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Proof for Gauge Independence of the Energy‐Momentum Tensor in Quantum Electrodynamics
Author(s) -
Kashiwa Taro,
Tanimura Naoki
Publication year - 1997
Publication title -
fortschritte der physik/progress of physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.469
H-Index - 71
eISSN - 1521-3978
pISSN - 0015-8208
DOI - 10.1002/prop.2190450503
Subject(s) - physics , brst quantization , gauge anomaly , supersymmetric gauge theory , gauge covariant derivative , gauge fixing , introduction to gauge theory , mathematical physics , tensor (intrinsic definition) , gauge theory , quantum electrodynamics , hamiltonian lattice gauge theory , stress–energy tensor , mathematical descriptions of the electromagnetic field , quantum mechanics , gauge boson , mathematics , exact solutions in general relativity , geometry
Proof is given for gauge independence of the (Belinfante's) symmetric energy‐momentum tensor in QED. Under the covariant LSZ‐formalism it is shown that expectation values, supplemented with physical state conditions, of the energy‐momentum tensor are gauge independent to all orders of the purturbation theory (the loop expansion). A study is also made, in terms of the gauge invariant operators of electron (known as the Dirac's or Steinmann's electron) and photon, in expectation of gauge invariant result without any restriction. It is, however, shown that singling out gauge invariant quantities is merely synonymous to fixing a gauge, then there needs again a use of the asymptotic condition to obtain gauge independent results.