$N^* (1520)$ transition form factors from dispersion theory

TL;DR

This paper presents a model-independent dispersive approach to calculate the electromagnetic transition form factors of the $N^*(1520)$ resonance, relating space-like and time-like regions using experimental data and pion rescattering effects.

Contribution

It introduces a novel dispersive framework for $N^*(1520)$ TFFs that combines space-like data with pion rescattering, enabling predictions in the time-like region.

Findings

Dispersive relations connect space-like and time-like TFFs.

Predictions for $N^*(1520)$ TFFs in the time-like region.

Framework validated with existing experimental data.

Abstract

The electromagnetic transition form factors (TFFs) of the nucleon provide important information on the internal structure of hadrons. A model-independent dispersive calculation of the electromagnetic TFFs $N^{*}(1520)\to N$ at low energies is presented. Taking pion rescattering into consideration, we derived dispersive relations for the $N^{*}(1520)\to N$ TFFs that relate space-like and time-like regions from the first principles. Based on the space-like data from JLab and hadronic data measured by HADES, we make predictions for TFFs in the time-like region. Our predictions can be tested in future experiments (e.g. HADES).