Talk:Higgs mechanism

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1 applied to photons
2 Mass generation
3 References
4 citations
5 No title

[edit] applied to photons

Why does the Higgs mechanism not give mass to photons? --63.26.56.28 17:43, 5 May 2006 (UTC)

Actually under certain circumstances it does. (At least an absolutely similar mechanism can explain the meißner-effect in superconductors.) But in the standard model (so not in a solid but in the vacuum) you can just measure masses for the weak gauge bosons. Perhaps, there is a good article in en:wikipedia on the electroweak theory. This ought to be the right place to turn to. :) -- 84.61.164.214 20:56, 30 June 2006 (UTC)

A simple question: what is the $v 2$ in this equation?

$V(x,y,z) = \left(|H(x,y,z)|^2 - v^2\right)^2$

[edit] Mass generation

I think the sentence "It also gives mass to all the other elementary particles in the standard model" is a bit misleading. Someone could think that fermions get their mass from this mechanism exclusively. —Preceding unsigned comment added by 134.2.78.97 (talk) 11:51, 29 October 2007 (UTC) Saying that the Higgs particle or Higgs mechanism "gives mass" to other particles is completely incomprehensible to anyone except a theoretical physicist. Some type of explanation for students and professors in other fields would be greatly appreciated. --Bob Goldstein MIT Physics 1970. —Preceding unsigned comment added by Bob124c41 (talk • contribs) 02:52, 11 February 2008 (UTC)

By this statement people mean that all the particles in the standard model are necessarily massless--- they cannot get a mass because their different helicity states do not have the same charges.

A massive particle with spin 1/2 can be thought of as two different helicity states (not counting antiparticles) which flip into each other constantly. But in the standard model, the different helicities of particles have different charges. One helicity of the electron is part of an SU(2) doublet with one U(1) charge and the other is a singlet with a different value of the U(1) charge. So you can't have a massive electron because if you flip helicity you violate charge conservation. For the same reason, you can't have massive quarks.

But the weak SU(2) and U(1) are Higgsed, so the electron helicity can flip by absorbing a particle from the condensate to make up the missing charge. This effect can be written down simply by just replacing the condensate with its classical value, and then the electron in this classical field is massive.

The neutrino cannot get a mass because it cannot flip helicity by absorbing one Higgs. In order for the neutrino to get a mass it must flip helicity, and turn into an anti-neutrino, and the easiest way for this to happen is for the neutrino to absorb two Higgs bosons at once. This effect is suppressed naturally by the improbability of two nearly simultaneous Higgs absorptions, but it can happen if there are intermediate states available for a neutrino + 1 higgs.

This is important for several reasons:

it tells you that all the particle states with definite helicity have to have different charges, so that they cannot have a mass if not for the Higgs. The idea is that if they could have a mass, you would expect it to be of order 1 unit, where the unit is the Planck mass which is enormous. We would never see particles that heavy.
it tells you that the mechanism of SU(2)/U(1) breaking also sets the scale of particle masses--- so that all particles (electrons/quarks) have the same mass up to factors of order unity.
it tells you that the neutrinos must stay massless, except for interactions which are not renormlizable. This puts severe constraints on extensions to the standard model.
it explains the CKM matrix.

This is the standard model. But it is only peripherally related to the Higgs mechanism itself, so it might not belong on this page.Likebox (talk) 00:50, 12 February 2008 (UTC)

[edit] References

[edit] citations

where are they? 69.112.164.135 (talk) 18:46, 26 April 2008 (UTC)

eh? --Michael C. Price ^talk 09:42, 27 April 2008 (UTC)

[edit] No title

The way in which history is written is a strange one, especially when it comes to science... The "official" story that you can read everywhere (including here) is that the Higgs mechanism was (as the name suggests) 'originally proposed' by Peter Higgs. Slightly better-informed sources sometimes mention that the mechanism was "independently discovered by Brout and Englert as well as Hagen, Guralnik, and Kibble". In reality, and as Higgs himself has several times pointed out: "they were clearly ahead of me",see e.g. http://www.cpa.ed.ac.uk/bulletinarchive/1996-1997/11/news/26.html and http://physicsworld.com/cws/article/print/19750

The chronological truth is indeed that the so-called Higgs mechanism was 'originally proposed' by Peter Higgs ^[1], François Englert and Robert Brout ^[2], and by G. S. Guralnik, C. R. Hagen, and T. W. B. Kibble ^[3].

Guralnik at Brown Univ. recalls his part in Higgs history here: http://chep.het.brown.edu/stlouis-v4.pdf I always wonder why the anglo-saxon scientific world is always so imperialistic, not to say revisionistic. Either it's because anglosaxons just can't remember any non-english sounding name, or they really want people to believe that every single thing in modern science has been invented either by an American or a British.

I just left a note on the talk page of Higgs on the German wikipedia bringing up this issue. Hopefully this can be straightened out fairly and civilly.-Richard L. Peterson130.86.14.12 (talk) 19:37, 17 March 2008 (UTC)Rich (talk) 19:38, 17 March 2008 (UTC)

It's perfect just the way it's written now in the main article: Brout and Englert were first, Higgs a couple of months later, Kibble & co a few months later again, so they should indeed be stated in this order. The mechanism is usually referred to as the Higgs mechanism (probably mainly because Higgs was the one who made most publicity for it and maybe also because his derivation was easier to understand than Brout and Englert's) - so the main title shouldn't be changed, although it might be nice to have separate entries created for Brout-Englert-Higgs mechanism etc and link these to this entry. (Imtg5102 (talk) 15:11, 18 April 2008 (UTC))

I think the reason for the name is that 'tHooft read Higgs, and 'tHooft is Dutch so it's not an anglo-saxon conspiracy. I don't think that 'tHooft and Veltman really cared very much about proper attribution--- they called some of their original relations "Bell Trieman identities" as a joke, to see if Bell and Trieman would get credit for them. I think Slavnov and Taylor got the credit in the end.Likebox (talk) 20:45, 14 May 2008 (UTC)

Ironically, 't Hooft is now probably one of the people outside of Belgium (though IMHO correctly) calling it the "Brout-Englert-Higgs mechanism", see http://arxiv.org/abs/0708.3184. In any case, interesting anecdote, though I don't know if it's correct, Higgs seems to give another story for why only his name got attached to it, see his article "prehistory of the higgs boson" (end of par.3). Maybe we should delete the reference to 't Hooft coining the name, ar on the contrary add a reference? (I guess we could also just stop discussing this, wait if anything shows up at the LHC, see who gets the Nobel prize and then start arguing again...) Imtg5102 (talk) 15:56, 15 May 2008 (UTC)

I think that is right – everyone will just have to wait. All six will not get the Nobel Prize as only three can win it. With six people (plus the experimentalists) claiming (and deserving) credit, the Nobel Prize will have to wait until there are only three alive or the academy can expect quite a controversy on its hands.