Higgs Boson part 2: the Search for the "God Particle"

January 11, 2012 -- Part 2


In Part 1 of this newsletter we discussed why theorists proposed the Higgs boson and what function they expect it to fulfill.


Now, how goes the experimental search?


Finding the Higgs boson was the primary justification for building CERN’s $10 billion particle accelerator, the LHC (Large Hadron Collider), near Geneva, Switzerland. The Higgs was so intensely promoted that the media and public now await the “God Particle’s” discovery almost as a Second Coming. Since the last major U.S. particle accelerator was shut down in September, the LHC is the only chance to find the Higgs. Over 5000 physicists from about 200 institutions and 40 countries are working on two detectors, ATLAS and CMS, at the LHC. They have so far combed through 400 trillion particle collisions, looking for something new. Below is a computer reconstruction of the debris from one such collision, an “event”, showing two high-energy photons (red lines) plus a myriad of other particles.




Unfortunately, Higgs bosons do not have a unique signature — they are thought to decay in many different ways, all of which can occur through numerous Higgs-less processes. The only hope is to look for a larger than expected number of certain types of events, and see if these seem to come from a new type of particle, one with a mass never seen before. All this is made far more difficult by the complexity of events at this high energy, as seen above. In December, ATLAS and CMS jointly published some tantalizing data, shown below.




The mass of a potentially new particle is plotted on the horizontal axis, and the number of events is plotted on the vertical axis. The dark jagged line shows the number of observed events, while the dotted line shows the number of events expected without Higgs.


The data aren’t definitive. The data do seem to have more events than expected at masses between 110 and 180, which could be evidence for Higgs. But, there are also excess unexplained events between 190 and 300, and more above 490. And there are far fewer than expected events between 300 and 420; it’s very difficult to explain finding fewer events than expected. I’ve seen innumerable graphs of high-energy physics data — the most convincing graphs showed data that nicely matched expectations from known processes with an additional prominent spike in a definite position. These data aren’t that convincing – at least not yet.

ATLAS and CMS will continue taking data. With increased statistical precision, we hope the Higgs question will be settled before the end of 2012.


If ATLAS and CMS don’t find the Higgs, some Higgs enthusiasts will no doubt fall back on theorists’ favorite refrain: “It’s really there, but just too heavy for current accelerators to produce.” And, even if scientists prove the Higgs does not exist, have no fear — particle masses will not disappear. Nor will theorists be at a loss for other explanations. Numerous Higgs-less theories abound, including: “technicolor”; extra dimensions with five-component gauge fields; Abbot-Farhi composite vector bosons; top quark scalar condensates; and a “braid model” compatible with loop quantum gravity. Don’t ask.


If ATLAS and CMS do find the Higgs, a whole new field of research will open: unraveling all its properties, including why it interacts so differently with each of the currently known particles. This could develop into a great discovery, and perhaps even live up to its hype.


Part 1 is available on my website.




Dr. Robert Piccioni



Author of "Everyone's Guide to Atoms, Einstein, and the Universe",
"Can Life Be Merely An Accident?"

& "A World Without Einstein"