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Higgs and then what?

  1. May 8, 2015 #1
    So, the Higgs boson might be one of the most important discoveries in terms of the standard model. I'm new to the standard model, and had a few questions related to the future of its research.

    If the Higgs is ultimately what creates gravitational fields, or at least gives things mass (and is therefore a candidate for interacting with dark matter), what particle, if any, is responsible for imparting charge and what particle is responsible for creating the strong force in protons and neutrons? Are they already discovered (low energies) or only hypothesized (maybe) ?

    If only hypothetical, what sorts of energies would they exist at? If orders of magnitude higher than the Higgs, what energy is required to create a self sustaining black hole (obviously something undesirable)? It's just always kind of important to see what direction the next paradigm shift might come from, and so I'm just wondering if this is a possibility for the next major advance in science. Please excuse the speculation in advance (something for which I've actually had a thread taken down over, so I guess keep it as scientific as possible).
     
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  3. May 8, 2015 #2

    ChrisVer

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    It's not like the Higgs creates gravitational fields. It's more like that the particles obtain their mass because they can interact with a "constant" field (Higg's vev).
    So it's not giving much insight on the dark matter either.

    I don't understand this question quiet well. I guess you are asking for a particle that gives the charge? Well, there is none. The electric charge is a leftover of the Spontaneously Broken Symmetry that occurs via the Higgs mechanism. In particular when you break the Electroweak symmetry SU(2)xU(1), there is a U(1) subgroup that remains unbroken -so the photon remains massless- and it's that of the electromagnetic force (and has the charge as the generator of the symmetry)

    For the strong force between nucleons (low energies) you have the pions. For the strong forces for the constituents of the hadrons (quarks) you have the gluons. Both pions and gluons are known to exist.

    It's impossible to create a self-sustaining black hole from particle collisions. I think that the black hole you'd create would evaporate almost instantly by Hawking Radiation. If there are no extra dimensions to dilute gravity, I guess that you'd be able to create a black hole at the energy scale where gravity can overcome in power the rest of forces - around the Planck Mass scale (10^(19) GeV).


    For what comes next, nobody knows. The Standard Model -although people tend to call it "complete" from the particle content speculation after the discovery of Higgs- for me it's not yet completed (for example we haven't found the axions, and so the strong CP-problem is still on). There are more questions to be answered within the standard model, and beyond (next searches will certainly look for physics beyond the standard model).
     
  4. May 9, 2015 #3

    mfb

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    The Higgs particle does not give mass to anything. It is the Higgs field. The particle is an excitation of this field without much relevance on its own (it just allows us to study the field).

    It is important to highlight that those are not in any way "equivalent" to the Higgs.
    The quarks have their color charge, there is no special field or particle responsible for it. The gluons couple to this charge, in the same way the photons couples to electric charges.


    The smallest black hole is probably around the Planck mass - it could be lower, we don't know. Those would evaporate quickly, however. To make it large enough to capture matter faster than it radiates away energy, it would need a mass of at least millions of tons or ~1036 GeV (probably even more).
     
  5. May 19, 2015 #4
    Ok. That's what I thought as far as the black hole thing. I had heard that there was some initial concern over the LHC initially by some fringe scientists, and knew it was ruled out, but wanted some numbers, so that's very helpful.

    As for the standard model, apparently I don't understand it very well despite having read a book on the subject. I guess that book I read didn't get into the nitty gritty of it. I knew quarks had something to do with strong force (or remember having read about that vaguely). And, I remember reading something that vaguely went over how photons are the massless particles of the electromagnetic force, the force carriers I think they have been called. Again, it sounds like this question went more in depth than I thought (as many of my questions do), and require a bit further reading before being able to grasp where the Higgs actually fits in the standard model.
     
  6. May 27, 2015 #5
    I have been mystified by what exactly the Higgs field is, because reading some descriptions of it and listening to youtube videos, posted by people who seem to know what they're talking about, I heard contradictory things. Some say the Higgs field is composed of Higgs particles, others that Higgs particles are disturbances in the Higgs field and some left me with the strong impression that the Higgs field is not composed of Higgs particles.

