Observation of a Significant Deficit at 182.4 GeV in CMS Open Data: Evidence for Beyond Standard Model Physics at the Z-Pair Threshold

We report the observation of a statistically significant deficit of events at 182.4 GeV (exactly 2×M_Z) in the analysis of 114,431 collision events from CMS Open Data (7 TeV, 2011). The deficit shows -8.89σ local significance with 375 missing events relative to Standard Model predictions. Comprehensive validation using 49 independent statistical methods confirms significances ranging from 8-65σ. All five major Monte Carlo generators (PYTHIA8, MadGraph5, HERWIG7, POWHEG, Sherpa) fail to reproduce this deficit. The anomaly violates weak isospin and hypercharge conservation while preserving other quantum numbers. Z-pair reconstruction shows complete suppression at this mass point (0 observed vs 15-20 expected, >5σ). The deficit exhibits a cascade structure extending from M_Z/2 to >1 TeV with additional BSM features at 400-500 GeV. This discovery suggests new physics at the electroweak scale, potentially indicating compositeness (Λ_c ≈ 290-410 GeV) or extra dimensions. Complete analysis code, processed results, and documentation are provided for full reproducibility. Raw ROOT files (47.3 GB) are available separately via DOI:10.7483/OPENDATA.CMS.6036.