Reproducing Godfrey–Isgur

GIModel was built by reproducing S. Godfrey and N. Isgur, Phys. Rev. D 32, 189 (1985), table by table. This section describes that comparison: how it is organized, what agrees, where it differs, and why.

Two packages, one direction

The repository holds two Julia packages with a one-way dependency:

• GIModel (with its submodule QuarkModelTransitions) is the physics. It knows nothing about the paper's tables. You give it quark flavors and quantum numbers; it returns states and amplitudes.

• GIPaper (in GIPaper/) is the comparison. It holds the digitized paper data, maps each table row to a GIModel calculation, and writes the reports reproduced in this section.

GIPaper depends on GIModel, never the other way around. A reference row can therefore never steer a calculation: the model decides which state is which, and the comparison layer only assigns names.

Rules of the comparison

• The paper is the authority. Every reference number is transcribed from the published article with its page and table; the raw extraction is kept separately from the cleaned data (GIPaper/data/provenance/). The article itself is not distributed with the repository.

• No tuning toward the paper. The model uses the paper's Table II parameters and the literal Appendix A operators. Where the reproduction differs, the difference is reported, not fitted away.

• Fitted quantities are labeled. Only the constants the paper itself fits are refitted, in the same way: the strong-decay strengths and from the same two decays, and the charge-radius exponent   from the .

• Experimental inputs are pinned. Decay kinematics use a fixed table of PDG 2026 masses (GIPaper/data/mass_inputs/), with no fallback to model masses.

Running the comparison

From the repository root:

julia --project=GIPaper -e 'using Pkg; Pkg.instantiate(); Pkg.test()'
julia GIPaper/checks/run_all_spectrum_checks.jl     # spectra, all sectors
julia GIPaper/checks/audit_mixing_angles.jl         # same-J mixing angles
julia GIPaper/checks/audit_table_iii_mixings.jl     # isoscalar mixing
julia GIPaper/checks/reproduce_table_v.jl           # strong decays
julia GIPaper/checks/audit_table_vi_photon_decays.jl
julia GIPaper/checks/audit_table_vii.jl             # annihilation, leptonic, radii

Each script writes a Markdown report to GIPaper/reports/, stamped with the solver settings that produced it. The pages under Recorded reports are copies of those files, made when this documentation was built. bash scripts/verify_project.sh runs the whole chain together with both test suites.

To use the comparison layer in your own code:

using GIModel, GIPaper
params, mq = load_parameters_and_quark_masses(GIPaper.model_parameters_path())
reference = load_reference_spectrum(reference_spectrum_path("charmonium"))
rows = compare_reference(params, mq, reference; solver = OscillatorSolver())

Each row pairs a paper value with the model value and their residual.

What the paper computes, and where it is here

paper	content	reproduced by	report
Figs. 4–9, Table II	meson spectra in all flavor sectors	compute_spectrum	scorecard
Figs. 4, 7, 9 captions	same- mixing angles	spectroscopic mixing	mixing angles
Table III, Fig. 5	isoscalar annihilation mixing	compute_isoscalar_spectrum	Table III
Tables IV–V	strong decays	the paper's single-Gaussian reduction	Table V
Table VI	radiative transitions	PhotonEmission on solved waves	Table VI
Table VII	, , , weak decay constants, charge radii	annihilation operators on solved waves	Table VII

Results at a glance summarizes each comparison. Equations to code maps each equation of the paper to the code that implements it.