    This is my guess at the truth; perhaps one of the experts here can correct it: The Higgs field is composed of spread-out, maybe infinitely spread-out, Higgs particles. Therefore, there are no excitations of the Higgs field in the vacuum; the Higgs field is the vacuum field. However, Higgs particles appear at times from the collision of a proton with an antiproton if energy is high enough and probably by other means as well. My interpretation is that this "new" Higgs particle is like other massive particles and acquires its mass from the Higgs field, but it decays extremely rapidly, I seem to remember in 10e-22 seconds. Before it decays, it is an excitation of the Higgs field rather than a spread-out Higgs particle. If this is correct, though, I don't understand why interaction with the Higgs field doesn't produce more excitations of the Higgs field, that is, more Higgs particles that are not spread-out much.
     
  7. May 27, 2015 #6

    mfb

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    It is not.
    That is a better description.
    Like proton-proton collisions at the LHC.

    The Higgs particle gains some mass from the Higgs field, but it also has a mass on its own. This is possible as it has spin 0.
    The excitations need a lot of energy to get created, which is not available outside of very high-energetic collisions like in the LHC.
     
  8. May 27, 2015 #7
    The Higgs was never the real story. It only sounds really cool. Try explaining the mass of the proton or neutron just with the Higgs. It doesn't work. Not even close.
     
  9. May 28, 2015 #8

    ChrisVer

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    A proton is not an elementary particle in the Standard Model...More like it's a composite bound state... It can be described by Effective Field Theories maybe (I'm not sure about the term) low-energy limits of the Standard Model with Lambda-QCD the characteristic upper scale.
    Well the Higgs boson doesn't give the mass to particles...It's the Higgs field that does, which is only connected to the Higgs boson through the Higgs Mechanism for the ElectroWeak Symmetry Breaking...
     
  10. May 29, 2015 #9

    vanhees71

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    The problem is that the Standard Model is a QUANTUM field theory, and that's hard to explain adequately in everyday-language without the concise possibilities the mathematical formalism.

    As the name says, everything starts with a field theory. Fields are physical entities spread in space. The only elementary fields we know from our (classical) everyday experience are the electromagnetic field, which mainfests itself as "light" to our senses, and gravity which we feel as "weight". Gravity is very special, because it is described by a classical field theory only, which reinterprets it as the geometry of spacetime (Einstein's General Theory of Relativity). On a quantum level gravity is not yet understood. Fortunately for particle physics it's not important at all, and we have the very successful "Standard Model of Elementary Particle Physics" (SM).

    The SM uses mathematical principles generalizing the ones underlying electrodynamics. In the standard model we have the electromagnetic and weak forces together in a theory called "quantum flavor dynamics" and the strong force in a theory called "Quantum Chromodynamics". They all describe particles as well as interactions in terms of fields. These fields are, however, not classical fields but quantum fields. This formalism admits an interpretation of these fields as a description of particles.

    Now the mathematical structure of the ST doesn't admit to give the elementary particles described by it in terms of quantized fields a mass by simply adding the appropriate mass terms into the theory, because this destroys the mathematical structure the whole edifice is built on (the socalled local gauge symmetries). As was figured out by Anderson, Higgs, Guraldnik, Kibble, Englert, and Brout in the early 1960ies there's a way out of this dilemma: You introduce another field to the theory which has a non-zero vacuum expectation value. With the appropriate couplings between this Higgs field the other particles (quarks, leptons and some of the gauge bosons, the socalled W and Z bosons) get a mass without violating gauge invariance, and everything is fine. Now Higgs concluded that with the introduction of the field, now named after him the Higgs field, there's also one more (or, with more complicated realizations of this Higgs mechanism even more than one, although as far as we know from the observations at the LHC it seems as if nature has realized the most simple minimal Higgs sector) scalar particle, which is consequently named the "Higgs boson". On July 4, 2012 ATLAS and CMS, two large collaborations working at the LHC, announced the discovery of the Higgs boson, and Higgs and Englert got the Nobel prize in the next year. Now, the more data from the LHC are analyzed, the more the discovery gets strengthened. The seen particle has precisely the properties predicted by the standard model.

    Another question is, how much of the mass of the matter surrounding us is in fact due to the Higgs mechanism, and the answer is it's only a tiny fraction of about 2%. All the rest of the mass of theprotons and neutrons making up the atomic nuclei, which together with the electrons make atoms and molecules which are the constituents of the matter around us, is dynamically generated due to the strong interaction, binding together the hadrons (i.e., in this case the protons and neutrons) out of quarks and antiquarks.
     
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