Baryon Resonance Analysis from MAID

TL;DR

This paper uses the MAID2007 isobar model to analyze pion electroproduction data, extracting resonance transition form factors and neutron form factors, and exploring their implications for charge densities and resonance structure.

Contribution

The study provides new Q^2 dependent transition form factors for multiple baryon resonances and neutron data, along with numerical parameterizations for use in other reactions.

Findings

Q^2 dependent transition form factors for several resonances

Numerical parameterizations for transition form factors

Initial results on empirical transverse charge densities

Abstract

The unitary isobar model MAID2007 has been used to analyze the recent data of pion electroproduction. The model contains all four-star resonances in the region below W=2 GeV and both single-Q^2 and Q^2 dependent transition form factors could be obtained for the Delta, Roper, D13(1520), S11(1535), S31(1620), S11(1650), D15(1675), F15(1680) and P13(1720). From the complete world data base, including also pi- data on the neutron, also Q^2 dependent neutron form factors are obtained. For all transition form factors we also give convenient numerical parameterizations that can be used in other reactions. Furthermore, we show how the transition form factors can be used to obtain empirical transverse charge densities and our first results are given for the Roper, the S11 and D13 resonances.