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Whats the difference between colour and flavour?

  1. May 21, 2008 #1
    basically, what is it?
    also, is there such a thing as "colour change"?

    ahh, i have PHY3 tomorrow i can't believe i still don't get this
     
  2. jcsd
  3. May 21, 2008 #2
    Hi funnybunny
    The colour and flavour are two different types of charges if you will, just as mass and electric charge are different. Flavour refers to the weak interaction properties, whereas colour refers to the strong interaction.

    Colour is probably simpler to begin with. Quarks carry colour charge, but the leptons have vanishing colour charge. Therefore, leptons do not undergo strong interactions. Quarks exchange gluons which allows them to change their colour. If you will, quarks can be red, blue or green, and gluons carry composite types of colour, like red-antiblue. A red quark can thus turn blue by emitting such a gluon, and a blue quark would turn red by absorbing such a gluon. This is a bit simplified but not too crazy description of the underlying group theory business.

    Flavor is less simple. There are three generations in the standard model. The first generation is made up of (in terms of lepton pair/quark pair) electron-Eneutrino/up-down members, the second of muon-Mneutrino/strange-charm, and the third of tau-Tneutrino/bottom-top. Bottom is sometimes refered to as "beauty", and also rarely top is refered to as "truth". The flavour quantum numbers let you know where you are in this classification. The group theory here again is not so trivial, you need to actually specify some combinations of the above numbers, like (weak-)hypercharge/(weak-)isospin.

    Good luck :smile:
     
    Last edited: May 21, 2008
  4. May 21, 2008 #3

    blechman

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    color is the strong nuclear force analog of "charge" in E&M. things that have color (quarks and gluons) can interact through said force.

    flavor is the "name" of the particle in question. The key aspect to flavor is mass: particles of different flavor have different masses; particles of the same flavor have the same mass. Example: electrons and muons have different "flavor" and hence different mass. But a top quark and a top quark have the same flavor and hence the same mass (!)

    Again, as humanino says, there are subtleties. For example: strong and electromagnetic (and gravity) forces can NOT change the flavor of a particle, whereas the weak nuclear force can. Thus any "decay" of a (fundamental) particle necessarily involves the weak nuclear force.
     
  5. May 22, 2008 #4

    arivero

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    flavour is not a local gauge symmetry.
     
  6. May 22, 2008 #5

    blechman

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    well, it is if you ask people trying to solve the flavor puzzle! :wink: but it certainly isn't in the "standard model"
     
  7. May 22, 2008 #6

    arivero

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    Ah but remember I solved the flavor puzzle :cool:
     
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