Absolute mass lower limit for the lightest neutralino of the MSSM from e+e−e^{+}e^{-} data at s\sqrt{s} up to 209 GeV

Charginos and neutralinos are searched for in the data collected by the ALEPH experiment at LEP for centre-of-mass energies up to 209 GeV. The negative result of these searches is combined with those from searches for sleptons and Higgs bosons to derive an absolute lower limit of 43.1 GeV/c(2) on the mass of the lightest supersymmetric particle (LSP), assumed to be the,lightest neutralino. This limit is obtained in the framework of the MSSM with R-parity conservation and with gaugino and sfermion mass unification at the GUT scale and assuming no mixing in the stau sector. The LSP limit degrades only slightly to 42.4 GeV/c(2) if stau mixing is considered. Within the more constrained framework of minimal supergravity, the limit is 50 GeV/c(2)

Constraints on anomalous QGC's in e+e−e^{+}e^{-} interactions from 183 to 209 GeV

The acoplanar photon pairs produced in the reaction e(+) e(-) - → vvyy are analysed in the 700 pb(-1) of data collected by the ALEPH detector at centre-of-mass energies between 183 and 209 GeV. No deviation from the Standard Model predictions is seen in any of the distributions examined. The resulting 95% C.L. limits set on anomalous QGCs, a(0)(Z), a(c)(Z), a(0)(W) and a(c)(W), are -0.012 lt a(0)(Z)/Lambda(2) lt +0.019 GeV-2, -0.041 lt a(c)(Z)/Lambda(2) lt +0.044 GeV-2, -0.060 lt a(0)(W)/Lambda(2) lt +0.055 GeV-2, -0.099 lt a(c)(W)/Lambda(2) lt +0.093 GeV-2, where Lambda is the energy scale of the new physics responsible for the anomalous couplings

Measurement of the inclusive D∗+−D*^{+-} production in γγ\gamma \gamma collisions at LEP

The inclusive production of D*/sup +or-/ mesons in two-photon collisions is measured with the ALEPH detector at e/sup +/e- centre- of-mass energies from 183 GeV to 209 GeV. A total of 360 +or- 27 D*+or- meson events are observed from an integrated luminosity of 699 pb/sup -1/. Contributions from direct and single-resolved processes are separated using the ratio of the transverse momentum p/sub t//sup D*+or-/ of the D*/sup +or-/ to the visible invariant mass W/sub vis/ of the event. Differential cross sections of D*+or- production as functions of p/sub t//sup D*+or-/ and the pseudorapidity ¿ eta D*/sup +or-/¿ are measured in the range 2 GeV/c =197 GeV/ = 731 +or- 74/sub stat/ +or- 47/sub Syst/ +or- 157/sub extr/ pb. (21 refs)

T-Type Multilevel Inverters: A Comparative Performance Analysis

T-type multilevel inverters are a potential alternative because of their increased efficiency and low conduction losses. T-Type topology is formed by adding a bidirectional switch to a conventional two-level inverter. There are a few T-Type MLIs formulated based on requirements and applications. This work provides a comparative analysis of three different T-Type five-level MLIs with a five-level cascaded H-Bridge converter. Four multi-carrier pulse width modulation (PWM) techniques, i.e., phase disposition (PD) PWM, phase opposition disposition (POD) PWM, alternate phase opposition disposition (APOD) PWM, and Hybrid PWM schemes are implemented to evaluate the performance of these MLIs. They are operated over a wide range of modulation indices, and the converter output voltage, total harmonic distortion (THD), and characteristics are observed. MATLAB\Simulink environment is used for this comparative performance analysis

Electroweak measurements in electron–positron collisions at w-boson-pair energies at lep

Contains fulltext : 121524.pdf (preprint version ) (Open Access