at 600 MeV/c.