K. Königsmann

Limits on axion and light Higgs boson production in ϒ (1S) decays

Abstract We have searched for axion and light Higgs boson production in the channel ϒ (1 S ) → (a 0 or h 0 ) + γ , where the non-interacting axion a 0 and the Higgs boson h 0 do not decay in the detector. We find no evidence for an axion and give an upper limit, Br( ϒ (1S) → a 0 γ ) −5 (90% CL), for long-lived axions. Combining our limit with the previous search in J / ψ decays, we are able to rule out the axion in the standard model with first order QCD corrections. Our ϒ (1S) data also rule out a Higgs boson with mass m h

Search for exotic tau decays

Abstract The Crystal Ball detector at the Doris II storage ring at DESY was used to search for the exotic decay processes τ →e γ , τ →e π 0 , and τ →e η . No signal was observed. We obtained the following 90% CL upper limits on the branching fractions: B ( τ →e γ ) −4 , B ( τ →e π 0 ) −4 , B ( τ →e η ) −4 .

The Michel parameter for the decay τ→eνν

Abstract The Crystal Ball detector at the Doris II storage ring at DESY has been used to study the electron energy spectrum of the decay τ→evv. In the standard model the Lorentz structure of the decay matrix element is of the well known V-A type, resulting in a Michel parameter of p =0.75. Our spectrum is found to be consistent with this value. A fit yields the value of 0.64±0.07.

Measurement of π0 and η meson production in e+e- annihilation at {Mathematical expression} near 10 GeV

AbstractWe present a study of inclusive π0 and ŋ production ine+e− annihilation at

Measurement of €0€0 production in two-photon collisions

\sqrt s \approx 10 GeV

Spin analysis of the chi b states.

. Our analysis is based on integrated luminosities of 46.2 pb−1 taken at the υ (1 S) resonance and 42.1 pb−1 taken in the neighboring continuum. We measure the inclusive π0 and ŋ spectra for direct υ (1 S) → 3g decays and continuum processes

\chi(b

e^ + e^ - \to q\bar q