Photo- and electroproduction of $K^{+}\Lambda$ with unitarity-restored isobar model

TL;DR

This paper presents an upgraded isobar model for kaon photo- and electroproduction on protons, incorporating higher-spin exchanges, energy-dependent resonance widths, and longitudinal couplings to better fit experimental data across all kinematic regions.

Contribution

The model introduces energy-dependent resonance widths and includes longitudinal couplings, providing a more accurate and comprehensive description of kaon production processes.

Findings

Model fits experimental data well across all kinematic regions.

Inclusion of longitudinal couplings improves electroproduction description.

Resonance selection aligns with previous analyses and Bayesian models.

Abstract

Exploiting the isobar model, kaon photo- and electroproduction on the proton in the resonance region comes under scrutiny. An upgrade of our previous model, comprising higher-spin nucleon and hyperon exchanges in the consistent formalism, was accomplished by implementing energy-dependent widths of nucleon resonances, which leads to a different choice of hadron form factor with much softer values of cutoff parameter for the resonant part. For a reliable description of electroproduction, the necessity of including longitudinal couplings of nucleon resonances to virtual photons was revealed. We present a new model whose free parameters were adjusted to photo- and electroproduction data and which provides a reliable overall description of experimental data in all kinematic regions. The majority of nucleon resonances chosen in this analysis coincide with those selected in our previous analysis and also in the Bayesian analysis with the Regge-plus-resonance model as the states contributing to this process with the highest probability.