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Electroweak Symmetry Breaking

  1. Nov 20, 2011 #1
    What law of nature says that electroweak symmetry must be broken? Is it possible that in other parallel Superstrings (or others) universes.. electroweak symmetry were not broken and even after temperature of the Big Bang decreased to what is like ours, electroweak symmetry still existed in that universe? If so. The difference between our universe and it is due to our luck that we have stuff like Higgs or other alternatives that break electroweak symmetry? In other words. Is it a requirement of law of universes that electroweak symmetry must always be broken?

    Also do you consider spacetime as a symmetry? Here our spacetime symmetry are not broken, or is it? If not. Then maybe we live in a universe that spacetime symmetry were not broken compared to other universes. What would be it like in a universe where the spacetime symmetry were broken (just wanted to under how to look at electroweak symmetry breaking/non-breaking from all angels)?
     
  2. jcsd
  3. Nov 20, 2011 #2
    Quantum field theory dictates that the existence of massive vector bosons (W and Z particles), discovered in the 1980s in particle accelerators, is only possible with electroweak symmetry breaking.
     
  4. Nov 23, 2011 #3

    tom.stoer

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    The lagrangian of the standard model.

    Are you asking whether it's possible to write down a different lagrangian with different symmetry properties? Yes it's possible. You don't need superstrings to do that. Write down the SM lagrangian w/o Higgs.

    Afaik it's not possible to strictly derive the SM from any string theory - neither w/ nor w/o Higgs.

    In our universe in which the SM holds - yes; in other possible universes - no (if you like such speculative ideas ...)

    What do you mean by spacetime symmetry? Diffeomorphism and (locaL) Lorentz invariance in GR? As far as we know these symmetries are not broken.

    There are different ways to 'break' these symmetries ...
     
  5. Nov 23, 2011 #4
    One can send electromagnetic signal at lightspeed in spacetime.. so can electrons or protons below lightspeed by sending them for example in particle accelerator or cathode tubes. How about the Higgs field. Can't one use it to send higgs signal from say USA to Europe at or below lightspeed? Why not?

    In model building in Unified Theories. When one invent a new field (like Higgs field). Must it always follow the law of General Relativity.. meaning no rest frame? But GR is not the final theory because of its incompatibility with QM.

    In local lorentz invariance violation experiment. For example. If they found out planck scale violate lorentz invariance.. meaning there is a nonzero vector field... so I guess one can use this to establish absolute space/time even when apart say between earth and pluto by treating the planck scale as the preferred frame? If not. What arguments totally refute this?

    Thanks.
     
  6. Nov 23, 2011 #5

    Bill_K

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    The Higgs field is a scalar, and takes on the same value at every point in every rest frame. The Higgs boson is a scalar particle and extremely short-lived, 10-25 or 10-26 sec.
    No, that's Special Relativity.
    The Planck scale is simply a combination of physical constants, G, c and ħ. They are all scalars, the same in all rest frames, and there is absolutely no reason to think otherwise.
     
  7. Nov 23, 2011 #6
    But Planck scale may not be that "simply". It is the heart and meat of search for Final Theory. Do you believe time doesn't exist there?

    http://discovermagazine.com/2007/jun/in-no-time/article_view?b_start:int=1&-C=

    Or do you believe Space doesn't exist in Planck Scale?

    http://arxiv.org/abs/0909.1861

    Or do you believe Planck contains 11 Spacetime Dimensions as in Superstring Theory?

    What do you think is in planck scale where the equations of quantum mechanics and general relativity break down?
     
  8. Nov 24, 2011 #7

    tom.stoer

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    That's a naive statement.

    There are indications that gravity can be quantized non-perturbatively but more or less in a standard way, and that this theory (asymptotic safety) is still well-defined near Planck scale. What breaks down is perturbative quantization of gravity, but we know other examples where this approximation is inadequate (bound states in QCD).

    We do not know (yet) how to formulate a theory quantum gravity.
     
