M. Minowa

Experimental Investigation of the Energy Dependence of the Strong Coupling Strength

The energy dependence of the relative production rate of three-jet events is studied in hadronic e+e− annihilation events at center of mass energies between 22 and 46.7 GeV. Three-jet events are defined by a jet finding algorithm which is closely related to the definition of resolvable jets used in O(αs2) perturbative QCD calculations, where the relative production rate of three-jet events is roughly proportional to the size of the strong coupling strength. The production rates of three-jet events in the data decrease significantly with increasing centre of mass energy. The experimental rates, which are independent of fragmentation model calculations, can be directly compared to theoretically calculated jet production rates and are in good agreement with the QCD expectations of a running coupling strength. The hypothesis of an energy independent coupling constant can be excluded with a significance of four standard derivations.

Observation of planar three-jet events in e+e− annihilation and evidence for gluon bremsstrahlung

Abstract Topological distributions of charged and neutral hadrons from the reaction e+e− → multihadrons are studied at √s of about 30 GeV. An excess of planar events is observed at a rate which cannot be explained by statistical fluctuations in the standard two-jet process. The planar events, mostly consisting of a slim jet on one side and a broader jet on the other, are shown actually to possess three-jet structure by demonstrating that the broader jet itself consists of two collinear jets in its own rest system. Detailed agreement between data and predictions is obtained if the process e + e − →q q g is taken into account. This strongly suggests gluon bremsstrahlung as the origin of the planar three-jet events. By comparison of the data with the qqg-model we obtain a value for the strong coupling constant of αS(q2 = 0.17 ± 0.04.

Direct search for solar axions by using strong magnetic field and x-ray detectors

We have searched for axions which could be produced in the solar core by exploiting their conversion to X rays in a strong laboratory magnetic field. The signature of the solar axion is an increase in the rate of the X rays detected in a magnetic helioscope when the sun is within its acceptance. From the absence of such a signal we set a 95% confidence level limit on the axion coupling to two photons

Total cross section for hadron production by e+e− annihilation at petra energies

g_{a\gamma\gamma}\equiv 1/M < 6.0\times 10^{-10}

EXPERIMENTAL-STUDY OF JETS IN ELECTRON-POSITRON ANNIHILATION

GeV

Search for solar axions with mass around 1 eV using coherent conversion of axions into photons

^{-1}

Measurement of the property of cooled lead molybdate as a scintillator

, provided the axion mass

Test of Quantum Electrodynamics at {PETRA}

m_a<0.03

A measurement of the electroweak induced charge asymmetry in e+e−→bb̄☆

eV. The limit on the coupling is factor 4.5 more stringent than the recent experimental result. This is the first experiment whose sensitivity to

Dark matter search experiment with CaF2(Eu) scintillator at Kamioka Observatory

g_{a\gamma\gamma}