Investigation of the splitting of quark and gluon jets

The splitting processes in identified quark and gluon jets are investigated using longitudinal and transverse observables. The jets are selected from symmetric three-jet events measured in Z decays with the Delphi detector in 1991-1994. Gluon jets are identified using heavy quark anti-tagging. Scaling violations in identified gluon jets are observed for the first time. The scale energy dependence of the gluon fragmentation function is found to be about two times larger than for the corresponding quark jets, consistent with the QCD expectation TeX . The primary splitting of gluons and quarks into subjets agrees with fragmentation models and, for specific regions of the jet resolution TeX , with NLLA calculations. The maximum of the ratio of the primary subjet splittings in quark and gluon jets is TeX . Due to non-perturbative effects, the data are below the expectation at small TeX . The transition from the perturbative to the non-perturbative domain appears at smaller TeX for quark jets than for gluon jets. Combined with the observed behaviour of the higher rank splittings, this explains the relatively small multiplicity ratio between gluon and quark jets

Search for Neutral Heavy Leptons Produced in Z Decays

Weak isosinglet Neutral Heavy Leptons ($\nu_m$) have been searched for using data collected by the DELPHI detector corresponding to $3.3\times 10^{6}$ hadronic~Z$^{0}$ decays at LEP1. Four separate searches have been performed, for short-lived $\nu_m$ production giving monojet or acollinear jet topologies, and for long-lived $\nu_m$ giving detectable secondary vertices or calorimeter clusters. No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio $BR($Z$^0\rightarrow \nu_m \overline{\nu})$ of about $1.3\times10^{-6}$ at 95\% confidence level for $\nu_m$ masses between 3.5 and 50 GeV/$c^2$. Outside this range the limit weakens rapidly with the $\nu_m$ mass. %Special emphasis has been given to the search for monojet--like topologies. One event %has passed the selection, in agreement with the expectation from the reaction: %$e^+e^- \rightarrow\ell \bar\ell \nu\bar\nu$. The results are also interpreted in terms of limits for the single production of excited neutrinos

Measurement of the Quark and Gluon Fragmentation Functions in Z0Z^0 Hadronic Decays

The fragmentation functions and multiplicities in $b\overline{b}$ and light quark events are compared. The measured transverse and longitudinal components of the fragmentation function allow the gluon fragmentation function to be evaluated

Tuberculose cutânea disseminada com escrofuloderma associado à tuberculose de arco costal

Os autores relatam caso de tuberculose cutânea disseminada com escrofuloderma associado à tuberculose de arco costal. Paciente de 46 anos, do sexo feminino, há um ano com nódulos de um a 6cm em região cervical, dorso, axilas e regiões glúteas, que culminavam com fistulização e eliminação de secreção purulenta, associados a febre vespertina diária, sudorese noturna e emagrecimento de 10kg nos últimos três meses. A radiografia de tórax mostrou lesão lítica na terceira costela esquerda. A cultura de secreção do nódulo foi positiva para Mycobacterium tuberculosis. O tratamento para tuberculose resultou em melhora clínica e resolução das lesões cutâneas da paciente

Measurement of the e+ e- ---> gamma gamma (gamma) cross-section at the LEP energies

The total and the differential cross-sections for the reaction $e^+e^-\rightarrow \gamma\gamma(\gamma)$ have been measured with the DELPHI detector at LEP % with at centre-of-mass energies from 1 30 %, 136, 161, 172 and to 183 GeV for an integrated luminosity of 78.19.~pb$^{-1}$. %CR An agreement with the QED predictions was found and consequently The results agree with the QED prediction s. The lower limits (obtained including previously published results at the \Zzero energies) on the QED cutoff parameters are $\Lambda_{+} > 253$~GeV and $\Lambda_{-} > 225$~GeV and the lower bo und on the mass of an excited electron with an effective coupling constant $\lambda_{\gamma} = 1$ is 231~GeV/$c^2$. %Upper limits on the branching ratios for the decays ${\rm Z}^0\rightarrow$, ${\rm Z}^0\rightarrow \pi^0\gamma$, % ${\rm Z}^0\rightarrow \eta\gamma$ %and ${\rm Z}^0\rightarrow \gamma\gamma\gamma$ have been determined to be 2.5 % $\times$ $10^{-5}$, 2.5 $\times$ $10^{-5}$, % 4.0 $\times$ $10^{-5}$, %and 9.1 $\times$ $10^{-4}$ respectively. All the limits are at the 95$\%$ confidence level

Search for neutral and charged Higgs bosons in e+e−e^+ e^- collisions at s=161GeV\sqrt{s}= 161 GeV and 172GeV172 GeV

A search for neutral and charged Higgs bosons has been performed in the data collected by the {\sc DELPHI} detector at centre-of-mass energies of 161~GeV and 172~GeV. The analysis assumes either the pair-production of charged Higgs bosons, ${\mathrm H}^{\pm}$, or the production of the lightest neutral Higgs boson, h, with either a Z or a neutral pseudoscalar Higgs boson, A. All final state topologies expected from the decay of h and A %neutral Higgs particles into hadrons or a pair of $\tau$ leptons, and from the decay of ${\mathrm H}^{\pm}$ %charged Higgs bosons into a pair of quarks or a $\tau \nu_{\tau}$ pair have been considered. %In the case of the associated production with a Z boson, all decay %channels of the Z have been considered. %The case of a %Higgs boson decaying into invisible products has also been studied. %The results are interpreted %in the framework of the Standard Model and of its minimal supersymmetric %extension for the neutral Higgs bosons. %Results for the charged Higgs particles are deduced in the more %general two-doublet scheme. Lower limits at the 95\% confidence level have been obtained on the Higgs boson masses. The limits are 66.2~GeV/$c^2$ for h in the Standard Model, 59.5~GeV/$c^2$ for h and 51.0~GeV/$c^2$ for A in the minimal supersymmetrpseudosca