The Higgs boson is an elementary particle within the Standard Model of particle physics. It belongs to a class of particles known as bosons. On July 4, 2012, CERN announced the formal confirmation that a particle "consistent with the Higgs boson" exists, since its signature was detected in the data with a very small probability of 0.00003%[4] (five sigma) of being produced by random fluctuations; however, particle physicists still need to verify that it is indeed the expected boson and not some other new particle.
The existence of the Higgs boson was predicted in 1964 to explain how the Higgs mechanism happens in nature. It is this which explains why other elementary particles have mass.[Note 2] While the Higgs mechanism is considered confirmed to exist, the boson itself - a cornerstone of the leading theory - had not been observed and its existence was unconfirmed. Its tentative discovery in 2012 may validate the Standard Model as essentially correct, as it is the final elementary particle predicted and required by the Standard Model which has not yet been observed via particle physics experiments.[5] Alternative sources of the Higgs mechanism that do not need the Higgs boson are also possible and would be considered if the existence of the Higgs boson were to be ruled out. They are known as Higgsless models.
The Higgs boson is named after British physicist Peter Higgs who was one of six authors in the 1960s who wrote the ground-breaking papers covering what is now known as the Higgs mechanism and described the related Higgs Field and boson. Technically, it is the quantum excitation of the Higgs field, and the non-zero value of the ground state of this field gives mass to the other elementary particles such as quarks and electrons through the Higgs mechanism. The Standard Model completely fixes the properties of the Higgs boson, except for its mass. It is expected to have no spin and no electric or color charge, and it interacts with other particles through the weak interaction and Yukawa-type interactions between the various fermions and the Higgs field.
Because the Higgs boson is a very massive particle and also decays almost immediately when created, only a very high energy particle accelerator can observe and record it. Experiments to confirm and determine the nature of the Higgs boson using the Large Hadron Collider (LHC) at CERN began in early 2010, and were performed at Fermilab's Tevatron until its closure in late 2011. Mathematical consistency of the Standard Model requires that any mechanism capable of generating the masses of elementary particles become visible at energies above 1.4 TeV;[6] therefore, the LHC (designed to collide two 7 TeV proton beams, but currently running at 4 TeV each) was built to answer the question of whether or not the Higgs boson actually exists.[7]
On 4 July 2012, the two main experiments at the LHC (ATLAS and CMS) both reported independently that they found a new particle with a mass of about 125 GeV/c2 (about 133 proton masses, on the order of 10-25 kg), which is "consistent with the Higgs boson". They acknowledged that further work would be needed to conclude that it is indeed the Higgs boson (meaning that it has the theoretically predicted properties of the Higgs boson) and to determine which version of the Standard Model it best supported if confirmed
