real CERN collisions in your browser — compute the mass, find the particles. then see how they found the Higgs.
This is real. 50,000 actual proton–proton collisions recorded by the CMS detector at CERN's Large Hadron Collider in 2011 (public domain, CERN Open Data, CC0). Each event is two muons; the tool computes their combined invariant mass — m² = (E₁+E₂)² − |p₁+p₂|² — entirely in your browser. Nothing is uploaded. Every spike is a real particle that existed for an instant and decayed into those two muons.
reading 50,000 real collisions…
Zoom to a particle
collisions read
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J/ψ (3.10 GeV)
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Υ (9.46 GeV)
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Z boson (91.2 GeV)
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Each peak is a real particle. The Z boson — a carrier of the weak nuclear force — sits at 91 GeV. You're seeing it in real data, in your browser.
The detector triggered on high-energy muon pairs, so light particles are rarer here; the J/ψ, Υ, and Z stand out clearly. Where's the Higgs? See tab ②.
This one is a simulation — and it says so honestly. The Higgs is ~700× rarer than the Z and decays mostly into messy jets, so it does not appear in the small public dimuon sample on tab ①. But the method is exact: ATLAS & CMS reconstructed the two-photon invariant mass and watched a peak rise at 125 GeV over a smooth background. This pane simulates that with faithful physics (signal = Gaussian at 125.1 GeV / 1.7 GeV detector resolution; background = falling QCD continuum; significance from a sideband fit — never from the truth). Collect collisions and watch it cross 5σ.
DISCOVERY
a new boson at 125 GeV · 5.0σ
the way the world found out — 4 July 2012
Significance
0.0σ
3σ evidence5σ discovery
data collected
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events in window
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background (sidebands)
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excess at peak
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peak position
— GeV
Significance grows as √(data): signal piles up faster than noise. The bump's width is the detector's blur — the real Higgs is ~1000× narrower.