VOLUME 45, NUMBER 24 PHYSICAL REVIEW LETTERS 15 DECEMBER 1980 used the average of Z and A masses since these are degenerate at the spherical level. ') We have derived here a large number of quad- ratic mass relations which agree with experiment to about 1&o or better with essentially no free parameters. Earlier symmetry-breaking models, often quite accurate in restricted domains, can- not discriminate between quadratic and linear mass relations and, in fact, employ both. Our results' lend new support to the DTU ap- proach and to its ability to generate predictions in both the meson and baryon sectors through a well-defined sequence of approximations. 'G. F. Chew and V. Poenaru, Lawrence Berkeley Laboratory Report No. LBL-9768, 1979 (to be pub- lished). G. F. Chew and G. Rosenzweig, Phys. Rep. 41G, 263 (1978). See, e.g. , C. Schmid, D. M. Webber, and C. Soren sen, Nucl. Phys. B111, 317 (1976). We thank Dr. J. Finkelstein for comments on this point. 5H. M. Chan, J. Paton, and S. T. Tsou, Nucl. Phys. B86, 479 (1975). 6M. Ademollo, G. Veneziano, and S. Weinberg, Phys. Rev. Lett. 22, 83 (1969). We thank L. A. P. Balazs for pointing this out to us. See also L. A. P. Balazs and B. Nicolescu, to be published. Experimental Study of Heavy Charged Leptons and Search for Scalar Partners of Muons at PETRA (12 GeV ~E, ~36. 7 GeV) D. P. Barber, U. Becker, G. D. Bei, G. Berghoff, A. Boehm, J. G. Branson, J. Bron, D. Buikman, J. D. Burger, M. Capell, C. C. Chang, H. S. Chen, M. Chen, C. P. Cheng, Y. S. Chu, R. Clare, P. Duinker, G. Y. Fang, Z. Y. Feng, H. S. Fesefeldt, D. Fong, M. Fukushima, J. C. Guo, A. Hariri, G. Herten, M. C. Ho, T. T. Hsu, D. Z. Jiang, R. W. Kadel, W. Krenz, J. Li, Q. Z. Li, D. Luckey, E. J. Luit, C. M. Ma, D. A. Ma, , G. G. G. Massaro, T. Matsuda, H. Newman, M. Pohl, F. P. Poschmann, J. P. Revol, M. Rohde, H. Rykaczewski, I. Schulz, K. Sinram, M. Steuer, H. W. Tang, L. G. Tang, D. Teuchert, Samuel C. C. Ting, K. L. Tung, F. Vannucci, X. R. Wang, Y. X. Wang, J. Warnock, M. White, G. H. Wu, S. X. Wu, T. W. Wu, P. C. Yang, C. C. Yu, N. L. Zhang, and R. Y. Zhu III Physikalisches Institut, Technische IIochschule, D-51 00 drachen, ~est Germany, and Deutsches Elekty'onen- Synch&otyon, D-2000 IIambuxg 52, West Germany, and La bo~ato~y fox Xuclem" Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02239, and Nationaal Instituut voor Kernfysica en Hogh Energiefysica-, I 009 DB Amsterdam-, The ¹therlands, and Institute of High Energy Physics, Chinese Academy of Science, Pehing, People's Republic of China (Heceived 2 October 1980) Data from the MARK-J detector on the reactions e+e — p, +p, 7. +7 in the center-of- mass energy range from 12 to 36.7 GeV are presented. The p, 7. radii are shown to be &10 '6 cm. A search has been made for the production of a new heavy lepton and for the production of spin-0 supersymmetric partners of the muon. 95%-confidence-level lower limits of 16 GeV for the mass of a new charged heavy lepton and 15 GeV for the mass of the scalar partners of the muon are obtained. PACS numbers: 14. 60.-z, 13. 10. +q Since our previous publications in which we re- ported on the results of measurements of the re- actions e'e - )L(, 'ILf, and T'T in the center-of- mass energy range from 12 to 36.7 Ge&, further data have been collected. We report here on our latest results on the verification of the validity of quantum electrodynamics (QED) with p. , w leptons, on the search for more heavy leptons, and on the search for spin-0 supersymmetric partners of muons. The MARK- J detector and the method of detec- tion of muons and T leptons have been described previously. ' The data have been corrected for radiative effects' and detector acceptance. The resultant e 'e — p'p, and T'w cross sections, as a function of the c. m. energy vs, are plotted in Fig. 1 together with the QED predictions. The deviation of the measured cross section a from the QED prediction oQED is described with a form factor 5' such that o= oQEDF'(s), where E(s) =les/ 1904 1980 The American Physical Society