N. Iida

Measurement of the inclusive cross section of jets in γγ interactions at TRISTAN

Abstract We have investigated the properties of jet production in almost real γγ collisions at √s=58 GeV with the TOPAZ detector at the TRISTAN e+e− collider. The data were analyzed with a jet-clustering method based on a cone algorithm. The jet rate shows evidence for a hard scattering effect of the hadronic constituents of a photon (resolved photon processes). We have also observed a substantial energy flow in the small-angle region, which is additional evidence for resolved photon processes. We present the transverse momentum dependence of the inclusive jet and two-jet cross sections and compare them with different model predictions.

Measurement of the D ± Cross Section using a Soft-Pion Analysis in Two-Photon Processes

Abstract The differential cross section of dσ(e + e − → e + e − D ∗± X) dP T was measured using a soft-pion analysis D ∗± → π s ± D 0 (D 0 ) at TRISTAN. The average s was 58.7 GeV and the integrated luminosity used in this analysis was 198 pb − , respectively.

Measurement of the photon structure function F2γ and jet production at TRISTAN

Abstract We have measured the photon structure function F2γ in the reaction e+e− → e+e− hadrons for average Q2 values from 5.1 to 338 GeV2 by using data collected by the TOPAZ detector at TRISTAN. The data have been corrected for detector effects and are compared with theoretical expectations based on QCD. The structure function F2γ increases as ln Q2, as expected. A sample of events with one or two distinct jets has been identified in the final state. Although two-jet events can be explained solely by the point-like perturbative part, one-jet events require a significant hadron-like part in addition.

Measurements of αs in e+e- annihilation at /TRISTAN

Abstract The strong coupling constant α s was determined from analyses of the thrust, heavy jet mass and, differential 2-jet rate, using e + e - hadronic events at s = 58 GeV with the TOPAZ detector at TRISTAN. The NLLjet Monte Carlo simulation (NLLjet) and analytic formulae based on resummation up to the next-to-leading logarithms combined with O ( α 2 s ) calculations were used to evaluate α s . The average α s values at Q 2 = (58 GeV) 2 from the analyses are α s = 0.125 ± 0.009 for NLLjet and α s = 0.132 ± 0.008 for the resummed analytic formulae.

Measurement of inclusive electron cross section in γγ collisions at TRISTAN

関連論文有。 nMeasurement of inclusive electron cross section in γγ collisions at TRISTAN n M. Iwasaki et al: Physics Letters B, Vol. 341, Issue 1, pp. 99–108. nhttp://www.sciencedirect.com/science/article/pii/0370269394013497

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.

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.

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

Measurement of the forward-backward asymmetry of e+e− → ccat √s = 57.95 GeV

GeV with an integrated luminosity of 273pb