Light-front Ward-Takahashi identity and current conservation
Nov 1, 2007
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Abstract: (APS)
We construct a conserved electromagnetic current for two-boson systems in finite mass boson exchange models within light-front dynamics. For that purpose, we use a quasipotential reduction to perform the three-dimensional light-front projection of the 4-dimensional current operator. The electromagnetic current operator acting on the valence component of bound and scattering states can be perturbatively calculated in the quasipotential expansion, in correspondence with a truncation of the Fock space. The divergence of the proposed current operator satisfies a Ward-Takahashi identity at any given order of the quasipotential expansion. Also shown is the relation between the three-dimensional light-front reduction of the field-theoretic Bethe-Salpeter amplitudes and current for bound and scattering states with the 4-dimensional ones. The matrix elements of the 4-dimensional current operator can be fully recovered from the corresponding light-front ones. In one test case the theoretical framework is realized explicitly.- 11.40.-q
- 21.45.+v
- 11.10.St
- 13.40.-f
- Ward-Takahashi identity: light front
- current: conservation law
- current: operator
- quasipotential
- Bethe-Salpeter equation
- current: electromagnetic
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