H. J. Daum

Observation of a Narrow Resonance Formed in e+ e- Annihilation at 9.46-GeV

Abstract An experiment using the PLUTO detector has observed the formation of a narrow, high mass, resonance in e+e− annihilations at the DORIS storage ring. The mass is determined to be 9.46±0.01 GeV which is consistent with that of the Upsilon. The gaussian width σ is observed as 8±1 MeV and is equal to the DORIS energy resolution. This suggests that the resonance is a bound state of a new heavy quark-antiquark pair. An electronic width Γee=1.3±0.4 keV was obtained. In standard theoretical models, this favors a quark charge assignment of 1 3 .

Study of atmospheric neutrino interactions with the Fréjus detector

Abstract We present an analysis of the neutrino event sample recorded in the Frejus experiment. This sample which corresponds to the 1.56 kt yr final sensitivity of the experiment is compared to the predictions of a Monte Carlo neutrino simulation program. It is based on a recent calculation of the atmospheric neutrino flux at the Frejus latitude which takes into account muon polarization effects. The comparison is performed on the distributions of the visible energy, the zenith angle and the neutrino flavor. Good agreement is obtained between the data and the simulation within statistics.

Jet analysis of the ϒ(9.46) decay into charged hadrons

Abstract The direct decay into four and more charged particles of the ϒ(9.46) formed in e+e− collisions is analysed for hadron-jet configurations. The results are compared with the expectations of phase space, a q q two-jet model and a QCD three-gluon decay mechanism. Out of these three models, the three-gluon decay describes best the data.

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

Abstract 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

Results from the Fréjus experiment for nucleon decay modes into anti-neutrino + meson

Abstract With the Frejus 900 ton calorimeter (550 ton fiducial), a search for nucleon decay events into anti-neutrino plus meson has been performed. No signal is found for a sensitivity of 1.3 kiloton × year. Lower lifetime limits for various decay modes range from 0.9 to 2.9 10 31 years (at 90% C.L.).

Measurement of leptonic branching ratios of the Γ(9.46)

The electronic width Γee and the muonic branching ratioBμμ=Γμμ/Γtot of the Γ(9.46) have been measured as Γee=(1.33±0.14) andBμμ=(2.2±2.0)%. From these values a lower limit of Γtot<23keV for the total width of the Γ(9.46) is obtained.

Results from the Fréjus experiment on nucleon decay modes with charged leptons

Lower limits on the nucleon lifetime in channels containing at least one positron or muon are given. The analysis is based on 4 years of data taking with the Fréjus detector. Various approaches to determine the background from atmospheric neutrinos are discussed and two different nuclear models are used in event simulations. The limits obtained range from 1031 years forp→e+K*0 to 1.5·1032 years forp→e+K*0 to 1.5·1032 years forp→µ+γ.

A search for high energy neutrinos from SN 1987A, the Carb, Hercules X-1, and Cygnus X-3 with the Fréjus detector

AbstractWith the Fréjus detector we studied four astrophysical point-like sources by usingn

Experimental determination of υ background expected in the Fréjus nucleon decay detector

v_e (bar v_e )