The Higgs mechanism, which consists of the Higgs field and its corresponding particles. In Einstein's formula, E=mc^2, the "m" is the inertial mass of the particle. In a sense, this mass is the essential quantity, which defines that at this place there is a particle rather than nothing. In early 1960, physicists had a powerful theory of electromagnetic interactions and a descriptive model of the weak nuclear interaction- the force that is at play in many radioactive decays and in the reactions which make sunshine.
Independent efforts by Robert Brout and Francois Englert in Brussels, Peter Higgs at the University of Edinburgh, and others lead to a concrete model known as Brout-Englert Higgs mechanism (BEH). The peculiarity of this mechanism is that it can give mass to elementary particles while retaining the nice structure of their original interaction.
The Large Electron-Positron Collider (LEP), which operated at CERN from 1989 to 2000, was the first accelerator to have significant reach into the potential mass range of Higgs Boson. In 1984, a few physicists and engineers at CERN were exploring the possibility of installing a proton-proton accelerator with a very high collision energy of 10-20 TeV in the same tunnel as LEP.
As Higgs Bosons are extremely rare, sophisticated analysis techniques are required to spot the signal events within the large background from other processes. Eager physicists analyzed the data as soon as it arrived. In the summer of 2011, there was a small excess in the Higgs decay for a mass of around 140 GeV.
In 2012, the energy of the LHC was increased from 7 to 8 TeV, which increased the cross-sections for Higgs Boson production.
The mass, the final unknown parameter in the Standard Model, was one of the first parameters measured and found to be approximately 125GeV. The heavier the particle, the stronger it's interaction with the Higgs field. This is one of the main predictions of the BEH mechanism in the standard model.
Over the next few years, analysis of the large Run 2 dataset will not only be an opportunity to reach a new level of precision in previous measurements but also to investigate new methods to probe Standard Model predictions. In the longer-term, another big-step in performance will be brought by High-Luminosity LHC, planned to begin operation in 2024.