Gauge invariance in the presence of a cutoff

Journal Article · Thu Oct 15 04:00:00 EDT 2009 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.80.044004· OSTI ID:21293913

Kvinikhidze, A N ^[1]; Blankleider, B ^[2]; Epelbaum, E ^[3]; Hanhart, C ^[3]; Valderrama, M Pavon ^[3]

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1. A. Razmadze Mathematical Institute of Georgian Academy of Sciences, M. Alexidze Str. 1, 380093 Tbilisi, Georgia (United States)
2. Department of Physics, Flinders University, Bedford Park, South Australia 5042 (Australia)
3. 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, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 4 Vol. 80; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
EQUATIONS
FIELD THEORIES
GAUGE INVARIANCE
NUCLEONS
S MATRIX