Dilepton Decay of Low-mass $\rho$ Mesons

TL;DR

This paper analyzes dilepton mass spectra from $ ho$ meson decays in proton reactions, comparing experimental data with theoretical models to understand the vector meson dominance and the $ ho$ spectral function.

Contribution

It provides a detailed comparison of experimental data with GiBUU model predictions, highlighting the importance of the $ ho$ spectral function in interpreting VMD models.

Findings

The subtraction procedure was validated.

Mass spectra depend on the $ ho$ spectral function.

Conclusions on VMD versions require spectral function knowledge.

Abstract

The HADES collaboration has extracted dilepton mass spectra for $\pi^-$ induced reactions on the proton from a comparison of data taken on C and CH$_2$ targets. The spectra were interpreted in terms of different versions of vector meson dominance. Here we present results obtained from the theory and generator GiBUU. We first check the subtraction procedure used and then discuss the obtained mass spectra for the proton target. We point out that any conclusions on the version of VMD requires the knowledge of the $\rho$ spectral function in the interesting mass region.