The Case of ${\alpha }_s$: $Z$ versus Low Energies, or How Nature Prompts us of New Physics

Abstract

The values of ${\alpha }_s$ determined from low- and high-energy measurements are in irreconcilable contradiction with each other. The current status of the problem is critically reviewed. Consequences of the ${\alpha }_s$ contradiction, in conjunction with other anomalies detected at the $Z$ peak, are discussed. The write-up is updated in accordance with experimental numbers reported at summer conferences.

Comments: Talk at the International Symposium on Particle Theory and Phenomenology (XVIII Kazimierz Meeting on Particle Physics and 1995 Madison Phenomenology Symposium), Iowa State University, Ames, May 22 - 24, 1995. Latex file, 34 pages; 6 figures included as eps files; additional 3 figures are available upon request. Three references added, minor modifications