K.L. Tung

Hadron calorimetry in the L3 detector

Abstract The characteristics of the L3 hadron calorimeter as realized in the observation of hadronic jets and other events from e + e − collisions at LEP are presented and discussed. The pattern-recognition algorithm utilizing the fine granulatiry of the calorimeter is described, and the observed overall resolution of 10.2% for hadron jets from Z decay is reported. The use of the calorimeter in providing information on muon energy losses is also noted.

New particle searches

Abstract PETRA, the e + e − collider, has operated at a maximum CM energy of 46.78 GeV. We update our previous results on new particle searches and set significantly better mass limits on some.

Experimental Study of Inclusive Muon Spectra at PETRA

The results of a high-statistics study of inclusive muon spectra at PETRA are reported. Improved mass limits have been obtained for heavy quarks, heavy leptons, and charged Higgs particles. It is shown that the fragmentation properties of b quarks and c quarks are different, with the mean fragmentation variables = 0.75 +- 0.03 +- 0.06, = 0.46 +- 0.02 +- 0.05 and the average semileptonic branching ratio for the B and C hadrons BR(B) = (10.5 +- 1.5 +- 1.3)%, BR(C) = (11.5 +- 1.0 +- 1.7)%.

Physics with high energy electron-positron colliding beams with the MARK J detector

Abstract This report reviews the experimental investigation of high energy e + e − interactions by the MARK J collaboration at PETRA, the electron-positron colliding beam accelerator at DESY in Hamburg, Germany. The physics objectives include studies of several purely electromagnetic processes and hadronic final states, which further our knowledge of the nature of the fundamental constituents and of their strong, electromagnetic and weak interactions. Before discussing the physics results, the main features and the principal components of the MARK J detector are discussed in terms of design, function, and performance. Several aspects of the on-line data collection and the off-line analysis are also outlined. Results are presented on tests of quantum electrodynamics using e + e − → e + e − , μ + μ − and τ + τ − , on the measurement of R , the ratio of the hadronic to the point-like muon pair cross section, on the search for new quark flavors, on the discovery of three jet events arising from the radiation of hard noncollinear gluons as predicted by quantum chromodynamics, and on the determination of the strong coupling constant α s .

Search for Charged Higgs, Scalar Taus, and a Test of Technicolor Models

Abstract We have used our measurements of final states from e+e− containing an isolated muon and a hadronic or electron shower to search for new spin 0 charged particles. We exclude (95% CL) a supersymmetric partner of the τ with a mass less than 14 GeV/c2. We obtain upper limits on the branching ratio to τvτ for charged Higgs particles or technipions with masses up to 14 GeV/c2. This disagrees with some technicolor model predictions.

Search for SUSY particles γ̃, ṽ, ẽ, W̃ in electron positron annihilation at 44 GeV

We study the production of single γ, e and μ at high πt using the high energy data of the Mark-J detector at PETRA. We find good agreement with QED. We give mass limits of the SUSY particles γ, v, e and W studying the associated production of W and ẽ and radiative production of pairs of γ or v in three-body reactions.

Search for SUSY particles γ̃, ṽ, ẽ, W̃ in electron positron annihilation at 44 GeV☆

We study the production of single γ, e and μ at high πt using the high energy data of the Mark-J detector at PETRA. We find good agreement with QED. We give mass limits of the SUSY particles γ, v, e and W studying the associated production of W and ẽ and radiative production of pairs of γ or v in three-body reactions.

Search for {SUSY} Particles Photino, Sneutrino, Selectron, Wino in Electron Positron Annihilation at 44-{GeV}

We study the production of single γ, e and μ at high πt using the high energy data of the Mark-J detector at PETRA. We find good agreement with QED. We give mass limits of the SUSY particles γ, v, e and W studying the associated production of W and ẽ and radiative production of pairs of γ or v in three-body reactions.