ALP-ttbar Toy MC v1.2: Post-registration Results for Hit-Pattern Consistency and a Lifetime Scan of the Photon-Conversion Veto (companion to arXiv:2610.38932)

Post-registration results (v1.2) of a personal, numpy-only toy Monte Carlo written after reading arXiv:2610.38932 (J. Alimena et al., "Hunting for Long-Lived ALPs in Top Events via Displaced Dielectron Pairs at the LHC"). v1.1 found that, for the lightest ALPs, the material veto against photon conversions depends mainly on non-Gaussian tails of the vertex resolution. v1.2 tested, under a public preregistration frozen before any v1.2 code was run, whether a hit-pattern consistency requirement removes this dependence. It does not: at 17 MeV the least favourable case improves only from about 64x to 55x loss in reach, outside the preregistered prediction (13-43x), which is therefore refuted. The other three predictions (little change for Gaussian resolution, little change at 100-200 MeV, 17 MeV most affected at ctau = 0.1, 1 and 10 mm) are confirmed. The v1.1 conclusion stands. The report lists the detector-level studies needed next. Files: 3-page report (PDF) and a complete snapshot (zip) with code, Figures 1-5 and printed numbers; ./run_all.sh reproduces everything with fixed seeds. Disclaimer: personal project, not affiliated with the paper's authors or the CMS Collaboration. Kinematics are parametrised and detector numbers assumed; only qualitative trends and ratios are meaningful.