K. Adachi

Measurement of inclusive particle spectra and test of MLLA prediction in e+e− annihilation at s=58Gev

Abstract Inclusive momentum spectra are measured for all charged particles and for each of π ± , K ± , K 0 K 0 , and p p in hadronic events produced via e + e − annihilation at s =58 Gev . The measured spectra are compared with QCD predictions based on the modified leading log approximation (MLLA). The MLLA model reproduces the measured spectra well. The energy dependence of the peak positions of the spectra is studied by comparing the measurements with those at other energies. The energy dependence is also well described by the MLLA model.

Measurement of the total hadronic cross section and determination of γ-Z interference in e+e− annihilation

Abstract The total hadronic cross section in e + e − annihilation was measured at s =5.77 GeV to be σ h = 143.6 ± 1.5 (stat) ± 3.5 (sys) pb with only the QED corrections. The measurement was based on data corresponding to an integrated luminosity of 90.8 pb −1 accumulated by the TOPAZ detector at TRISTAN. Our data point put stringent constraints on the size of the γ - Z 0 interference and the Z 0 mass. Combining our data with the OPAL data at LEP, we obtained the coefficient of the interference and the Z 0 mass to be J had = 0.10 ± 0.26 and M z = 91.151 ± 0.008 GeV, respectively, in a model-independent analysis.

Charged particle multiplicities of quark and gluon jets in e+ e- annihilation at TRISTAN

Abstract Charged-particle multiplicity was studied in e+e− annihilation at s = 57.8 GeV using the TOPAZ detector at TRISTAN. The average multiplicity was 〈nch〉 = 17.64± 0.05(stat.) ± 0.41(syst.). It was found that the multiplicity depends on the thrust (T) of an event. From extrapolating this relation to T = 2 3 , the multiplicity for three-fold symmetric events was estimated to be 〈n ch 〉 T = 2 3 = 23.50 −1.45 +1.25 . From this, the multiplicity ratio between gluon- and quark-jet was estimated to be r g q = 1.46 −0.13 +0.09 without any possible bias from jet clustering.

k0 (K̄0) production in two-photon processes at TRISTAN

Abstract We have carried out an inclusive measurement of K 0 ( K 0 ) production in two-photon processes at TRISTAN. The mean s was 58 GeV and the integrated luminosity was 199 pb−1. High-statistics Ks samples were obtained under such conditions as no-, anti-electron, and remnant-jet tags. The remnant-jet tag, in particular, allowed us, for the first time, to measure the cross sections separately for the resolved-photon and direct processes.

A study of single photon production in e+e− collisions at s=58 GeV with the TOPAZ detector at TRISTAN

Abstract We report a study of single photon production in e+e− collisions at s =58 GeV with the TOPAZ detector at TRISTAN. From data corresponding to an integrated luminosity of 213 pb−1, 5 single photon candidates remained after event selection, which can be compared with the expected 3.1 ν ν γ and 2.8 background events. These results exclude the selectron mass below 47.2 GeV at the 90% confidence level, if e L and e R are mass-degenerate and the photino is massless. When combined with results from other experiments, this limit improves to 75.0 GeV.

Measurement of the cross-section and forward-backward charge asymmetry for the b and c-quark in \(e^+e^-\) annihilation with inclusive muons at \(\sqrt{s} = 58\) GeV

Abstract. We have studied inclusive muon events using all the data collected by the TOPAZ detector at

Observation of excess Λ(Λ) production in two-photon processes at TRISTAN

\sqrt{s}=58

Observation of highly virtual photon-photon collisions to hadrons at TRISTAN

GeV with an integrated luminosity of 273pb

Measurement of the forward-backward asymmetries for charm- and bottom-quark pair productions at 〈S〉 = 58 GeV with electron tagging

^{-1}

Measurement of the jet width in γγ collisions and in e+e− annihilation process at TRISTAN

. From 1328 inclusive muon events, we measured the ratio