Semiclassical analysis of low lying eigenvalues. III. Width of the ground state band in strongly coupled solids: Barry Simon. Division of Mathematics, Physics and Astronomy, California Institute of Technology, Pasadena, California 91125

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 37 KB
• Volume: 158
• Category: Article
• ISSN: 0003-4916
• DOI: 10.1016/0003-4916(84)90249-5

✦ Synopsis

The known operator solution of the massless Schwinger model is used to calculate exactly, in three operator product expansions, the coefficient functions of the first few operators of low dimension which contribute when vacuum matrix elements are to be taken. A comparison of the results provides a test of the procedure used by M. A. Shifman, H. I. Vainshtein, and V. I. Zakharov, in their study of QCD. It is found that the shift in vacua does not affect the calculation of coefficient functions. The vacuum insertion approximation yields somewhat misleading estimates of vacuum expectation values of some composite operators; however, the standard method used to estimate the errors of vacuum insertion indicates that the approximation is unreliable in this model. Semiclassical Analysis of Low Lying Eigenvalues. III. Width of the Ground State Band in Strongly Coupled Solids.