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B No new fundamental particles at CERN until today

  1. Aug 26, 2017 #1
    I remember reading in some book, that the most important experiments are those that produce negative results: the Michelson-Morley experiment for example.

    The standard model is complete after the Higgs boson.
    I believe that if no new particle appears in CERN, it would be one of the greatest revolutions in physics.
    I seem to have read also, that Michelson died still believing in the Ether.

    Experimental data today: no new fundamental particles at CERN
    I hope that thinking were not sin.
     
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  3. Aug 26, 2017 #2

    mfb

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    The LHC experiments found a new particle just five years ago. "Scientists found no new particle since the last particle was found" is tautological.

    The most important experiments are experiments contradicting the expectations. Michelson-Morley was not important because it was a null result, it was important because the expectation was different from the observed null result.
    How?
    We know the Standard Model is incomplete, we have several ideas how to modify it, but without experimental hints which approach is good theorists are left in the dark.
     
  4. Aug 26, 2017 #3

    I like Serena

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    Heh. By the end of the 19th century physicists believed they had everything down, and physics would become more of an applied science.
    We had Newton's laws for gravity, Maxwell's laws for electromagnetism, and a periodic system of atoms - the building stones of the universe.
    What else could there be on a fundamental level?
    Then it turned out that it was not so simple...
    For instance Michelson and Morley showed up with their annoying discrepancy.
    And a few loose ends turned into the theory of relativity, quantum physics, the standard model, and so on.
    People today may die believing in the standard model similar to how Michelson presumably died believing in the ether.
    Ah well, all I'm saying is, let's not assume that we're anywhere close to knowing everything.
    After all, as far as we know most of the matter in the universe doesn't even properly follow the rules we came up with (95.1% of the universe is dark matter-energy). ;)
     
    Last edited: Aug 27, 2017
  5. Aug 26, 2017 #4

    mfb

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    We know the SM is incomplete and just an approximation. The situation is completely different to 1900.
     
  6. Aug 26, 2017 #5

    ChrisVer

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    what's a negative result of an experiment? I guess you reffer to new physics searches; in that case a 'negative' result is the verification of the null hypothesis (no new signal)?? How is that more important?

    If no new particle is discovered by CERN then we will :
    1) need a larger machine/project
    2) until we have it resort in other experiments.
    That's because we know that the Standard Model is incomplete (noone questions that I think). The Standard Model could potentially work up to around the Planck Mass energies; the question is does it so? or is there something between our reach and those energies?
     
  7. Aug 27, 2017 #6
    Ok. I thank you for the answers, the question has been answered so if the moderator wishes he can close the thread.
    Really, I do not want to be more conflictive: my ideas are not the ones that dominate today's physics.

    I know that this will marginalize me in the academic world, but they have told me that when new ideas are born, first they are taken for crazy, then they are insulted, and finally accepted.
    Obviously I'm not a fan of my ideas. If, with them, I am not able to explain the experimental data, then I will be forced to change them.

    Ok, thaks for your appreciable answers, I don't like to be conflictive. I greatly respect the opinions of others, because I am aware that I may be wrong.
     
  8. Aug 27, 2017 #7

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    No worries alejandromeira, I like that you've made me think about it.
    And now that I'm thinking about it, I'm curious.

    Once upon a time we found that we could create bigger and bigger atoms.
    But the bigger they were, the more unstable they got.
    And every now and then a new element is still found (typically synthesized).
    I've just found that apparently Oganesson is the highest yet (Z=118, 2002-2016).
    And it has some unusual properties (which makes me think of the Higgs boson).
    It's a 'noble gas', but it is not noble but reactive, and is predicted to be solid due to 'relativistic effects'.
    And it completes the last row that the periodic system currently has, although another row is predicted.

    Can it be that discovering these bigger and bigger fundamental particles and generations is similar?
    That we're actually looking at what can be built from smaller particles yet?
    I'm guessing that there must be theories about this already.
     
    Last edited: Aug 27, 2017
  9. Aug 27, 2017 #8

    mfb

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    There is good experimental evidence that the known elementary particles are indeed elementary.
    • If there is a substructure, you expect to see it the latest when you reach the energy of the composite object. You see the nuclear substructure with a few MeV of energy compared to several GeV of nucleus masses, and you see the substructure of a proton with less than a GeV, the approximate proton mass. We don't see any signs of substructure even at thousands of times the particle masses.
    • With a substructure, you expect excitations, again below the rest energy. Atoms have them, nuclei have them, no known elementary particle has them, not even at thousands of times the particle masses.
    • The g-factor can be accurately calculated for electrons and muons if they are elementary particles. If they are composite particles, it could be anything. The experimental values agree within 1 part in a trillion and 1 part in a billion, respectively. It would be extremely odd if this would be by accident.
    The LHC experiments look for hints of composite particles, but without much hope. Constituents would need extremely odd properties. They would have to be so heavy that we couldn't produce them yet (hundreds of GeV at least), but then combine with a negative binding energy that nearly matches their mass to give a combined mass in the MeV range for the lightest generation.
    Survivor bias. The vast majority of the ideas never makes it. It is important to have ideas, but expecting that every idea must have some value is not a good approach. If an idea doesn't turn out to be useful, drop it.
     
  10. Aug 28, 2017 #9
    Newton law for gravity is incompatible with Maxwell's EM laws: first uses Galilean space-time, second uses Minkowski space-time. So even then it was clear that then-current state of theory can't be final.
     
  11. Aug 28, 2017 #10
    This is not that odd, we already have this situation with hadrons. Free quarks have large, most likely "infinite" (divergent) masses. They combine (with a negative binding energy) to form protons et al.
     
  12. Aug 28, 2017 #11

    mfb

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    Maxwell's laws could have been valid in a preferred reference frame only. Michelson and Morley wanted to find this reference frame.
    You can probe the substructure of hadrons with 1 GeV electrons, and you get excitations below twice the hadron mass.
    There is no mass of free quarks, all reasonable quark mass definitions give the light quarks masses well below the proton mass.
     
  13. Aug 28, 2017 #12
    I know. My reply was not about that. My reply was that we already have one type of composite particles where binding energy is comparable or larger than the total energy of the bound state. Ergo, having the same situation but on a much, much, much smaller scales would not be a first.
     
  14. Aug 28, 2017 #13

    mfb

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    It is comparable, that is the point. It is not 1000 times larger. In addition, QCD binding energy is positive, not negative as we would need to to have composite "elementary" particles.
     
  15. Aug 28, 2017 #14
    It depends on how you define "quark mass". As you pointed out, "free quark mass" is ill-defined, thus people usually use "quark masses" which are markedly different from mass definitions of any other particles.

    I prefer a definition which makes binding energy of any bound system negative.
     
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