CERN Higgs Boson Discovery Seminar/Lecture





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Published on Jul 4, 2012

Director General of CERN, Rolf Heuer, and the head scientists from the ATLAS and CMS at CERN in Geneva gives a conference and lecture on the discovery of the Higgs Boson at a rest mass energy of 126.5 GeV at a 4.9 confidence level (the maximum limit being 5) . This confidence level, in experimental physics, constitutes a discovery with 98% probability of certainty, making it the first true discovery of the Higgs Boson in human history.
The bump in the energy spectrum observed at 125GeV contained a bump known with 99.9997% certainty.
Since the observed Higgs mass lies between 115--130 GeV, this rules out the minimal Standard Model Higgs expected at 141 GeV. This means that it is a Higgs-like Boson!

The Higgs seen at 125.5 GeV is at 3.8 sigma confidence level for the 4-lepton channel, the so-called "Golden Channel" of 4-leptons, created by the Higgs decaying into 2 Z-Boson Intermediates and those decaying into 4-leptons, 2-leptons per Z-Boson. These Leptons are Muons, detected by the Compact Muon Solenoid (CMS) detector.
The same channel leads to a 3.2 confidence level with the look elsewhere effect taken into account.

The Z-boson and photon channel integrated gives 5 sigma, the highest level possible with no significant errors.

The W-channel gives 1.5 sigma confidence channel, so it is definitely meeting the double blind trials of a "Well-behaved" Higgs. Its a good boson for a Higgs candidate, it does as the Higgs should.

The discovery from the various decay channels detected, the Boson discovered was most likely a "New Boson" or at least a "Higgs-like" Boson at 125.3 +/- 0.6 GeV at 4.9 sigma confidence level. This makes it a significant scientific discovery.

The minimalist models of the Standard Model predict that the Higgs mass ought to be at about 141 GeV. So a 125 GeV model is a problem, theoretically, and leads to many problems like an unstable vacuum at energies much lower than the Planck scale. The Physics obtained from this discovery will most likely be new physics that will help us understand electroweak symmetry breaking but it also seems more and more likely that we are beginning to observe the effects of Supersymmetry for the first time aswell.

Supersymmetric models are our best bet in this situation for the Boson discovered, for which it behaves like the Higgs Boson should.

The Boson Detected with the square root of its action being at 8 TeV (8 Trillion Electron Volts) has a Lagrangian Density of about 5 femtobarns (5 x 10^-9 barns), since 1 barn = 100 femtometers^2 this means the Higgs cross-section is only 5 x 10^-43 meters squared.

Experimentally however it is a great triumph and a powerful discovery, the data obtained from this event through rigorous experimental and computational techniques will be studied and scrutinized as normal but now we know where to go from here. The Boson is here to stay and the work is going to begin on mastering it. Considering that it was found in the last energy region searched, this last piece of the jigsaw is deservedly put in its rightful place. The full picture will change everything.


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