TheMillerCircle.org

Higss boson detection?
(Taken from G. Aad et al, Physical Review Let, 108, 2012). Detection based on decay into two photons causing a bump in the decay rate at 125 GeV (Giga electron Volts)

With the apparent discovery of the Higgs boson (not absolutely certain yet), using the Large Hadron Collider (LHC) located near Geneva Switzerland (but also extending into French territory), particle physicists celebrated their achievement and left no doubt that the largest particle accelerator in the world had proved its worth, by discovering the Higgs boson and validating  the very reason for its construction. The LHC is under the control of CERN, originally derived from the French “Conseil Européen pour la Recherche Nucléaire,” or in its anglicized form, the “European Council for Nuclear Research.” Those associated with this giant collider can properly lay claim not only to the most powerful accelerator in the world, but also display the swagger that comes from a European facility, rather than one residing in the United States. The American Superconducting Super Collider—the largest basic science project in world history at the time— was cancelled by Congress in 1993 as a result of the imminent takeover of Congress by the Newt Gingrich Republicans and their “Contract on America.” This abandoned project lies as a giant hole in Texas, right outside of Dallas. As Congress cancelled the project they had to spend an extra $1 billion, just to seal the hole and shut the project down. It is an underground monument to the end of public support for physicists who had been the darlings of Congress, from the time they built the atomic and hydrogen bombs until they cancelled the Super Collider project very abruptly, throwing some 2000 physicists out of work. Had it been completed, it very likely would have provided the technology to detect the Higgs boson some years ago. Some of the physicists who lost employment when the Super Collider was cancelled,  moved on to Wall Street and produced the mathematical models that continue to provide uncertainty about the stability of Wall Street and its trading practices. But, we digress.

The LHC is a marvel of technology, with two 27 km rings of superconducting magnets, that move particles close to the speed of light in opposite directions in each of two rings of magnets. The superconducting magnets that accelerate the flow of particles (usually protons) are cooled to -271 degrees Centigrade by liquid helium, which circulates within the structure. At certain points along the accelerator path, magnets are used to bring the particles together in opposing streams at positions where detectors are placed to record the high speed collisions and detect various types of particle species that emerge.   As a result of this particle train wreck, multiple particles are generated and separate detectors are used to capture images of the complex decay events.  As a result of the Higgs boson experiment and the many similar studies that will follow, particle physicists are dreaming about a far more complete picture of the structure of the atom, the composition of the universe and the forces that interact to make these structures behave in a rational way when we make reactions in  a test tube, or use them in ordinary, everyday life, expecting consistent reactions and results. If we had solved the atomic structure of the atom first, we probably would never have put anything in a test tube because our assumption would be that nothing simple could possibly work. At the supra-atomic  level things seem quite predictable, but at the sub-atomic level it is a picture of chaos taking place within a massive, largely unoccupied space. The discovery of the Higgs boson may lead to a complete description of the structure of the atom and provide an account of the major forces  that created the universe, including such things as dark matter, though at the moment this is far from certain and no particle physicist would be surprised if additional forces or sub-atomic particles are revealed by future operations of the LHC. Many scientists remain cautious about over-exuberance based on the present results, because if the Higgs boson is for real, one should see evidence for it from several different detectors, as the Higgs boson can decay into several different types of particles.  The results illustrated in the figure were based on the detection of a Higgs boson decaying into two photons. And scientists define these bumps on the basis of the number of standard deviations above the background, hoping to see events that in the range of 3 to 5 standard deviations above the background.  For the next several years, we can expect the results of the LHC to appear on the front pages of our newspapers and occasionally be inserted  above the fold. If one can accept the Standard Model of the atom, for which the Higgs boson may be the last piece of the puzzle to fall into place, why can’t we accept global climate change, for which we do not require a particle accelerator to visualize what is going on around us within our little blue planet?

Physicist Sean Carroll’s website illustrates what one might call a “photograph” of a Higgs boson decay process, illustrated in the accompanying figure. This figure plots the number of events recorded (events/GeV=Giga electron volts) as a function of the mass of the particle (also measured in GeV). The deviation attributed to the Higgs boson data is compared with a Higgs simulation (dotted red line) at 120 GeV. The original article was published in Physical Review Letters, in March 2012. The paper itself is six pages long, but the list of authors, which follows the references, is fifteen pages long with many authors listed on a single line, acknowledging that it takes a village to find the Higgs boson: in this case, it’s a global village. Most Physics departments around the world have one or more physicists working on one aspect or another of the LHC project.

If the discovery of the Higgs boson is secured by additional experimental studies, it seems likely that when Obi Wan Kenobi of Star Wars fame claimed to have detected a disturbance in the Force, what he was really talking about was detecting the decay of the Higgs boson. We could not expect a former Jedi Knight to know about the Standard Model of atomic theory, so all can be forgiven for misrepresenting the true identity of the source.

RFM