The ratio {ital R} of the total cross section for {ital e}{sup +}{ital e}{sup {minus}} annihilation into hadrons to the lowest-order QED cross section for {ital e}{sup +}{ital e}{sup {minus}}{r ...arrow}{mu}{sup +}{mu}{sup {minus}} has been measured for center-of-mass energies ranging from 50 to 61.4 GeV. If we allow for an overall shift of {minus}4.9%, about 1.5 times our estimated normalization error, the results are consistent with the standard-model predictions.
We present the charged-particle multiplicity distributions for {ital e}{sup +}{ital e}{sup {minus}} annihilation at center-of-mass energies from 50 to 61.4 GeV. The results are based on a data sample ...corresponding to a total integrated luminosity of 30 pb{sup {minus}1} obtained with the AMY detector at the KEK storage ring TRISTAN. The charged-particle multiplicity distributions deviate significantly from the modified Poisson and pair Poisson distributions, but follow Koba-Nielsen-Olesen scaling and are well reproduced by the LUND parton-shower model.
A search for the pair production of charged Higgs particles decaying via the {ital H}{sup {minus}}{r arrow}{tau}{bar {nu}} mode has been made in {ital e}{sup +}{ital e}{sup {minus}} annihilations at ...center-of-mass energies between 50 and 60.8 GeV using the AMY detector at the KEK collider TRISTAN. No evidence for their existence is observed and 95%-C.L. mass limits are presented. The result has been interpreted in terms of the tan{beta} parameter in the Higgs sector.
