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Particle Physics Question: Strong interaction

  1. May 24, 2016 #1
    1. The problem statement, all variables and given/known data
    In electromagnetic interactions, the force carrier is the photon, and it interacts with anything which has electric charge. Electric charge can be represented by the integers on a single number line and photons themselves carry no electric charge.
    (a) In the case of the strong interaction, explain what is analogous to the number line representing electric charge in electromagnetism.
    (b) Do gluons carry the charge associated with the strong interaction?
    (c) What important feature of the strong interaction follows from your answer to (b)?

    2. Relevant equations


    3. The attempt at a solution
    (a) The colour charge associated with gluons? (this is the one i'm not sure of, what does this mean?)
    (b) Yes- colour charge
    (c) Colour charge is conserved in strong interactions.

    Thanks for any help with a), and if the other are correct.
     
  2. jcsd
  3. May 24, 2016 #2

    mfb

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    Right. For (a), you can be more precise. Can you draw color charges on a line like you can with electric charges where you have integers?
    Why would that follow from gluons carrying color charge? Photons do not carry electric charge, but electric charge is conserved.
    Color charge is conserved, but that is not the result of (b).
     
  4. May 24, 2016 #3
    For (a), I think you can, in the sense that there are 8 possible colours for gluons so it's discrete up to a point?
    and for (c) Is this getting at the fact that as gluons carry colour charge, they have self interactions, unlike photons?

    Thanks again, forever grateful!
     
  5. May 24, 2016 #4

    mfb

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    The gluons are not the point. What about the color charges themself? Is there a color charge "1"?
    Yes, self-interaction is the first point, but you can add a second step. What is an important consequence of the self-interaction?
     
  6. May 25, 2016 #5
    For (a) There are 6 colour charges, red, green and blue and their anti's, but with electric charge theres, for example, +1 or -1 which are the same kind of charge differing in sign. But with colour charge, they are different? Is this maybe getting at as there are 6 types (3 and their anti's) so you can represent them on 3 number lines of integer colour charge?

    For (c) Is it that gluon-gluon interactions leads to quarks being bound in hadrons and they cannot exist in free states on their own? I don't really understand why this is, I have just read it.
     
  7. May 25, 2016 #6

    mfb

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    It goes in the right direction, but you also have gluons with one color and one anticolor, or quarks with a superposition of colors, so you need more than just the three lines. Not more lines, but something ... bigger.
    Yes. Self-interaction alone is not sufficient for this, but it is the critical point.
     
  8. May 25, 2016 #7
    Is it some kind of coordinate system or matrix? Then you could effectively 'plot' where the points are? Thank you for all the help by the way, I only have half a page of notes on gluons/strong interaction from lectures and most of this stuff isn't covered.
     
  9. May 25, 2016 #8

    mfb

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    You can treat the colors as coordinates in space, that is the main point. You are not limited to the axes.
     
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