On July 4th, 2012, CERN held a seminar to present preliminary results from their ATLAS and CMS experiments. Both experiments observed a new particle in the mass region of around 125-126 GeV. This mass has been confirmed at a level of five sigma. These results are so far constant with the behaviour of the Higgs boson. However, CERN was very meticulous in stating that a “Higgs-like-particle” was discovered. Further data and analyses are still needed to cement the new particle as the Higgs boson. This pretty much summarizes the seminar, but it still leaves many questions for non-physics majors.
The Standard Model of particle physics, often abbreviated to SM in journals, explains electromagnetic, weak, and strong nuclear forces. Developed in the 1970s, the SM predicted and explained a countless number of experimental results. The final piece of the puzzle to verify the SM is the Higgs boson.
Generally, the public knows that the Higgs boson gives all other particles mass. This is entirely false. The Higgs field is what gives fundamental particles mass. The Higgs field is a non-zero quantum field that permeates the entire Universe. The Higgs field interacts with all particles with non-zero mass. The stronger the particles’ interaction with the Higgs field, the more massive the particle. Since the photon has zero interaction with the Higgs field, it is massless where as a top quark has a much stronger interaction with the Higgs field and, therefore, a much larger mass. Much like the how an excitation of the electromagnetic field produces a photon, an excitation of the Higgs field produces a Higgs boson. The only way to determine the existence of the Higgs field is from the detection of the Higgs boson.
With a mass of around 125 GeV, the Higgs-like-particle is 133 times more massive than a proton. A fundamental particle with a mass of around that of a neodymium atom is surely to be extremely unstable. It was only from the measurements of the Higgs-like-particle’s decay product was its final mass determined.
As was already mentioned, there were two experiments that presented these new results: ATLAS and CMS. The interesting thing about how the LHC operates is that the ATLAS and CMS collaborations are not allowed to talk to each other. They both share the particle accelerator but have very different equipment and analytical software. This allows a single institution to present independently verifiable results at one time and increase the confidence of their results.
Although these new findings are very exciting in the field of particle physics, there is still much more work to do before a true understanding of the Universe is achieved. The SM does not account some very important aspects of the Universe. Gravity, as explained in General Relativity, does not fit into the model. Neither does dark matter and dark energy, which makes up about 96% of the Universe from cosmological observations. Once the SM is experimentally verified, it’s going to be back to the drawing board to come up with a much more general theory of everything that encompasses these elements.
Leave a Reply