Expected Glashow Resonance Event Rates in a Cubic-Kilometre Neutrino Detector

At 6.3 PeV an electron antineutrino can strike an atomic electron and form an on-shell W boson — the Glashow resonance — with a cross section far above the smooth deep-inelastic continuum. This paper computes the event rate such a resonance should produce in a cubic-kilometre detector exposed to the measured diffuse flux. With a resonant peak cross section of 1.500e-31 square centimetres, 1.673e+38 target electrons in half a cubic kilometre of water-equivalent volume, and a per-flavour diffuse level of E-squared flux 2.0 x 10^-8 GeV per square centimetre per second per steradian extrapolated to the resonance with index 2.5, the expected rate is 0.79 events per year over the downward half-sky, or about 7.9 events in ten years. A single candidate event has been reported in more than a decade of data. The naive extrapolation therefore overpredicts the observed yield severalfold, and the comparison quantifies how strongly the diffuse spectrum must soften, or the effective exposure must fall, toward the resonance energy. The study is computed from stated assumptions, not measured.