Unitary Isobar Model - MAID2007

TL;DR

MAID2007 is a comprehensive unitary isobar model designed to analyze pion photo- and electroproduction data, incorporating resonance and background contributions, and providing detailed resonance amplitude extractions for energies below 2 GeV.

Contribution

It introduces a unified framework with unitarized background and resonance terms, enabling consistent analysis and prediction of pion production observables.

Findings

Extracted helicity amplitudes for key resonances

Analyzed world data with single-energy and global fits

Validated model predictions against experimental data

Abstract

The unitary isobar model MAID2007 has been developed to analyze the world data of pion photo- and electroproduction. The model contains both a common background and several resonance terms. The background is unitarized according to the K-matrix prescription, and the 13 four-star resonances with masses below 2 GeV are described by appropriately unitarized Breit-Wigner forms. The data have been analyzed by both single-energy and global fits, and the transverse and longitudinal helicity amplitudes have been extracted for the four-star resonances below 2 GeV. Because of its inherent simplicity, MAID2007 is well adopted for predictions and analysis of the observables in pion photo- and electroproduction.