Symbolic Amplitudes for Light Baryons

$N^{*}$ Resonances at GlueX

Note

This repository is under active development.

We are doing amplitude analysis and Partial Wave Analysis (PWA) with CAS-assisted model building, a technique employed in the ComPWA project.

• First demonstration example: $\gamma p \to \eta \pi^0 p$, with $N^{*}$ resonances in

  • the $p\eta$ subsystem, and
  • the $p\pi^0$ subsystem.

• Main physics target: $\gamma p \to K^+ \pi^0 \Lambda$, with resonance contributions in:

  • the $\Lambda K^+$ system ($N^{*}$),
  • the $\Lambda \pi^0$ system ($Y^{*}$),
  • the $K^+ \pi^0$ system ($K^{*}$).

Current long-term plan: This research project focuses on developing and applying amplitude models to analyze data from the GlueX experiment, specifically targeting $N^{}$ and $Y^{}$ resonances.

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Warning

Scope and physical interpretation

The amplitude models in this repository are symbolic, CAS-assisted prototypes developed primarily in an s-channel decay-amplitude mindset.

While reactions such as $\gamma p \to \eta \pi^0 p$ and $\gamma p \to K^+ \pi^0 \Lambda$ are used as demonstration channels, the current implementations:

• model sequential s-channel decay chains,
• do not include a realistic treatment of photoproduction dynamics, such as t-channel (or u-channel) exchange mechanisms, Reggeized exchanges, or energy-dependent production amplitudes,
• are therefore not physically realistic descriptions of GlueX photoproduction, which is dominated by t-channel processes at GlueX energies.

This work should be understood as a proof-of-concept and technical foundation for automated amplitude construction and visualization, providing a reproducible basis for future extensions toward realistic production–decay hybrid models and multi-channel hadron-spectroscopy analyses.