Friday, February 20, 2009

Race For the Higgs (or no Higgs)


In the early 1990's, under the first President Bush, the United States planned the Superconducting Supercollider. Designed to find (or possibly not find) the legendary Higgs Boson, the project was spearheaded by Nobel Laureate Leon Lederman--see his book "The God Particle." The SSC was cancelled during the Clinton administration. The unemployed physicists took jobs in other fields, like supernova cosmology, and tried to find new energies there. In the ensuing years, with the construction of CERN, the Higgs was expected to be found by Europeans.

Tommaso Dorigo has kept us faithfully posted about progress at the CDF in Fermilab. From the AAAS meeting in nearby Chicago, we learned that they may find (or not find) the Higgs first. One week after turning on, the LHC suffered damage (picture above) that will keep it out of action until next year. A CERN physicist I talked to called this a "gas release," most people would call it an explosion. Director Pier Oddone, whom this writer was introduced to in St. Louis last May, put the odds at better than 50% of Fermilab finding the Higgs. If the mass is lower, in the 170 MeV range, Fermilab's odds go to 96%. The CERN people visting Chicago would heartily disagree, so the race is on.

There is also the possibility that the Higgs does not exist, at least at the mass range predicted. If so, the two teams will be racing for something that is forever beyond their reach. With physicists invading astronomy with their high-energy methods, it is tempting for competing groups to make premature claims. From experience with "inflatons" and "dark energy," even standard models can be wrong. Higgs or no, CDF and LHC both explore energies where no one has gone before.

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4 Comments:

Blogger Kea said...

Exciting times! But when Fermilab finds no fairy fields, there will probably be quite a few years before CERN says anything about it.

8:42 PM  
Blogger nige said...

The interesting thing about the Higgs field is that it is linked to quantum gravity by being gravitational "charge", i.e. mass. So sorting out the electroweak symmetry breaking mechanism in the Standard Model is a major step towards understanding the nature of mass and therefore the charge of quantum gravity. This is a point Dr Woit makes in his 2002 paper on electroweak symmetry, where he shows that you can potentially come up with symmetry groups that give the chiral symmetry features of the Standard Model using lie and clifford algebras. The Higgs field, like string theory, is something not observed yet prematurely celebrated and treated as orthodoxy. But it is not confirmed and is not part of the Standard Model symmetries, U(1) x SU(2) x SU(3). These symmetry groups describe the observed and known particles and symmetries of the universe, not the Higgs boson(s) and graviton. There is no evidence that U(1) x SU(2) is broken at low energy by Higgs. This symmetry is not there at low energy, but that doesn't prove that the Higgs mechanism breaks it!

In addition to providing mass to SM particles, the role of the Higgs field is to break the electromagnetic interaction U(1) away from the whole U(1) x SU(2) x SU(3) symmetry, so that only U(1) exists at low energy because its gauge boson is massless (it doesn't couple to the supposed Higgs field) unlike the other gauge bosons which acquire mass by coupling to the Higgs field boson(s).

The way a Higgs field is supposed to break electroweak symmetry is to give mass to all SU(2) weak gauge bosons at low energy, but leave them massless at high energy where you have symmetry.

This is just one specific way of breaking the U(1) x SU(2) symmetry, which has no experimental evidence to justify it, and it is not the simplest way. One simple way of doing adding gravitons and masses to the SM, as seen from my mechanistic gauge interaction perspective might be that, instead of having a Higgs field to give mass to all SU(2) gauge bosons at low energy but to none of them at at high [i.e. above electroweak unification] energy, we could have a chiral effect where one handedness of the SU(2) gauge bosons always has mass and the other is always massless.

The massless but electrically charged SU(2) gauge bosons then replace the usual U(1) electromagnetism, so you have positively charged massless bosons around protons giving rise to the positive electric field observed in the space there, and negatively charged massless bosons around electrons. (This model can casually explain the physics of electromagnetic attraction and repulsion, and makes falsifiable predictions about the strength of the electromagnetic interaction.) The massless, uncharged SU(2) gauge boson left over is the graviton, which explains why the gravitational coupling is 10^40 times weaker than electromagnetism in terms of the different way exchanged charged massless and uncharged massless gauge bosons interact with all the particles in the universe.

The one-handedness of SU(2) gauge bosons which does has mass, then gives rise the weak interaction as observed so far in experiments, explaining chiral symmetry because only one handedness of particles can experience weak interactions.

So my argument is that there the Higgs mechanism for mass is a wrong guess.

Symmetry is hidden in a different way. The gauge bosons of electromagnetism are the one massless handedness of SU(2) gauge bosons, the particles that mediate short-range weak interactions. Although SU(2) x SU(3) expresses the symmetry of this theory, it is not a unified theory because SU(3) strong interactions shouldn't have identical coupling strength to SU(2) at arbitrarily high energy: SU(2) couplings increase with energy due to seeing less vacuum polarization shielding, and this energy is at the expense of the SU(3) strong interaction which is physically powered by the energy used from SU(2) in producing polarized pair production loops of vacuum particles.

So my argument is that the symmetry of the universe is SU(2) x SU(3). Here, SU(3) is just as in the mainstream Standard Model, but SU(2) does a lot more than just weak interactions; massless versions of its 3 gauge bosons also provide electromagnetism (the 2 electrically charged massless gauge bosons) and gravity (the single electrically uncharged massless gauge boson is a spin-1 graviton).

Instead of the vacuum being filled with a Higgs field of massive bosons that mire charges, a discrete number of massive bosons interact via the electromagnetic interaction with each particle to give it mass; the origin of mass/gravitational charge as distinct from electromagnetic charge arises because the discrete number of massive bosons which interact with each fundamental particle (by analogy to a shell of electrons around a nucleus) each interact directly with gravitons. Electromagnetic charges (particle cores) do not interact directly with gravitons, only indirectly via interaction with massive bosons in the vacuum. This models all lepton and hadron masses if all the massive bosons in the vacuum have a mass equal to that of the Z_0 weak gauge boson, i.e. 91 GeV. I have to try to write up a paper on this.
My (now old) blog post which includes this topic is badly in need of being rewritten and condensed down a lot, to improve its clarity. I’m trying to follow the work of Carl and Kea with respect to neutrino mass matrices and extensions of the Koide formula to hadron masses, as well as working my way through Zee’s book, which tackles most of the questions in quantum field theory which motivate my interest (unlike several other QFT books, such as most of Weinberg).

At first glance, Ryder’s second edition QFT book seemed more accessible than Zee, but it turns out that the best explanation Ryder gives is the tensor form of Maxwell equations and how they relate to the vector calculus forms, which is neat. Zee gives path integral calculations for fundamental forces in gauge theory and for QED essentials such perturbative theory for calculating magnetic moments, which I find more motivating than the totally meaningless drivel that takes up vast amounts of math yet calculates nothing in several other QFT books (particularly those which end up declaring the beauty of string theory in the final part!).

3:18 AM  
Blogger L. Riofrio said...

Great comments nige and kea: I discuss ideas we disagree with, and wish their proponents would give us the same consideration.

A Higgs field was also supposed to cause inflation, and you know what I think of that.

4:11 AM  
Blogger nige said...

Sorry, my sentence "The gauge bosons of electromagnetism are the one massless handedness of SU(2) gauge bosons, the particles that mediate short-range weak interactions" should read:

"The gauge bosons of electromagnetism [and gravity] are the one massless handedness of SU(2) gauge bosons, the [massive handedness of SU(2) gauge bosons being the] particles that mediate short-range weak interactions."

4:46 AM  

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