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What if quarks are real

  1. May 11, 2008 #1
    We have seen nuclear power when atoms split. Could it be ..the day we split the proton is the day we end our own world? I just hope E=mc^2 holds. :rofl:
     
  2. jcsd
  3. May 11, 2008 #2
    We have split the proton.
     
  4. May 11, 2008 #3

    malty

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    Well AFAIK we haven't directly observed them (and it may not be possible) but we definitely have indirectly observed them.
     
  5. May 11, 2008 #4
    :eek:I'm missing something.
     
  6. May 12, 2008 #5

    malawi_glenn

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    http://physics.nmt.edu/~raymond/classes/ph13xbook/node194.html

    When high enough momenta is transfered from the electron to one of the quarks in the proton, it breaks up into many other particles.

    It was done in the 1960's and 70's

    http://en.wikipedia.org/wiki/Deep_inelastic_scattering

    But the nucleons are different objects than the the nucleis, so I don't think you can build bombs and "nucleon-powerplants". You can not use an arbitrary nuclei for making bombs or powerplants, they must fulfill certain needs. So don't panic ;)
     
  7. May 12, 2008 #6
    This is MADNESS! lol thx for the info

    The articles say that when an electron hit the proton, alot of stuffs come out. We have to make up a model and interpretation. This world is forever in mystery.
     
  8. May 12, 2008 #7
    Could be everything was already there, and the collision just lit up the area so we could see it. I love how everyone thinks space is empty.
     
  9. May 12, 2008 #8

    malawi_glenn

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    Why make up when it already exist?
     
  10. May 12, 2008 #9

    malawi_glenn

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    The stuff that comes out of the proton, is the other two quarks (the ones that are not strucked by the incoming electron) are undergoing hadronisation since only colourless objects can exist in observable states.

    http://en.wikipedia.org/wiki/Hadronization
    http://en.wikipedia.org/wiki/Color_confinement

    http://hyperphysics.phy-astr.gsu.edu/hbase/particles/proton.html
     
  11. May 12, 2008 #10
    In fact, the theory seems to be crazy enough, because it works wondefully.
    If you throw an electron (lepton) on a hadron, and observe only the electron (lepton) recoiling, you can use a powerful theorem called the optical theorem, which in fact greatly simplify the situation. The total cross-section for the scattering in any non-zero direction is related (equal) to the imaginary part of the amplitude for forward scattering. Forward scattering is a process for which the initial state is the same as the final state. Of course it cannot be measured experimentally. But the wonder is that you can formally write down this forward amplitude in terms of things that depend only on the hadron structure that you wish to invetigate and not on the details of how you investigate it. That means, you can throw an electron or you can throw a muon for instance. You can throw a proton and anti-proton and search for di-lepton events (Drell-Yan). And the beauty of it is that you write down your cross-section in terms of the same universal structure functions describing your hadron and it works wonders. This is called deep inelastic scattering (DIS).

    Then you can even go further, and make more elaborate calculations for the probability to produce an additional particle, such as a pion for instance. You make your diagrams, where you take into account all the possibilities that this occurs, introducing new functions dubbed fragmentation functions, giving you the probability to produce such and such meson once you have pulled out such and such partonic configuration. And you invetigate in many different ways with many different reactions and once again it works perfectly fine with the same structure functions as before. This is called semi-inclusive DIS. "Inclusive" refers to the fact that you do not obeserve anything else than the lepton, and can use the optical theorem. "Semi-inclusive" means you observe more than just the lepton, but still sum over all the possible rest.

    This consistent picture has its own limitations, and today more and more people focus on exculsive reactions, where you observe everything. Those are significantly more challenging both experimentally and theoretically, but the reward is worth the additional trouble : this is the only way beyond DIS and brings you to measure instead of just probability distributions (structure functions), non-diagonal matrix element parameterizing quantum-correlations between partonic configurations in the hadrons. You can extract from those objects for instance the complete energy-momentum tensor of quarks/gluons inside the hadrons, leading you to understand how the spin is made from them (an outsdanding problem in hadronic physics), or even the distribution of forces/generalized pressure underwent by the partons, a concept which simply would not make sens a decade ago or so.
     
    Last edited: May 12, 2008
  12. May 12, 2008 #11

    If you haven't notice. Feyman call it "partrons". That means he somewhat disagree with the quarks theory. I mean we do know something exist, we just do not know exactly what it is.
     
  13. May 12, 2008 #12
    humanino, i need some times to digest your post. lol
     
  14. May 12, 2008 #13

    malawi_glenn

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    And if you haven't noticed, Feynman is dead long ago. The quark model of the protons and so on has been rewarded by nobel prize.

    https://www.physicsforums.com/showthread.php?t=230139

    http://nobelprize.org/nobel_prizes/physics/laureates/2004/public.html

    http://en.wikipedia.org/wiki/Parton_(particle_physics)

    Yesterday, you had no idea that one splitted the nucleons over 40years ago, and today you are telling me that we don't know what it is and that we have to make model and so on. That is quite strange..

    Partons was just a suggestion from feynman et al. wheras the quark theory was dealing with another side of hadron spectroscopy. Later, when QCD was borned and so on, one realised that the partons and quarks are the same thing.

    If you want a good intro book about elementary particle physics, I can recommend "Particle physics" by Martin & Shaw
     
    Last edited: May 12, 2008
  15. May 12, 2008 #14
    It's base on the info you gave me. The diagram show that a bunch of stuff come when collide. Next to the picture is Feynman and some other guy theory and model. I thought that quark theory come out long before that.
     
  16. May 12, 2008 #15

    malawi_glenn

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    Then you could have asked: "what is the difference between quarks and partons?" You just found out that one has splitted the nucleons, so perhaps take it piece by piece? ;)
     
  17. May 12, 2008 #16
    Oho, now I have to ask that question. Please, do the honor. hehe
     
  18. May 12, 2008 #17

    malawi_glenn

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