  9. Nov 24, 2011 #8
    So scalar fields like Higgs and Inflaton field can't be used to "move" in spacetime because they are not vectorial. Beside the following vectorial field:

    1. Electromagnetic wave
    2. Gravitational wave
    3. Weak force wave
    4. Strong force wave

    Is there any law of physics that says that no other vectorial field can exist?

    If not. And if there were another vectorial field not yet discovered in physics. Does it have to be a force like the above fundamental force? It appears all fundamental force are vectorial force. Why can't fundamental force be scalar?
     
  10. Nov 25, 2011 #9

    tom.stoer

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    A scalar field can be used to 'move through spacetime'. The pion field (it's not an elementary particle, but that doesn't matter) is a scalar field. The pion is instable, but has a rather long lifetime such that e.g. pion beams can be generated.

    There is no (known) law in physics which determines the elementary fields in the standard model. There is no physical law which forbids adding new forces - the only thing is that we do not observe them. That means that we do not understand WHY we onserve exactly the particles and forces which are described in the SM. We can describe them - fine - but we can't explain their origin.
     
  11. Nov 25, 2011 #10
    Earlier in the thread when I asked you "How about the Higgs field. Can't one use it to send higgs signal from say USA to Europe at or below lightspeed? Why not?"

    You answered: "The Higgs field is a scalar, and takes on the same value at every point in every rest frame. The Higgs boson is a scalar particle and extremely short-lived, 10-25 or 10-26 sec."

    I thought you meant scalar couldn't be used to 'move through spacetime'. But in this message, you said it can. So the higgs boson can be made to move a short distance in the LHC detector, isn't it. But at relativistic speed, it can last thousands of times longer.. so can't one send higgs boson at a distance of say 1 mile?
     
  12. Nov 25, 2011 #11

    tom.stoer

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    The fact that the Higgs field is a scalar field has nothing to do with the problem of sending messages through space; it only says something regarding it's transformation properties w.r.t. Lorentz transformations. The Higgs particle decays extremly fast, so it's difficult to send signals over macroscopic distances.

    It can. I understand you confusion about the grammar in "... takes on the same value at every point in every rest frame". This does not mean that the field is constant, but that the value of the field at a certain point in space looks the same for all observers (all reference frames). Of course this value can be different at different points in space, and the field can "propagate".

    Yes

    It already has relativistic speed a LHC. It has a mass (if it exists ;-) of approx. 100 GeV/c² but is created in collisions of some TeV it's speed could very well be in the range of ~ 100 GeV to ~ TeV, therefore it's already at relativistic speed. But in order to send it over 1 mile its speed and therefore its kinetic energy have to be VERY large (this is a nice exercise in special relativity and time dilation).
     
  13. Nov 25, 2011 #12
    Do you know of other scalar field that can also propagate in space? How does it differ to vectorial field as far as movement is concerned? None? But you said scalar and vector differs only with respect to lorentz transformation.. how? something got to do with polarization or something?
     
  14. Nov 25, 2011 #13

    tom.stoer

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    Pions (I do not now any example of a physical field that does NOT propagate).

    Different field equations (compare Maxwell equations and Klein-Gordon equation); but for free fields e.g. E² = p² + m² always holds.

    Have a look at http://en.wikipedia.org/wiki/Lorent...z_transformation_of_the_electromagnetic_field

    Example: suppose you are an observer at rest looking at a point like charge at rest. What you see is the radially symmetric, electric Coulomb field; now suppose you move with a certain speed w.r.t. to the same charge.; of course you will still see a charge, but due to Lorentz contraction the field gets deformed; in addition the charge is also moving w.r.t. you - but moving charges create magnetic fields, so you in addition you will see a magnetic field, which is not there in the rest frame of the charge.
     
  15. Nov 25, 2011 #14
    We have narrowed the window for the allowed values of the Higgs boson mass to be 114-141 GeV. Have they taken the Inflaton field and dark energy into consideration? Isn't it that new forces and fields can affect the final masses of the Higgs boson? If not. What other particles or parameters that can be influenced if there are more particles, fields and forces not yet discovered by present physics? We may not be able to detect them.. but if they can affect the masses of higgs or other particles.. then it's one way to detect them indirectly.
     
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