Measurement of the decay Υ{hooked}′→Υ{hooked}π+π-

B. Niczyporuk*, T. Zełudziewicz, K. W. Chen, R. Hartung, G. Folger, B. Lurz, H. Vogel, U. Volland, H. Wegener, J. K. Bienlein, R. Graumann, J. Krüger, M. Leissner, M. Schmitz, F. H. Heimlich, R. Nernst, A. Schwarz, U. Strohbusch, H. J. Trost, P. ZschorschA. Engler, R. W. Kraemer, F. Messing, C. Rippich, B. Stacey, S. Youssef, A. Fridman, G. Alexander, A. Av-Shalom, G. Bella, Y. Gnat, J. Grunhaus, E. Hörber, W. Langguth, M. Scheer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We report the first observation of the decay Υ{hooked}′→Υ{hooked}π+π- →l+l-π+π-. The 7 events seen yield a branching ratio B(Υ{hooked}′→Υ{hooked}π+π- )=(19±8)%. A consistent value of B=(26±13)% is obtained from the charged multiplicities of the Υ{hooked}′ and Υ{hooked} decays. Using these values we deduce Γtot(Υ{hooked}′)=(31+10-8 ) keV and Bee(Υ{hooked}′)=(1.8±0.5)%. Furthermore we estimate Γ(Υ{hooked}′→ggΥ{hooked})=(10±5) keV in agreement with QCD predictions using vector gluons while one would expect 100 keV with scalar gluons.

Original languageEnglish
Pages (from-to)95-100
Number of pages6
JournalPhysics Letters B
Issue number1
StatePublished - 19 Mar 1981


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