Measurement of the tau lepton lifetime

The mean lifetime of the tau lepton is measured in a sample of 25700 tau pairs collected in 1992 with the ALEPH detector at LEP. A new analysis of the 1-1 topology events is introduced. In this analysis, the dependence of the impact parameter sum distribution on the daughter track momenta is taken into account, yielding improved precision compared to other impact parameter sum methods. Three other analyses of the one- and three-prong tau decays are updated with increased statistics. The measured lifetime is 293.5+/-3.1+/-1.7 fs. Including previous (1989-1991) ALEPH measurements, the combined tau lifetime is 293.7+/-2.7+/-1.6 fs

A Roadmap for HEP Software and Computing R&D for the 2020s

Particle physics has an ambitious and broad experimental programme for the coming decades. This programme requires large investments in detector hardware, either to build new facilities and experiments, or to upgrade existing ones. Similarly, it requires commensurate investment in the R&D of software to acquire, manage, process, and analyse the shear amounts of data to be recorded. In planning for the HL-LHC in particular, it is critical that all of the collaborating stakeholders agree on the software goals and priorities, and that the efforts complement each other. In this spirit, this white paper describes the R&D activities required to prepare for this software upgrade.Peer reviewe

Integrated-Transformer-Based Impedance Matching Method: Impedance Matching With Transformers

Impedance matching is a critical aspect of any RF or millimeter-wave (mm-wave) design. Although historically addressed with transmission lines or discrete elements, it can also be implemented with integrated transformers as their quality factors now reach decent values (approximately 10–20) at high frequencies (used at 77 GHz in this article) due to the thicker upper metal layers present in most integrated stacks

Baseband TIA Design Using Inversion Coefficient MOSFET Model in CMOS 28nm

This paper presents a design methodology to size a transimpedance amplifier for an automotive radar receiver. Based on the Enz-Krummenacher-Vittoz (EKV) MOSFET model, it presents the essential equations to develop a small-signal model featuring a limited number of parameters, which can be exploited to quickly explore the different design optimums of a circuit. Post-layout simulations are presented to validate the model and the methodology. The designed TIA presents a gain of 65 dBΩ, a bandwidth of 80 MHz, an input impedance of 74 Ω and input-referred noise of 50 yA2.Hz−1

A Roadmap for HEP Software and Computing R&D for the 2020s

Particle physics has an ambitious and broad experimental programme for the coming decades. This programme requires large investments in detector hardware, either to build new facilities and experiments, or to upgrade existing ones. Similarly, it requires commensurate investment in the R&D of software to acquire, manage, process, and analyse the shear amounts of data to be recorded. In planning for the HL-LHC in particular, it is critical that all of the collaborating stakeholders agree on the software goals and priorities, and that the efforts complement each other. In this spirit, this white paper describes the R&D activities required to prepare for this software upgrade

Heavy flavour production in Z decays

From an analysis of inclusive leptons in data collected by the ALEPH detector at LEP, we measure the fractions of b and c events in hadronic Z decays. The b fraction times semileptonic branching ratio is measured to be . Assuming a b semileptonic branching ratio of 0.102 ± 0.010 gives , in good agreement with the standard model prediction of 0.217. The c fraction times semileptonic branching ratio is measured to be . Assuming a c semileptonic branching ratio of 0.090 ± 0.013 gives , in agreement with the standard model prediction of 0.171

A Precise measurement of Gamma (Z ---> b anti-b) / Gamma (Z ---> hadrons)

A measurement of the partial width ratio using a method which tags the decays through the lif etime of the produced heavy hadrons is presented. This method relies on the tracking precision afforded by a double-sided silicon vertex detector. The tag algorithm makes a probabilistic interpretation of three-dimensional track impact parameters, using the data to measure the resolution. By tagging the two b hadrons separately, both and the tag efficiency can be determined from the data. For a 26% efficiency of tagging a single b hadron within the vertex detector solid angle coverage, a purity of 96% is achieved. A value of is found. Combining this result with other recent ALEPH measurements gives a 95% confidence upper limit on the Standard Model top mass of Mt < 228 GeV

Studies of QCD in e+ e- ---> hadrons at E(cm) = 130-GeV and 136-GeV

Studies of QCD in \mbox{e}^+\mbox{e}^- \rightarrow Hadrons at $E_{cm} =$} 130 and 136 GeV The ALEPH Collaboration An analysis of the properties of hadronic final states produced in electron-positron annihilation at centre-of-mass energies of 130 and 136 GeV is presented. The measurements are based on a data sample of 5.7 \mbox{pb}^{-1} collected in November 1995 with the \Aleph detector at LEP. Inclusive charged particle distributions, jet rates and event-shape distributions are measured and the results are compared with the predictions of QCD-based models. From the measured distributions quantities are determined for which the dependence on the centre-of-mass energy can be predicted by QCD, including the mean multiplicity of charged particles, the peak position of the inclusive distribution of $\xi = -\ln x_p$ ($x_p = p / p_{beam}$), and the strong coupling constant $\alpha_s$. The QCD predictions are tested by comparing with corresponding measurements at $E_{cm} = 91.2$ GeV and at lower energies