6 research outputs found
LIFETIME MEASUREMENT OF CHARM MESONS PRODUCED IN pi- p AND p p INTERACTIONS AT 360-GeV/c
No full textResults are presented on charm meson lifetimes. The sample of charm particle decays was obtained by exposing the high resolution rapid cycling hydrogen bubble chamber (LEBC) coupled with the European Hybrid Spectrometer to π− and p beams at 360 GeV/c from the CERN SPS. The analysis of ∼850 k pictures has yielded 77 events containing a total of 60 charm decays. From these, an unbiased sample of 31 D decays (15± and 16 D0) is issued in the lifetime analysis. The measured mean lifetimes for D± and D0 are (where the symbol D0 means D0 and D0):τ(D±)=8.4+3.5−2.2 × 10−13sτ(D0)=4.1+1.3−0.9 ×10−13s. Three unambiguous examples of F± decay have also been observed and the corresponding lifetime, based on 2 decays, is τ(F±)=2.1 +3.6−0.8 × 10 −13
Inclusive φ production in K+p interactions at 70 GeV/c
No full textWe present results on inclusive φ meson production in K+p interactions at 70 GeV/c in the kaon fragmentation x>0.2 region. Comparison with other data on φ meson production in K± and p induced reactions provides evidence that the strange valence-quark fragmentation or recombination processes play the dominant role in the K±→φ transitions. Arguments are presented that the kaon valence strange s-quark carries a much higher momentum fraction than the u-quark. Evidence for the previously observed narrow φπ+ state at mass ∼2.1 GeV is discussed. © 1982.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Scaling in the semi-inclusive reactions K+p → K♀n (charged) + anything at 5, 8.2 and 16 GeV/c
No full textWe study the scaling properties of the semi-inclusive reactions K+p → K0 + n (charged) + X0 (neutral) measuring the momentum spectra of K0-mesons for a given number of prongs n. Distributions of the particle density ω(dσn/dpL)/σn for the inclusive K0 at n = 2 and n = 4 show evidence for limited scaling at 5.0, 8.2 and 16 GeV/c incident K+ momenta. © 1972.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
MEASUREMENT OF THE MASS AND WIDTH OF THE Z0 PARTICLE FROM MULTI - HADRONIC FINAL STATES PRODUCED IN e+ e- ANNIHILATIONS
No full textFirst measurements of the mass and width of the Z0 performed at the newly commissioned LEP Collider by the DELPHI Collaboration are presented. The measuements are derived from the study of multihadronic final states produced in e+e- annihilations at several energies around the Z0 mass. The values found for the mass and width are M(Z0)=91.06±0.09 (stat) ±0.045 (syst.) GeV and Γ(Z0)=2.42±0.21 (stat.) GeV respectively, froma three-parameter fit to the line shape. A two-parameter fit in the framework of the standard model yields for the number of light neutrino species Nν=2.4±0.4 (stat.) ±0.5 (syst.)0SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Search for the Standard Model Higgs boson at LEP.
No full textThe four LEP Collaborations, ALEPH, DELPHI, L3 and OPAL, have collected a total of 2461 pb−1 of e+e− collision data at centre-of-mass energies between 189 and 209 GeV. The data are used to search for the Standard Model Higgs boson. The search results of the four Collaborations are combined and examined in a likelihood test for their consistency with two hypotheses: the background hypothesis and the signal plus background hypothesis. The corresponding confidences have been computed as functions of the hypothetical Higgs boson mass. A lower bound of 114.4 GeV/c2 is established, at the 95% confidence level, on the mass of the Standard Model Higgs boson. The LEP data are also used to set upper bounds on the HZZ coupling for various assumptions concerning the decay of the Higgs boson
