Predictions — mH, sin2 (thetaW) BCT Letter 6: The Higgs Boson Mass and Electroweak Precision Observables from BCT Vacuum Geometry with Zero Free Parameters

The Higgs boson mass mH = 125.25 ± 0.17 GeV and the electroweak mixing angle sin2θW = 0.23122±0.00003 are among the most precisely measured parameters of the Standard Model, yet no framework derives their values from first principles. Within the Body-Centred Tetragonal (BCT) Superfluid Lattice Model, both are consequences of the vacuum void geometry and the D4 root lattice structure. The Higgs mass emerges from the criticality condition λ(mP ) = 0 applied to the BCTderived top quark mass mt = 172.0 GeV, yielding mH = 125,216 MeV (−0.027% error). The weak mixing angle is derived from the ratio of void couplings: sin2θW = α0/(4rtet) = 0.2312 (−0.002% error). The W boson mass mW = 80,357 MeV (−0.009%), the Z boson mass mZ = 91,188 MeV (+0.002%), and the electroweak vacuum expectation value v = 246.2 GeV are all derived quantities. The global electroweak fit achieves χ 2 /dof = 0.95 with zero free parameters, compared to the Standard Model fit of ∼ 1.05 with five free parameters.