0000000000331909
AUTHOR
D. Sacco
Search for the t and b' quarks in hadronic decays of the Z0 boson
We present a search for the third generation up type quark t and a possible fourth down type quark b' in hadronic Z0 decays observed in DELPHI at the LEP collider. For any scenario with a decay through the charged current or into a charged Higgs with a mass at least 6 GeV/c2 below the t and 3 GeVc2 below the b' mass, we set a lower limit for the t quark mass at 44.0 GeV/c2 and for the b' mass at 44.5 GeV/c2. For specific scenarios the mass limits are slightly higher, e.g. for charged current decays the limits are 44.5 and 45.0 GeV/c2 respectively, where all limits are given at a 95% confidence level. © 1990.
Influence of comorbidity and cognitive status on instrumental activities of daily living in amnestic mild cognitive impairment: results from the ReGAl project.
Objectives To investigate whether amnestic mild cognitive impairment (aMCI) is characterised by restriction in instrumental activities of daily living (IADL). Further, to examine the role of comorbidity and cognitive performance on IADL changes in aMCI subjects. Methods The study included 132 subjects with aMCI and 249 subjects with no cognitive impairment (NCI), consecutively enrolled as outpatients in a multicentric Italian clinical-based study, the ReGAl Project. All subjects underwent a comprehensive evaluation including clinical examination, laboratory screening, neuroimaging and cognitive and behavioral assessments. Functional status was evaluated by the Lawton's Instrumental Activiti…
Search for heavy charged scalars in Z$^0$ Decays
Using a sample of Z0's corresponding to about 12 000 events, we have searched for the production of charged scalars, primarily charged Higgs particles, decaying into c̄scs̄, τν+jets, and τντν. The average detection efficiency is 20%. No candidate was found in the leptonic modes. Masses in the range up to 30-36 GeV/c2 are excluded, extending the mass domain covered by previous e+e- machines.
Control of enteric neuromuscular functions by purinergic P2X7 receptors in normal rat distal colon and experimental bowel inflammation
Introduction: Purinergic signalling plays a pivotal role in the physiological regulation of several enteric functions, as well as in the modulation of immune/inflammatory cell activity. Recent evidence has shown an active involvement of the purinergic P2X7 receptor (P2X7R) in the fine tuning of immune functions, as well as its critical role in driving enteric neuron apoptosis under intestinal inflammation. However, the participation of this receptor pathway in the regulation of enteric neuromuscular functions remains undetermined. Aims: This study investigated the role of P2X7Rs in the control of colonic motility, both under normal conditions and in the presence of experimental colitis. Met…
Search For Light Neutral Higgs Particles Produced In Z0-decays
A search for the neutral Higgs boson in Z0-decays has been performed using the DELPHI detector at the Large Electron Positron collider (LEP) at CERN. We looked for the decay of Z0 into a neutral Higgs particle and a pair of fermions. No events fulfilled the criteria for H0-production. Our results, which are based on an integrated luminosity of 530 nb-1, exclude a minimal Standard Model Higgs boson with a mass in the range 210 MeV/c2 to 14 GeV/c2 at 95% confidence level.
A precise measurement of the Z resonance parameters through its hadronic decays
A measurement of the cross section for e+e-→ hadrons using 11 000 hadronic decays of the Z boson at ten different center-of-mass energies is presented. A three-parameter fit gives the following values for the Z mass MZ, the total width ΓZ, the product of the electronic and hadronic partial widths ΓeΓh, and the unfolded pole cross section σ0: MZ = 91.171 ± 0.030 (stat.) ± 0.030 (beam) GeV, ΓZ = 2.511 ± 0.065 GeV, ΓeΓh = 0.148 ± 0.006 (stat.) ± 0.004 (syst.) GeV2, σ0 = 41.6 ± 0.7 (stat.) ± 1.1 (syst.) nb, Good agreement with the predictions of the standard model is observed. From a two-parameter fit the number of massless neutrino generations is found to be Nv = 2.91 ± 0.26. Thus the hypothes…
Study of the leptonic decays of the Z0 boson
Measurements are presented of the cross section ratios Rℓ = σℓ(e+e-→ℓ+ℓ -)/σhh(e+e-→hadrons) for ℓ = e, μ and τ using data taken from a scan around the Z0. The results are Re = (5.09±0.32±0.18)%, Rμ = (4.96±0.35±0.17)% and Rτ,=(4.72±0.38± 0.29)% where, for the ratio Re, the t-channel contribution has been subtracted. These results are consistent with the hypothesis of lepton universality and test this hypothesis at the energy scale s ∼ 8300 GeV2. The absolute cross sections σℓ(e+e-→ℓ +ℓ-) have also been measured. From the cross sections the leptonic partial widths Γe = (83.2±3.0±2.4) MeV, (ΓeΓμ) 1/2=(84.6±3.0±2.4) MeV and (ΓeΓτ) 1/2=(82.6±3.3±3.2) MeV have been extracted. Assuming lepton un…