T. Kojima

Evidence for hard scattering of hadronic constituents of photons in photon-photon collisions of TRISTAN

Abstract We present results of an experimental study of e + e − + hadrons in the kinematic regime for which the process is interpreted as hadron production in collisions of almost-real photons. The data sample corresponds to an integrated luminosity of 27.5 pb − and covers center-of-mass energies from 55 to 61.4 GeV. We observe more events than expected from the incoherent sum of quark-parton and vector-meson-dominance models, and we give a quantitative explanation of the excess by including the hard scattering of the hadronic constituents of the photons calculated with QCD.

A measurement of the photon structure function F2

Abstract The photon structure function F2 has been measured at average Q2 values of 73,160 and 390 ( GeV c ) 2 . We compare the x dependence of the Q2 = 73 ( GeV c ) 2 data with theoretical expectations based on QCD. In addition we present results on the Q2 evolution of the structure function for the intermediate x range (0.3⩽ x ⩽0.8). The results are consistent with QCD.

A measurement of the photon structure function F2γ at Q2 = 6.8 GeV2

The photon structure function F-2(gamma) has been measured at an average Q(2) value of 6.8 GeV2 using data collected by the AMY detector at the TRISTAN e(+)e(-) collider. The measured F-2(gamma) is compared with several QCD-based parton density models

A search for leptoquark and colored lepton pair production in e+e- annihilations at TRISTAN

Abstract We report on a search for the pair production of leptoquarks and colored leptons in e + e − annihilations t center-of-mass energies from 50 to 60.8 GeV, using the AMY detector at TRISTAN. No evidence for such particles is found and 95% CL mass limits are given.

Measurement of α s using NLLA+O( α S 2 ) in e + e − annihilation at s=58.0 GeV

Abstract A measurement of the strong coupling constant α S is presented using hadronic events produced in e + e − annihilations at s =58.0 GeV from the AMY detector at TRISTAN. The measurement is based on comparisons of the distributions of thrust, heavy jet mass, total jet broadening, wide jet broadening, and energy-energy correlations with QCD calculations resummed up to next-to-leading-logarithms matched with the O ( α S 2 ) perturbative calculation. Combining the results of the individual evaluations, we find α S (58 GeV )=0.132±0.006 .