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Up & down quarks

  1. May 29, 2015 #1
    Is there a simple explanation for why up & down quarks have different charge?
  2. jcsd
  3. May 29, 2015 #2


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    When "quarks" were invented by Gell-Mann and Zweig, they were simply associated the charges (2/3 elementary charges for the up, -1/3 for the down quark) such that the correct charge pattern for the hadrons resulted. See,


    for the SU(3)-constituent-quark model.

    Nowadays this charge pattern, together with the 3 colors of the color SU(3) underlying QCD, make the Standard Model consistent in avoiding a chiral anomaly of the weak gauge group ##\mathrm{SU}(2)_{\text{wiso}} \times \mathrm{U}(1)_{\text{Y}}.##
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