Limits on the production of scalar leptoquarks from Z (0) decays at LEP

A search has been made for pairs and for single production of scalar leptoquarks of the first and second generations using a data sample of 392000 Z0 decays from the DELPHI detector at LEP 1. No signal was found and limits on the leptoquark mass, production cross section and branching ratio were set. A mass limit at 95% confidence level of 45.5 GeV/c2 was obtained for leptoquark pair production. The search for the production of a single leptoquark probed the mass region above this limit and its results exclude first and second generation leptoquarks D0 with masses below 65 GeV/c2 and 73 GeV/c2 respectively, at 95% confidence level, assuming that the D0lq Yukawa coupling alpha(lambda) is equal to the electromagnetic one. An upper limit is also given on the coupling alpha(lambda) as a function of the leptoquark mass m(D0)

Bestimmung des schwachen Mischungswinkels sin"2#THETA#_e_f_f aus der Ladungsasymmetrie hadronischer Zerfaelle des Z-Bosons

Final results are presented on the measurement of the charge asymmetry of hadronic decays of the Z using the full data samples of about 300.000 events collected with the DELPHI experiment at LEP in 1990 and 1991. The asymmetry has been obtained with two different approaches, which are based on a momentum weighted charge sum to determine the jet charge in the two hemispheres. From the observed asymmetry the Minimal Standard model parameter sin"2\Thetaeff has been derived to the sin"2\Thetaeff = 0.2335+0.0047-0.0035. Within the framework of the Minimal Standard model this result provides a determination of the top quark mass of mTop = 12990-...(exp.)+21-22 (mHiggs GeV. Alternatively, by including the measurement of the total hadronic width of the Z the effective vector and axial-vector couplings of the Z can be extracted to give ga = -0.4998#+-#0.0021 and g#upsilon# -0.0331+0.0094-0.0070. Comparisons with other experimental results and predictions of the standard model give no hint for necessary extensions of the Minimal Standard model. (orig.)SIGLEAvailable from TIB Hannover: RO 9740(92-10) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Search for pair production of neutral Higgs bosons in Z0 decays

This paper explores a participatory process between a Law lecturer, an academic literacy practitioner and students as teacher agency was conceptualised and theorised as a means of promoting student success. This position paper identifies and advocates a shift in the role of the lecturer as discipline expert to practitioner to provide students with the much needed community of practice (Wenger 1998) and to bridge the gap between epistemological access to disciplines (Morrow 1993) and student identity. This investigation is premised on the notion that students are usually identified as the only ones lacking in effective academic practices; little attention is given to lecturers’ reluctance or inability to embrace methodologies that make disciplinary practices explicit to students to enable them to become academically literate in the discourse of the university as well as their specialist disciplines. The study draws on interviews with the lecturer and focus group discussions with students. Informed by the theories of New Literacy Studies, Rhetorical Studies and Threshold Concepts, the paper presents the notion of ‘crossing the threshold’ from discipline or content expert to discipline practitioner. The paper suggests that it is through intense and sustained critical conversations between the discipline expert, student and academic literacy practitioner that the role of the lecturer may shift to a shared space where academic literacy is embedded in the methodological practices governing the pedagogy of the discipline. It is also suggested that higher education provide the opportunity and scaffolding for lecturers to move into an academic development role within the parameters of their own faculties and disciplines

A Search for sleptons and gauginos in Z0 decays

Using a data sample corresponding to 10 000 hadronic Z0 decays, we have searched for the production of sleptons and gauginos in the two-prong decays of Z0. No candidate remains after straightforward selections. For neutralinos, we use selection methods developed in our previous search for neutral Higgs particles. The negative results are translated into improved mass limits and parameter constraints on the minimal supersymmetric extension of the standard model