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Quark masses

  1. Apr 24, 2006 #1


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    Is there anything in fundamental theory to explain the peculiarity of quark masses? The up and down have about the same mass, however for the other two pairs, there are big disparities, i.e. charm much bigger than strange and top much bigger than bottom.
  2. jcsd
  3. Apr 25, 2006 #2


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    As far as I know, there is nothing in the SM that would constrain quark and lepton masses. They are treated as free parameters that need to be obtained from experiment (plus a renormalization scheme). Even in string theory, my understanding is that there is not much achieved in that direction; there, you need to find out which topology of the extra dimensions would reproduce the mass spectra of observed particles, which basically means that the masses need also be obtained from experiment.
  4. Apr 25, 2006 #3
    All quark and lepton masses are free parameters in the Standard Model. There have certainly been many attempts to explain them with a more fundamental theory. People have constructed models that could explain various features of the observed particle spectrum, and some of those models are consistent with all known data, and hence could be true. However, since we have no positive evidence for physics beyond the Standard Model, this is all in the realm of speculation. The good news is that many models of this type are testable at the upcoming collider - the LHC. So, hopefully we'll soon have some more experimental insight into this question.
  5. May 6, 2006 #4
    i'm a new comer

    as far as i know, the masses of quarks can be calculated perturbatively by methods of chial symmetry breaking.:biggrin:
  6. May 7, 2006 #5


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    Yep, but in function of the masses of mesons, so you just change the question. :cool:

    Now, what is sad about all this mass stuff is that if the couplings of the elementary particles are confirmed to come down from hig energy GUT theories, then one needs a complicated differential equation to pinpoint precise values at working energies and one can even forget about the possibility of certain (ie of the order of experimental measure) prediction.
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