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Is Higgs just a force?

  1. Aug 20, 2008 #1
    Hello

    I am trying to understand the function of the Higgs bosun which appears to lend mass to other particles. But what if it has no mass and is purely a force? Could the Higgs force be assimulated by another particle but at the same time it also imparts a reactional force - gravity.

    If so it would seem to produce a 'mass' effect and it would be difficult to produce in the LHC.

    Thanks - 246Ohms
     
  2. jcsd
  3. Aug 20, 2008 #2

    Vanadium 50

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    I don't know what this means, but the Higgs mass must be non-zero. Experimentally, we don't see a long-range force that behaves as the Higgs does, and the theoretical framework that makes a Higgs a Higgs has the relationship [tex]m/\lambda = 246~{\rm GeV}[/tex], where [tex]\lambda[/tex] is the Higgs self-coupling, which is non-zero.
     
  4. Aug 20, 2008 #3

    malawi_glenn

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    We have many old thread about this topic.
     
  5. Aug 20, 2008 #4

    blechman

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    If there is a higgs boson, it must have a mass. Even if you ignore the experimental evidence that we never saw it (maybe it decays in some super-bizarre way, which is why we didn't see it) there is still a lower bound on its mass coming from the stability of the vacuum. This bound is very weak (about 4 GeV), but it is definitely not zero.

    Depending on how seriously you want to take the data, the higgs mass has experimentally been shown to be larger than 114 GeV (in the standard scenario) or more loosely 80-something GeV in more open-ended searches. Precision EW measurements also allow for the mass to be no bigger than around 250 GeV, and if you ignore that, other quantum effects enforce a stronger upper bound at around 2 TeV (to prevent the higgs from becoming strongly coupled, which would forbid it from doing its job in giving mass to the standard model particles).
     
  6. Aug 21, 2008 #5
    If Higgs is predicted by the SM and we argue its existance based on the model then it must exist as a mass. Some however are not so sure that the SM or even SS predict the Higgs field as a new one and others even propose it may be a quark or lepton field and if so it would be massless and as blechman says above the experimental evidence so far has not seen it.

    My question is could Higgs be just a force that induces mass but also has a reactionary force - for instance gravity ie is the Higgs force connected to gravity. From a circular analysis gravity acts on mass and mass is supplied by the Higgs .... So whats the connection? Its an outside the box question.

    Thanks 246ohms
     
  7. Aug 21, 2008 #6

    Vanadium 50

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    I still don't understand what you are talking about. "we argue its existance based on the model then it must exist as a mass" doesn't make sense, nor does "My question is could Higgs be just a force that induces mass but also has a reactionary force - for instance gravity ie is the Higgs force connected to gravity." Perhaps if you were to use standard terminology more people would understand what you write.

    Nevertheless,

    is clear. And it's not the case.

    Do you understand the Higgs mechanism in the Standard Model? If so, it would help to pose your question in standard terminology. If not, I would suggest that the first step before declaring that it's wrong is to understand what it actually says.
     
  8. Aug 21, 2008 #7
    If all particles with mass are supposed to derive all of their mass from interactions with Higgs-particles, the logical conclusion would be that Higgs-particles have mass if and only if they interact with each other.

    However, charged particles like the electron carry mass in their electromagnetic field. Some of their mass must therefore be due to something else than interactions with Higgs-particles. Unless, of course, their charge is also caused by interactions with Higgs-particles.
     
  9. Aug 21, 2008 #8

    malawi_glenn

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    If we are talking about a 'higgs particle' and 'higgs field' and 'higgs mechanism' that is not included in the electroweak SM, then it is pointless to even calle it Higgs, Just as Vanadium 50 is trying to tell you: Either relate the question and language to the higgs of the SM, or study it, or ask about alternative models for including mass to particles.

    So, 246ohms: In the electroweak SM - Higgs mechanism is not a force, and is not there to explain the force of gravity either. The thing that higgs field does is to give mass to the quarks and leptons.

    Almanzo: You reasoning about the electron mass is not based on based on physics but of some 'intuitive' feeling, not ok, back to school.
     
  10. Aug 21, 2008 #9
    Actually, it is based on The Feynman Lectures on Physics, part II, chapter 28.
     
  11. Aug 21, 2008 #10

    malawi_glenn

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    There is nothing about Higgs there..
    Chapter 28.3 is about classical electrodynamics...which is not relevant so much in quantum field theories....
     
