.Using the Crystal Ba.11 detector a.t the eSestorage ring DORIS II, we ha.ve mea.sured the branching fra.ction to muon pairs B,, of the Y(lS) and T(2S) resonances and for the first time the product of the muonic pa.rtiaI width IYPP and the branching fra.ction to electrons. B,, for both resonances. We obtain %m) = (2.31 f 0.12 f 0.10) % I’,,(lS).B,,(lS) = (31.2 f 1.6 zt 1.7) eV .a.nd 4w(W = (1.22 f 0.28 f 0.19) % I’,,(2S)-B,,(2S) = (6.5 31 1.5 f 1.0) eV. Inserting the present world a.vera.ge va.lue of B,,(lS) = (2.52 & 0.17) %, we determine the muonic partiaI width of the Y(lS) as TPP(lS) = (1.24 f 0.06 zt 0.11) keV. In a.ddition, we present the first indication of the expected interference between p-pair production in the continuum a.nd in T(lS) deca.ys. (Submitted to Zeitschrift fur Physik) a) Present Address: Max-Planck-Institut ftir Physik, D-W8000 MGnchen 40, Germany ‘J Perma.nent Address: DPHPE, Centre d’Eiudes Nucleaires de Saclay, F-91191 Gif sur Yvette, Fra.nce ‘1 Permanent Address: CERN, CH-1211 Genkve 23, Switzerland dJ Permanent Address: Institute of Physics and Nuclear Techniques, AGH, PI,-30055 Cracow, Poland eJ Supported by the U.S. De a d by the Natronal Science P artment of Energy, contract No. DE-AC03-81ER40050 ffS oundation, grant No. PHY75-22980 upported by the National Science Foundation, grant No. PHY85-12145 9) Supported by the U.S. Department of Energy, contra.ct No. DE-AC02-76ER03066 hJ Supported by the German Bundesministerium fiir Forschung und Technologie, contract No. 054 ER 12P .?Supported by the German Bundesministerium ftir Forschung und Technologre, contract No. 054 HH llP(7) XT d by the Deutsche Forschungsgemeinschaft Supported by the U.S. Department of Energy, contract No. DE-AC02-76ER03064 ‘J Supported by FOM-NW0 *) Supported by the U.S. Department of Energy, contract No. DE-AC02-76ER.03072 d by the National Science Foundation No. 054 WU I lF’( 1)

We have investigated the hadronic transitions \ensuremath{\Upsilon}(2S)\ensuremath{\rightarrow}${\ensuremath{\pi}}^{0}$${\ensuremath{\pi}}^{0}$\ensuremath{\Upsilon}(1S)\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\gamma}l +${l}^{\mathrm{\ensuremath{-}}}$ (l=\ensuremath{\mu} or e) and \ensuremath{\Upsilon}(2S)\ensuremath{\rightarrow}${\ensuremath{\pi}}^{+}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\Upsilon}(1S)\ensuremath{\rightarrow}${\ensuremath{\pi}}^{+}$\ensuremath{\pi} $^{\mathrm{\ensuremath{-}}}e^{+}$${e}^{\mathrm{\ensuremath{-}}}$ using the Crystal Ball detector at the DESY ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ storage ring DORIS II. Using the present world-average value of ${B}_{\mathrm{ll}}$(\ensuremath{\Upsilon}(1S))=2.9\ifmmode\pm\else\textpm\fi{}0.3)% we derive branching ratios B(\ensuremath{\Upsilon}(2S)\ensuremath{\rightarrow}${\ensuremath{\pi}}^{0}$${\ensuremath{\pi}}^{0}$\ensuremath{\Upsilon}(1S))= (8.0\ifmmode\pm\else\textpm\fi{}1.5)% and B(\ensuremath{\Upsilon}(2S)\ensuremath{\rightarrow}${\ensuremath{\pi}}^{+}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\Upsilon}(1S))= (16.9\ifmmode\pm\else\textpm\fi{}4.0)%. We also present results on the invariant-mass spectra and the angular distributions of the dipion system.

The Crystal Ball detector at the e+ e- storage ring DORIS-II has been used to search for radiative B meson decays, especially of the type b --> s-gamma. No monoenergetic gamma-lines have been found in the inclusive photon spectrum from UPSILON(4S) decays, and upper limits are obtained for radiative decays of B mesons to various strange mesons and to the D*. Integrating the photon spectrum over the corresponding energy range, we find BR (B--> gamma-X) < 2.8 x 10(-3), at 90% confidence level for the mass range 892 MeV less-than-or-equal-to M(X) less-than-or-equal-to 2045 MeV.

