July 4 is the 10th anniversary of the discovery of the Higgs boson, also known as God’s particle. After a search of more than 40 years, the particle was discovered in experiments on the Large Hadron Collider (LHC) at European Organization for Nuclear Research (CERN) near Geneva, Switzerland on July 4, 2012. 


Considered one of the most important scientific discoveries of the modern era, the Higgs boson provides evidence for the Standard Model of Physics, which describes how various particles make the universe. 


The Standard Model


The Standard Model of particle physics describes how the world is constructed. We know that all matter consists of particles, which are the building blocks of nature. These particles are governed by four types of forces — gravitation, electromagnetism, the weak force and the strong force. The Standard Model unites the building blocks of nature and three of these four forces (gravitation remains outside the model). 


For the Standard Model to be correct, the Higgs boson must exist. Without the Higgs boson, the Standard Model would fail. That is why it is known as the God particle.


The Higgs boson


Based on their characteristics, all subatomic particles belong to two broad categories: bosons and fermions. Bosons are named after the Indian physicist Satyendranath Bose who, along with Albert Einstein, proposed a theory on the characteristics of such particles. 


There are several types of bosons, and the Higgs boson is one of them. This particle is named after the scientist Peter Higgs, who won the Nobel Prize for Physics in 2013, jointly with Francois Englert. In 1964, independently of each other, Peter Higgs and the team of Francois Englert and Robert Brout (who died in 2011) had proposed a theory that there is a particle that explains why other particles have a mass. This particle is the Higgs boson.


The Connection


The Standard Model would only work if particles did not have mass. But most particles do have mass, which is why all matter has mass. How could the Standard Model be correct then?


“This is where Englert, Brout and Higgs entered the stage with the ingenious mechanism for particles to acquire mass that managed to rescue the Standard Model,” the Nobel Prize official website says.


According to physics, space is filled with many invisible fields, such as gravitational field, electromagnetic field etc. One of these is known as the Higgs field, and was proposed by Englert, Brout and Higgs. All particles acquire mass only if they come into contact with the Higgs field. If the Higgs field disappeared, all matter would cease to exist.


The Higgs particle is a vibration of the Higgs field. But until 2012, it existed only in theory. It had not yet been actually detected.


The Discovery


The CERN website says the Higgs boson can't be “discovered” by finding it somewhere. It has to be created in a particle collision. But once created, it quickly decays into other particles. Scientists look for traces of these particles in data collected by the detectors. 


The challenge is that the Higgs boson only appears in about one in a billion LHC collisions. But careful statistical analysis of enormous amounts of data uncovered the particle's faint signal in 2012.


On July 4, 2012, the ATLAS and CMS collaborations announced the discovery of a new particle. This particle behaved like the proposed Higgs boson should. But was it really the Higgs boson? By examining more data, scientists concluded in March 2013 that, indeed, some kind of Higgs boson had been discovered, according to CERN. 


Christoph Paus, the MIT physicist who co-led the effort to detect the particle, is quoted as saying on the MIT website: “How could we be sure that it was the Higgs boson and not something else? It certainly looked like the Higgs boson, but our vision was quite blurry. It could have turned out in the following years that it was not the Higgs boson. But as we now know, with so much more data, everything is completely consistent with what the Higgs boson is predicted to look like, so we became comfortable with calling the narrow resonance not just a Higgs-like particle but rather simply the Higgs boson.”