  12. Aug 21, 2008 #11

    Vanadium 50

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    I don't particularly care for that section in Feynman, largely because Feynman doesn't make it clear that this is generally regarded as a dead end. If you try and explain the electron's mass as purely electromagnetic in origin, you eventually get contradictions like [tex]m_e = \frac{4}{3} m_e[/tex]. This was known around the turn of the (last) century. But what really did this in was the discovery of the muon, a particle just like the electron but 200 times heavier.

    Quantum mechanically, the situation is simpler. These effects are called "radiative corrections", and they get absorbed into the Higgs Yukawa coupling. So it's already included in the Higgs contribution.

    Again, I think it's a very good idea that before declaring a theory to be wrong or incomplete that one spends some time understanding what the theory actually says.
     
  13. Aug 29, 2008 #12
    Sorry to have taken this long to reply; but I usually have time to visit once or twice a week only.

    What Feynman seems to say, is this. Some (but definitely not all) of the electron's mass must be due to the electromagnetic field (and actually reside there, and not in the electron's "body"). Some other part of its mass must be due to "Poincaré stresses", that is: to whatever is preventing the electron from flying apart. And some of the mass may be due to something else.

    What the Higgs theory seems to say (as presented by some post in this thread) is that all of the mass of every particle (including the electron) is due to interactions with Higgs-particles.

    I do not pretend to know anything else about the Higgs theroy, but I am struck by an apparent contradiction. If some of the electron's mass is due to its having a charge, and all of its mass is due to interactions with Higgs particles, something has to give. Perhaps the Higgs particles are also responsible for the electron's charge? Then it could both be true. But there should be some explanation on how to reconcile the Higgs idea with, for
    example, the formula for the electromagnetic energy density on top of page 146 in the Cambridge Handbook of Physical Formulas. It was published in 2000, so I don't think that it is obsolete.

    And I think that this would be, generally, the explanation which 246ohms requested when he started this thread.
     
  14. Aug 29, 2008 #13

    Vanadium 50

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    I don't think Feynman would agree with the "must". As I alluded to before, if you work out how much of the mass is carried in the self-interaction with the electric field, it works out to 133% of the mass. That's (one reason) why this line of thinking is essentially dead. Another is that this is a purely classical theory attempting to describe a quantum mechanical object.

    It does not say this. The only particles that the Higgs must give mass to are the W and Z bosons. Fermions can have a Dirac mass that has nothing to do with the Higgs. Alternatively, a completely different Higgs gives mass to the fermions.


    Again, I think it's a very good idea that before declaring a theory to be wrong or incomplete that one spends some time understanding what the theory actually says.
     
  15. Aug 29, 2008 #14
    I did not declare anything of the sort. I was asking for an explanation.
     
  16. Aug 29, 2008 #15

    blechman

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    I agree with this, but let me also expand on it. It is true that there is "self-energy" of the electron coming from its interactions with the electromagnetic field. Classically this doesn't work, as Vanadium_50 says. In QED, this effect is real. There is an (infinite) contribution to the electron's mass. To a QFT expert: an infinite mass correction implies that the electron mas RUNS, that is, the value of the mass you measure for the electron depends on the energy at which you measure it. I do not want to hijack the thread with a talk about renormalization group methods, but if you're interested, read up on that as well.

    HOWEVER, even in this case, the Higgs field has to play a role, since an electron mass is not allowed by the symmetries of the SM without a Higgs (see below). So you see, even with these EM contributions, the Higgs is involved. To see how this works explicitly would require some knowledge of QFT, but if you actually compute the QED corrections and be careful, you find the Higgs is part of the picture, at least in the current version of the SM. For the experts: the loop requires a mass insertion to renormalize the mass.

    Another way to see this (although a little more technical): In the classical theory, the EM mass of the electron is "linearly divergent". In the quantum theory, it is "LOG divergent". Dimensional analysis then says that there must be a mass scale for the electron to get a correction, and the only mass scale around is the Higgs vev. This emphasizes that there is a VITAL difference between the classical calculation and the QFT calculation (the latter being the correct one!). :wink:


    Well, it is certainly true that this COULD be the case. However, the "Standard Model" has the Higgs doing double-duty. The point being that you cannot write a Dirac mass for any of the fermions without somehow breaking the gauge symmetry. Minimally, the Higgs is what does that. Extensions of the SM are interesting, but we might not want to go that way here.
     
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