Detection of Higgs bosons at the Large Hadron Collider
|Large Hadron Collider route. Image by Maximilien Brice (CERN) - via Wikimedia Commons|
These Higgs bosons last only a very short time before being converted into other particles and this occurs in one of several ways, producing different characteristic types of particles each time. It is actually these other sets of particles that have been detected (rather than the Higgs bosons themselves) e.g. at the ATLAS & CMS project's array of detectors at CERN. From knowledge of the characteristic sets of (Higgs boson-related) particles and the detection of several types of these particles, it was inferred that Higgs bosons had been created. The same conclusion was reached by investigators in two separate international groups of scientists, involved in the ATLAS and the CMS projects, at CERN in July 2012. In each of the detection curves in the CMS & ATLAS detector graphs on the right of this image can be seen small deviations (at around 125-126 GeV on the X axis) of the observed data from the dotted line (which represents the predicted results if Higgs bosons did not exit). The deviations were highly likely to be due to particles resulting from Higgs bosons that had been created and then had rapidly decayed by the production of two gamma ray photos e.g. in the first way illustrated in the left.
|From web resource of Bojan Golli, University of Ljubljana.|
In the diagram above, the first i.e. the upper diagram shows the proton-proton collision (i.e. "event") resulting in a Higgs boson, which only exists for less than nanosecond (a billionth of a second) and which then decays into two gamma ray photons. The lower diagram illustrates the Higgs boson rapidly decaying into two Z bosons, each of which then, almost instantly, decays into two charged leptons. Z bosons can each decay into two electrons or two muons. Both types of leptons can be fairly easily detected by the detectors at the LHC.
|Image from Berkeley Lab website.|
The CMS and ATLAS results were at the level of approximately "5-sigma" (5 standard deviations), i.e. a sufficiently high likelihood (99.99994%) of being the correct result and a sufficiently low probability (0.00006% i.e. less than 1 in a million) of being just a random statistical fluctuation in the data i.e. an artefact.
Several other Higgs boson decay type are believed to occur, such as the decay into two photons, as indicated by the green projections shown in the header image at the top of this web page. Another predicted type of decay is that simulated in this image below, in which a Higgs boson decays into two jets of hadrons and two electrons.
|By Lucas Taylor (http://cdsweb.cern.ch/record/628469) via Wikimedia Commons|
Essentially, the detection of the Higgs bosons (albeit indirectly) by the CMS and ATLAS projects, of the energy that was predicted, provided the necessary evidence for the existence of the Higgs field and, in turn, also the Higgs Mechanism for the acquisition of mass by force-carrying particles.