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Department of Physics,National Taiwan University

Faculty(by Directory)

Er-Cheng Tsai

Name   蔡爾成
 Er-Cheng Tsai
Title   Associate Professor
Education   Ph.D., MIT (1985)
Office   522


  • Lecturer, Department of Mathematics, Massachusetts Institute of Technology
  • Assistant Professor, Department of Mathematics, Massachusetts Institute of Technology
  • Associate Professor, Department of Physics, National Taiwan University
We have accomplished the quantization of the non-Abelian gauge field theory on the basis of canonical quantization. The conventional path integral formalism is at best incomplete.In particular, We have found that the Feynman rules obtained via straightforward application of the Faddeev-Popov formalism are inconsistent in various gauge. In the case of Coulomb gauge, we showed that if the principal prescription for the gluon propagator is adopted, the ghost loops should be included in Feynman diagrams. We have also prove the equivalence between canonical formulation with ghost fields and that without ghost fields. Our quantization procedure, in contrast to the path integral approach, is nonperturbative in nature and yields the correct Feynman rules. The gauge invariance for other physical quantities in addition to the scattering matrix can be established.
Selected Publications
  1. Electron-Electron Scattering at High Energies and Fixed Angles; Phys. Rev. D27, 421 (1982).
  2. Delbruk Scattering; Phys. Rev. D26, 908 (1982).
  3. Photon-Photon Scattering at High Energy and Fixed Angles; Phys. Rev. D26, 922 (1982).
  4. Ghostless Feynman rules in Non-Abelian Gauge Theories; Phys. Rev. D34, 3858 (1986).
  5. Correspondence between Quantum Gauge Theories with Ghost Fields and Their Covariantly Quantized Theories with Ghost Fields; Physics Letter B176, 130 (1986).
  6. Inconsistency of Feynman Rules Derived via Path integration; Phys. Rev. Letter. 57, 511 (1986).
  7. Canonical Quantization of Non-Abelian Gauge Field Theory and Feynman Rules; Chinese Journal of Physics, Vol. 25, No 1, 95 (1987).
  8. The Quantum Wilson Loop; Phys. Rev. D/Nov. 15, 3196 (1987).
  9. The Meaning of the BRS Lagrangian Theory; Phys.Rev. D40, 1246 (1989).