Gauge invariance in the presence of a cutoff
- A. Razmadze Mathematical Institute of Georgian Academy of Sciences, M. Alexidze Str. 1, 380093 Tbilisi, Georgia (United States)
- Department of Physics, Flinders University, Bedford Park, South Australia 5042 (Australia)
- Forschungszentrum Juelich, Institut fuer Kernphysik (IKP-3) and Juelich Center for Hadron Physics, D-52425 Juelich (Germany)
We use the method of gauging equations to construct the electromagnetic current operator for the two-nucleon system in a theory with a finite cutoff. The employed formulation ensures that the two-nucleon T-matrix and corresponding five-point function, in the cutoff theory, are identical to the ones formally defined by a reference theory without a cutoff. A feature of our approach is that it effectively introduces a cutoff into the reference theory in a way that maintains the long-range part of the exchange current operator; for applications to effective field theory (EFT), this property is usually sufficient to guarantee the predictive power of the resulting cutoff theory. In addition, our approach leads to Ward-Takahashi (WT) identities that are linear in the interactions. From the point of view of EFT's where such a WT identity is satisfied in the reference theory, this ensures that gauge invariance in the cutoff theory is maintained order by order in the expansion.
- OSTI ID:
- 21293913
- Journal Information:
- Physical Review. C, Nuclear Physics, Vol. 80, Issue 4; Other Information: DOI: 10.1103/PhysRevC.80.044004; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- English
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