## An exam in Subnuclear PhysicsJanuary 9, 2009

Posted by dorigo in physics.
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• Draw the strong and electromagnetic coupling constants as a function of $Q^2$, explain their functional dependence using feynman graphs of the corrections to the photon and gluon propagators, write their formula, and compute the value of the constants at $Q^2=M_Z^2$, given the values at $Q^2=1 MeV^2$ (QED) and $Q^2=1 GeV^2$ (QCD).