There’s some excitement in the physics world today as CERN has made a tentative announcement about possible evidence for the Higgs boson. The Higgs is an elementary particle that was first proposed in the 1960s by a theorist, Peter Higgs, as a way of solving some problems in elementary particle theory. It was later incorporated, for the same reasons, into the Standard Model of particle physics, where it has remained ever since, although there has not been any direct evidence for its existence.
The announcement from CERN is that two of the experiments there, doing independent analyses, see possible evidence for the Higgs at a mass of about 125 GeV. (For comparison, the proton has a mass of about 1 GeV. The heaviest known elementary particle, the top quark, has a mass of about 172 GeV.) The statistical significance of the data, however, is not high enough to claim a discovery. It could just be a statistical fluctuation that will go away as more data are collected.
A friend who is privy to these things tells me that rumours have been swirling at CERN this fall that the Higgs was not showing up in the data. It is possible that today’s announcement is political, seizing on some tantalizing, but low significance, data in order to placate critics. Time will tell.
A generally good article from BBC News states:
Finding the Higgs would be one of the biggest scientific advances of the last 60 years.
I would argue it the other way: not finding the Higgs would be bigger news, because it would mean that the Standard Model is wrong. Finding just the Higgs predicted by the Standard Model, on the other hand, would be rather disappointing. For decades, most physicists have assumed that it, or something like it, must exist.
If CERN is indeed seeing the Higgs, then the mass estimate of about 125 GeV is potentially quite interesting. The Higgs mass is sensitive to quantum fluctuations which tend to lift it to higher — much higher — values. The most popular extension of the Standard Model, called supersymmetry, has the nice property of stabilizing the Higgs mass. However, a light Higgs such as the one hinted at in these data today actually does not need stabilization as much as a heavier Higgs would. These data, therefore, lessen the need for something like supersymmetry. A Higgs discovery, if it resulted in strong constraints on supersymmetric theories, would be a praiseworthy public service.
Incidentally, I notice that many news articles on this story are referring to the Higgs boson as “the god particle”. This name comes from a book by Leon Lederman, who actually wanted to call it “the goddamn particle”, but was prevented by his publishers. The name may be safely ignored.
All Manner of Thing 
December 14, 2011 at 11:11 am
Thanks for this. I’ve been wanting a knowledgeable and level-headed appraisal of what this development means. I get the impression that the science journalists have been disoriented by the term “god particle.”
December 14, 2011 at 11:19 am
Yes, the unfortunate term has proved irresistible to some. I saw a segment on the local news last night that consisted almost entirely of riffs on ‘god particle’: scientists were ‘the faithful’, their studies were ‘pious’, there were ‘believers’ and ‘skeptics’. What a mess.
December 14, 2011 at 8:42 pm
I wish I had the time to study the Standard Model more in depth, as well as models beyond the Standard Model, but do you know if interactions of the Higgs boson with its own field is responsible for the Higgs’ mass?
I assume that since the Higgs field is only responsible for electroweak symmetry breaking, the Higgs field is not responsible for masses of particles that lie beyond the electroweak scale, is that correct?
December 15, 2011 at 2:38 pm
Ah, Vince, you ask good questions. I’m afraid I’m a little rusty…
The mass of the Higgs is an unconstrained parameter in the Standard Model. At the electroweak symmetry breaking scale the Higgs potential transitions to a form with a non-zero vacuum expectation value (vev), thereby breaking the symmetry. This affects the fermion masses because of Yukawa interaction terms which are permitted by the symmetries of the theory and which couple to the vev of the Higgs. It affects the gauge boson masses through the Higgs mechanism. But the mass of the Higgs itself is set by the vev, which is set by the higher-scale physics that breaks the symmetry in the first place.
I believe that, as with other particles, the Higgs mass receives corrections from higher order Feynman diagrams, but such corrections do not themselves induce its mass. (One could not, for instance, compute the Higgs mass on a lattice, as one can with the proton mass.)
As to your last question, I do not think there is any reason, in principle, that the Higgs could not affect masses above the electroweak scale. If a non-zero Yukawa coupling exists between the Higgs field and a fermion, then the fermion will acquire mass when the symmetry breaks.
December 19, 2011 at 5:05 pm
And reading this, fellow readers, is when you remember that the author of this blog is a much, much nerdier and scientifically advanced life-form than you realized from his opera reviews…
December 20, 2011 at 10:41 pm
A little jargon goes a long way…
December 22, 2011 at 5:40 am
The Higgs mass (125 GeV)wass calculated in our paper ” Nondecelerative Cosmology – Background and Challenge “, published in Pacific Journal of Science and Technology 12(1), 214 – 236 (2011).
Exact value of Higgs mass is 125,39 GeV.
December 22, 2011 at 11:26 am
What I meant to say was that the Higgs mass is not computable within the Standard Model.
December 22, 2011 at 1:46 pm
Nondecelerative Model is nonstandard Model of Universe.