Determination of the electronic branching ratio of the ϒ(9.46) and an upper limit for its total width

• Published in: Physics letters. B Vol. 93; no. 4; pp. 497 - 499
• Main Authors: Berger, Ch, Lackas, W., Raupach, F., Wagner, W., Alexander, G., Bürger, J., Criegee, L., Dehne, H.C., Devenish, R., Flügge, G., Franke, G., Gerke, Ch, Hackmack, E., Harms, P., Horlitz, G., Knies, G., Lehmann, E., Stella, B., Thompson, R.L., Timm, U., Waloschek, P., Winter, G.C., Wolff, S., Zimmermann, W., Achterberg, O., Blobel, V., Boesten, L., Daumann, H., Garfinkel, A.F., Kapitza, H., Koppitz, B., Lührsen, W., Maschuw, R., Spitzer, H., Van Staa, R., Wetjen, G., Bäcker, A., Derikum, K., Grupen, C., Meyer, H.J., Neumann, B., Zech, G., Daum, H.J., Meyer, H., Meyer, O., Rössler, M., Wacker, K.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.1980
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/0370-2693(80)90374-3

We have measured the reaction e + e − → e + e − at the ϒ Using athe excess of electron pairs over the QED expectation we obtain an electronic branching ratio of B ee = (5.1 ± 3.0) %. Combining this with publishe values of the muonic branching ratio B μμ we conclude that the ϒ is a narrow state with a total width < 180 keV at 95% C.L.