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A Proposal About the Rest Masses of Quarks

  1. Apr 29, 2004 #1
    List of reccomended reading for string theory includes-
    'A Proposal About the Rest Masses of Quarks'
    by Jiao Lin Xu

    Using String Theory the rest mass of quarks is given as-
    u=930, d=930, s=1110, c=2270, b=5530

    The average rest mass of the figures given by the (international) Particle Data Group are
    u=0.003, d=0.00675, s=0.1175, c=1.2, b=4.25 GeV

    How do I make a comparison between these two statements?
  2. jcsd
  3. May 12, 2004 #2
    Maybe the problem is how to assign mass to quarks. There are different definitions for what you call mass in the case of quarks, and one must be careful not to speak too loosely about it. Notice that leptons have a very well defined mass, even though it might not be precisely measured (yet).

    One definition is the coefficient that appears in the Dirac part of the QCD lagrangian. This results in a renormalized mass, or "running mass", which is usually what one considers as the true mass for the quarks, and is called Standard Model mass.

    An other one is furnished by the quark model. This is a classical interpretation, as :
    Mass(composite object) = Sum[ Mass(constituents) ] + Binding_Energy (which is negative !)
    In my opinion, this is closer to what one determines in String theory. But this is doubtlessly flawed by the fact that the term Binding_Energy is meaningless here, at least on a classical level, because of confinement.

    There are still other definitions. In lattice QCD, the mass of the quarks are "bare mass", different from the running MS mass. These parameters are to be determined, so as to produce optimized numerical value for known quantities, such as meson mass.

    So, as a conclusion : do not expect anyone to give you a true value for the quark mass, unless first providing a correct definition for this quantity
  4. May 26, 2004 #3

    Only one reply but it proves that quality comes in small quantities; many thanks.
    Peter Woit's criticism of string theory included an objection to the string theory conclusion that there are an infinite number of fundamental particles. In my latest addition to my developement of a vacuum theory, I have added a piece on mass and charge. this not only shows a new way of relating quark masses but also that there is indeed (in theory) an infinite number of fundamental particles. It also shows in practicle terms why they are unlikely to exist in reality.
    To do this I have used the average mass for each quark calculated from the figures published by the Particle Data Group. The debate on my proposal is in the Theory Developement forum
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