The discovery of the Higgs Boson back in 2012 was another victory for the standard model. It is by far the best theory we have in describing how the fundamental particles are interacting with each other at the subatomic level as they are the building blocks of all matters we see in the world. In the summer of 2014, my dream came true when I had the opportunity to travel to Geneva, Switzerland and tour the facilities of the Large Hadron Collider at CERN where the Higgs Boson was discovered. I spent two days there to check out the upgrades of the collider and attended a few lectures about the physics behind the collider which is more or less like the kind of lectures I gave to my classes. Overall, it was a thrilling experience which I enjoyed a great deal on that trip.
CERN which stands for European Center for Nuclear Research, is the largest lab facility in the world where The Large Hadron Collider was constructed beginning in the year 2001 and completed in 2008. I joined the Quarknet Group in 2003 and got involved with learning all the physics behind the construction of the LHC as well as its goal which of course is to find the Higgs Boson in order to complete the missing piece of the standard model. In summer of 2007, we travelled to Fermi Lab in Chicago to attend a major conference and met our Quarknet leader to discuss the physics of LHC.
LHC is indeed a very sophisticated machine built about 300 ft underground which is 17 miles in circumference. The superconducting magnets ( 9600 of them all together ) are providing a very strong magnetic field inside LHC which is about 100000 times stronger than the Earth’s magnetic field and it accelerates the protons to 99.9999991% of the speed of light and when they collide, exotic particles are expected to pour out in all directions and we were aiming at detecting the Higgs Boson. The collider is made to generate nearly a billion collisions per second but out of those collisions, there might be approximately 19 to 20 are of significant as the protons are much too small and it is extremely rare for any collisions to take place. But when they do, watch out. The temperature in operating the superconducting magnets must also be very low, at 1.9 K which is actually colder than outer space of 2.7K. LHC has 4 major detectors, each about the size of a 5 story building. ATLAS ( A Toroidal Large hadron collider ApparatuS) and CMS ( Compact Muon Solenoid) are the largest detectors at LHC. I visited the sites in 2014 and they were absolutely magnificent with a complete upgrade of the magnets and the beam pipes, making them stronger and more sensitive to detecting exotic particles upon collisions. LHC is the biggest and the most complex machine ever built and today we have finally discovered the Higgs Boson which was postulated back in 1964. I suppose the half century wait was quite worth it.
Last December when I was in Hong Kong for Xmas ,the newsletter from CERN informed me that LHC might have discovered something very heavy, about 750Gev which is 6 times the mass of the Higgs Boson. The part which caught all of the attention was that both ATLAS and CMS measured the same bump of 750Gev. While there are many possible theories of what that means, the data is not as significant as we wanted it to be for claiming a discovery in particle physics. The gold standard in particle physics is 5 sigma, meaning there is less than 1 in a 3.5 million chance that it is a fluke. The significant level from ATLAS was a 1.9 sigma and a 1.2 sigma from CMS. After the machine was shut down for the winter, physicists from ATLAS and CMS went back to re-reconstruct the data using new channel to channel calibration obtained on the 2015 dataset which is crucial for energy resolution and led to a 30% improvement in mass resolution correction as well as a 10% improvement in analysis sensitivity, and as a result, the significant level from CMS has gone up from 1.2 to a 1.6 sigma while ATLAS remains at 1.9 sigma. That is merely a 1 in 96 chance it is due to a fluke, much larger than the 5 sigma level. That is like tossing a coin to get 5 heads is hard, but not impossible while tossing a coin to get 21 heads is much more significant and unbelievable. So what does that mean? We need more data to come in upon switching the machine back on in the month of April and if the bump goes away then, we had just an excitement over nothing as these bumps come and go all the time in experimental sciences. But if the bump is still there or get even bumpier, then we need to take a much closer look at the possibility of a major discovery, and if so, this could be just as big as the discovery of the Higgs Boson in 2012. Many theories are awaiting such as graviton, some other cousins of the Higgs Boson, or even supersymmetry which will definitely make Stephen Hawkins a happy man afterall. As of now, gravity has not been reconciled with quantum mechanics and detecting graviton will be a major breakthrough in particle physics. Excitement is mounting globally and we have to wait until July or the latest by August to take a look at the data because by then, we would have collected twice the amount of data compare to what we have now. Will there be more surprises coming up or just another one of those ” Oh well, the bump is gone, what a Bummer.”