Sunday, December 18, 2011

CERN announces possible evidence for the Higgs Boson

On Tuesday, December 13th, the European Center for Nuclear Research (CERN) announced that two competing teams have possibly detected the hypothetical Higgs Boson, the last of the elementary particles predicted by the Standard Model remaining to be uncovered. The possible new discovery was made at the Large Hadron Collider (LHC), the largest particle accelerator in existence. With a circumference of 27km (17 miles), the LHC is able to accelerate twin proton beams up to a speed of 99.999 the speed of light, creating an impact energy of 14.7 TeV (Terra Electron Volts). One of the prime reasons for the construction of the LHC was to look for the Higgs Boson, which until the construction of the LHC, had a predicted energy limit above the capability of the largest particle colliders of the time.

The announcement was made based on the works of two competing teams working at two separate detectors located at the LHC. One at the ATLAS (A Toroidal LHC ApparatuS) and the other at the CMS (Compact Muon Solenoid), both of which are considered the general purpose detectors of the LHC, with the ATLAS fittingly being the larger of the two. The team at ATLAS found an excess of reactions stemming from the range of 125-6 GeV (Giga Electron Volts) while the CMS team found a similar excess at 124 GeV. When combined with other data from previous experiments, this gives us a certainty of 95% of the Higgs Boson being limited to the range of 115-130 Gev. To give you an example of what these numbers mean, 125 GeV is 133 times the mass of a proton, one of the two particles that make up the nucleus of an atom.

The Higgs Boson itself is far to short lived to be detected directly. Instead, it can be infered based on particles formed from its decay inside the detectors at the LHC. Because of this and the mess of other particles formed during these intense collisions, it takes both large amounts of computing power as well as huge numbers of collisions. In the case of the Higgs, an excess of two muons and two neutrinos, which come from, in turn, two W bosons. Because these kinds of reactions can be formed by random background noise, physicists must be careful to rule out all possible causes before settling upon the Higgs Boson as the source.

A simulated computer model for the reaction caused by a Higgs Boson.

It should be noted that CERN did not confirm that the Higgs Boson had been discovered, but that further evidence must be uncovered before it can be safely said that the Higgs Boson exists. Until then, this new data only makes the existence of the particle much more likely while reducing the energy ranges that are likely to harbor the particle. If the Higgs does exist, it is expected to be confirmed sometime in 2012 if current predictions are accurate.

The importance of the discovery of the Higgs Boson is hard to understate. It has often been referred to as the "God Particle" in the media, much to the chagrin of many physicists. This is due to the book of the same name written by physicist Leon Lederman who has been quoted as stating that the Higgs Boson is:

so central to the state of physics today, so crucial to our understanding of the structure of matter, yet so elusive

As well as jokingly following this with:

the publisher wouldn't let us call it the Goddamn Particle, though that might be a more appropriate title, given its villainous nature and the expense it is causing.

The Higgs Boson was predicted by three independent groups at nearly the same time in 1964. Eventually the particle was named after one of these individuals who has been given the credit for fleshing out the concept the most, Scottish physicist Peter Higgs. The Higgs Boson is the quanta (smallest unit of energy) for the Higgs Field, which would grant mass to other particles. One of the simplest ways to describe the Higgs Field was written by David J. Miller. He described the process as:

Imagine that a room full of physicists chattering quietly is like space filled with the Higgs field. A well-known scientist walks in, creating a disturbance as he moves across the room and attracting a group of admirers with every step.

This increases his resistance to movement. In other words, he acquires mass, just like a particle moving through the Higgs field. Now imagine if, instead of a well-known scientist entering, somebody started a rumour.

As the rumour spreads throughout the room, it creates the same kind of grouping, but this time it’s the scientists grouping together.

In this analogy, these groups are the Higgs bosons. If we find these groups, we can prove the Higgs field exists and thus explain the origin of mass.

The Higgs Boson also would be responsible for the symmetry breaking of the ElectroWeak Force, which is a combination of the Electromagnetic and Weak Nuclear forces and would explain why the mediating particle of the Electromagnetic (the Photon) is mass-less while the ones for the Weak Nuclear (the W and Z bosons) has a mass. It has also been hypothesized as one possible cause for the Inflationary period of the universe, when the young and hot cosmos expanded in volume by a factor of 10 to the 78th power between the times of 10 to the -36th seconds and either 10 to the -33rd or -32nd seconds. Though the Higgs Boson's part in Inflation is still hotly debated.
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