Electromagnetic transitions of excited baryons in a deformed oscillator quark model

TL;DR

This paper investigates electromagnetic transitions of excited baryons within a deformed oscillator quark model, providing tools for amplitude calculations and analyzing deformation effects, with insights into the Roper state discrepancies.

Contribution

It introduces a comprehensive method to compute transition amplitudes in a deformed oscillator quark model, linking multipole and helicity bases, and examines deformation effects on baryon transitions.

Findings

Deformation has a weak effect on transition amplitudes.

The model addresses sign and absolute value issues in amplitudes.

Challenges remain in reproducing the Roper state amplitude.

Abstract

We study electromagnetic transitions of excited baryons in a deformed oscillator quark model, where baryon excited states are described as rotational bands of deformed intrinsic states. We describe all necessary tools to compute transition amplitudes in multipole basis, which are then related to the commonly used helicity amplitudes. We pay a special attention on the sign of the amplitudes as well as their absolute values by computing the photon and pion couplings simultaneously. We have found that the effect of deformation on the transition amplitudes is rather weak. The difficulty in reproducing the empirical amplitude of the Roper state is discussed.