Accelerator X v4: Dirac Spinors, Color Coupling and Gauge-Invariant Response — Expanded Derivations and Reproducibility Study

Accelerator X v4 is an expanded theoretical and numerical research prototype covering Dirac spinors, SU(3) color coupling, a finite-time external-field toy model, and the electromagnetic current correlator and partonic R ratio. The volume states its objectives, gives derivations, records numerical benchmarks and noise sensitivity, and includes references. No experimental data were analyzed; no new QCD prediction or detector performance is claimed. The earlier Accelerator X v3 detector concept and derivative-signatures note are included as historical appendices and separate files. This record is separate from, and references, Zenodo record 23621011. ChatGPT assisted with mathematical exposition, coding, review, and document preparation. File guidance: use Accelerator_X_v4_Expanded_Study_Corrected.pdf and Accelerator_X_v4_Reproducibility_Package_Corrected.zip for the corrected edition. The retained earlier v4 draft PDF and ZIP without the Corrected suffix contain a flattened Yang–Mills equation; the separately named v3 and derivative-signatures PDFs are historical originals.