The reaction e+ e- --> e+e- eta-pi(0)pi(0) --> e+ e- 6-gamma has been analysed using the full data sample taken with the Crystal Ball detector at the DORIS II storage ring at DESY. The eta-pi(0)pi(0) invariant mass spectrum is dominated by the eta', for which we determine the radiative width GAMMA(gamma-gamma)(eta') to be (4.5 +/- 0.3 +/- 0.5) keV. Near 1.9 GeV/c2 we observe a second enhancement in the eta-pi(0)pi(0) mass distribution. Assuming that these events are created by the production and subsequent decay of a wide resonance X(1900), we have investigated the decay modes, the invariant mass distributions of the eta-pi(0) and pi(0)pi(0) subsystems and the angular distributions of the final state mesons. We find that the data is best described by J(PC) = 2-+. For this J(P) assignment the resonance parameters are GAMMA(gamma-gamma)(X) BR (X --> eta-pi-pi) = (0.95 +/- 0.27 +/- 0.20) keV, GAMMA(tot)(X) = (221 +/- 92 +/- 44) MeV, and M(X) = (1881 +/- 32 +/- 40) MeV/c2.

The reactione+e- →e+e- ηπ0π0→e+e- 6γ has been analysed using the full data sample taken with the Crystal Ball detector at the DORIS II storage ring at DESY. The ηπ0π0 invariant mass spectrum is dominated by the η', for which we determine the radiative width Γγγ(η') to be (4.5±0.3±0.5)keV. Near 1.9 GeV/c2 we observe a second enhancement in the ηπ0π0 mass distribution. Assuming that these events are created by the production and subsequent decay of a wide resonanceX(1900), we have investigated the decay modes, the invariant mass distributions of the ηπ0 and π0π0 subsystems and the angular distributions of the final state mesons. We find that the data is best described byJPC=2∓. For thisJP assignment the resonance parameters are Γγγ(X) BR(X→ηππ)=(0.95±0.27±0.20) keV Γtot (X)=(221±92±44)MeV, andM(X)=(1881±32±40) MeV/c2.

The Crystal Ball detector at the DORIS II storage ring at DESY has been used to measure the branching ratios for the decay modes x±-~h±n°v and x+-~h±n°n°v, where h ± is any charged hadron. The results are BR(x±-,h±n°v)=(2 2.0_+0.8- + 1.9)%, BR (x ± ~h ± n°n°v) = (5.7 _+ 0.5_+ I~ 7)% The first result is in good agreement with the present world average. The decay mode h ± n°n°v is reconstructed in x decays for the first time. Its branching ratio, however, is somewhat lower than the corresponding world average, and therefore tends to increase the one-prong problem.

The Crystal Ball detector a.t the t+~-storage ring DORIS II has been used t.o analyze exclusive semileptonic decays of B mesons produced at Y(4S) energies. The decay B + ev D* has been observed wit,h a branching ratio of (i.0 i 1.8 i 1.4)% using the no D decay mode of the D'. In addit,ion we have searched for the exclusive semileptonic decay B; + e&y no. We find an upper limit on BR(B' + e*, r ") of 0.22 % at, the 90% CL. Using the predictions of Bauer et al. this can be converted into an upper limit. of 0.015 for lV,,l.

The Crystal Ball detector has been used at the DORIS II storage ring at DESY to study the reactionγγ→π0π0π0 in theπ0π0π0 invariant mass range from 850 MeV/c2 to 2600 MeV/c2. An enhancement around 1750 MeV/c2 is attributed to theπ2(1670) resonance. The observedπ0π0 invariant mass distribution and theπ0 angular distributions are consistent with those expected for the decay chainπ2→π0f2(1270)→π0π0π0. From our measurements we find the following resonance parameters: two photon partial width\(\Gamma _{\pi _2 }^{\gamma \gamma } = (1.41 \pm 0.23 \pm 0.28)keV\), massM(π2)=(1742±31±49)MeV/c2. and total width\(\Gamma _{\pi _2 }^{tot} = (236 \pm 49 \pm 36)MeV\).

The Crystal Ball detector at thee+e− storage ring DORIS II has been used to analyze exclusive semileptonic decays ofB mesons produced at γ(4S) energies. The decayB→evD* has been observed with a branching ratio of (7.0±1.8±1.4)% using theπ°D decay mode of theD*. In addition we have searched for the exclusive semileptonic decayB±→e±vπ0. We find an upper limit onB±→e±vπ0 of 0.22% at the 90% CL.

The Crystal Ball detector at thee+e− storage ring DORIS II has been used to analyze exclusive semileptonic decays ofB mesons produced at γ(4S) energies. The decayB→evD* has been observed with a branching ratio of (7.0±1.8±1.4)% using theπ°D decay mode of theD*. In addition we have searched for the exclusive semileptonic decayB±→e±vπ0. We find an upper limit onB±→e±vπ0 of 0.22% at the 90% CL.

The production ofJ/ψ inB meson decays has been measured on the Γ(4S) resonance using the Crystal Ball detector at thee+e− storage ring DORIS II. TheJ/ψ is identified by itse+e− decay mode. We obtain a branching ratio of BR(B→J/ψX)=(1.12±0.33±0.25)% in good agreement with theoretical predictions based on color suppression. TheJ/ψ momentum distribution is observed to be peaked at high values. This implies a substantial contribution from directB meson decays to theJ/ψ. In addition upper limits onJ/ψ production in Γ(1S) and Γ(2S) decays and in continuum processes are determined.