Electroweak Calculations in the Presence of Nonperturbative QCD Effects
A momentum space Feynman rule is derived for the quark condensate insertion into Feynman amplitudes using the quark condensate component of the nonperturbative vacuum expectation value of the two nonlocal normal ordered quark fields. The lowest-order quark condensate component of the QCD nonperturbative quark self-energy is calculated, leading to a gauge independent dynamical component for the quark mass. Insertion of this nonperturbative order parameter into lowest-order electroweak quark self-energies is shown to satisfy on-mass-shell gauge parameter independence only if there is no contribution from the dynamical symmetry breaking parameter <|Psi Psi>. Dynamical contributions to the quark propagator, such as those from nonperturbative QCD leading to a dynamical quark mass, are shown to generate corrections to electroweak Green's functions in order to retain consistency with SU(2) times U(1) Ward identities. Such corrections lead to additional contributions to 3- and 4-point vertices which are annihilated by transverse projection operator, suggesting the utility of Landau gauge for calculations involving dynamical effects. The induced Yukawa coupling in the chiral limit is calculated, providing an example of a physical consequence of such externally generated corrections to electroweak Green's functions.
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- QUANTUM CHROMODYNAMICS;
- Physics: Elementary Particles and High Energy; Mathematics