221 research outputs found
SEARCH FOR THE t AND b-prime QUARKS IN HADRONIC DECAYS OF THE Z0 BOSON
No full textWe 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. © 1990.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe
A study of intermittency in Hadronic Z Decays
No full textA study on the modifications of the relation between author and lector due to the translation from text to hypertex
MEASUREMENT OF THE AVERAGE LIFETIME OF B-HADRONS
No full textThe average lifetime of B hadrons produced in hadronic Z0 decays has been measured with the DELPHI detector at LEP. The measurement is based on the analysis of the impact parameter distribution of high p(t) muons and hadrons. The resulting mean B lifetimes are tau(B) = (1.30 +/- 0.10 +/- 0.08) ps and tau(B) = (1.27 +/- 0.04 +/- 0.12) ps respectively, giving a combined value of tau(B) = (1.28 +/- 0.10) ps. The hadronic sample was also used to measure the partial Z0 width GAMMA(bbBAR)/GAMMA(h) and gave a value of 0.222(-0.031)+0.033 +/- 0.017
MULTIPLICITY DEPENDENCE OF MEAN TRANSVERSE-MOMENTUM IN E+E- ANNIHILATIONS AT LEP ENERGIES
No full textA strong increase of the mean transverse momentum [p(t)] with the number of charged particles n(ch) is observed in e+e- annihilations into hadrons at LEP energies, The effect resembles correlations observed in hadron-hadron interactions. In e+e- annihilations the [p(t)] and n(ch) correlations can be accounted for by gluon radiation
Search for Leptoquarks and FCNC in e+ e- annihilations at S**(1/2) = 183-GeV
No full textA search for events with one jet and at most one isolated leptonused data taken at LEP-2 by the DELPHI detector.These data were accumulated at a center-of-mass energy of183 GeV and correspond to an integrated luminosity of47.7 pb.Production of single scalar and vector leptoquarkswas searched for. Limits at 95\% confidence level werederived on the masses (ranging from to for electromagnetic type couplings) and couplings of the leptoquark states.A search for top-charm flavour changing neutral currents( or charge conjugate) used the semileptonic decay channel. A limit on the flavour changing cross-section vianeutral currents was set at 0.55pb (95\% confidence level).A search for events with one jet and at most one isolated lepton used data taken at LEP-2 by the DELPHI detector.These data were accumulated at a center-of-mass energy of 183 GeV and correspond to an integrated luminosity of 47.7 1/pb. Production of single scalar and vector leptoquarks was searched for. Limits at 95% confidence level were derived on the masses (ranging from to for electromagnetic type couplings) and couplings of the leptoquark states.A search for top-charm flavour changing neutral currents( or charge conjugate) used the semileptonic decay channel. A limit on the flavour changing cross-section via neutral currents was set at 0.55pb (95% confidence level).A search for events with one jet and at most one isolated lepton used data taken at LEP-2 by the DELPHI detector.These data were accumulated at a center-of-mass energy of 183 GeV and correspond to an integrated luminosity of 47.7 1/pb. Production of single scalar and vector leptoquarks was searched for. Limits at 95% confidence level were derived on the masses (ranging from to for electromagnetic type couplings) and couplings of the leptoquark states.A search for top-charm flavour changing neutral currents( or charge conjugate) used the semileptonic decay channel. A limit on the flavour changing cross-section via neutral currents was set at 0.55pb (95% confidence level).A search for events with one jet and at most one isolated lepton used data taken at LEP-2 by the DELPHI detector.These data were accumulated at a center-of-mass energy of 183 GeV and correspond to an integrated luminosity of 47.7 1/pb. Production of single scalar and vector leptoquarks was searched for. Limits at 95% confidence level were derived on the masses (ranging from to for electromagnetic type couplings) and couplings of the leptoquark states.A search for top-charm flavour changing neutral currents( or charge conjugate) used the semileptonic decay channel. A limit on the flavour changing cross-section via neutral currents was set at 0.55pb (95% confidence level).A search for events with one jet and at most one isolated lepton used data taken at LEP-2 by the DELPHI detector.These data were accumulated at a center-of-mass energy of 183 GeV and correspond to an integrated luminosity of 47.7 1/pb. Production of single scalar and vector leptoquarks was searched for. Limits at 95% confidence level were derived on the masses (ranging from to for electromagnetic type couplings) and couplings of the leptoquark states.A search for top-charm flavour changing neutral currents( or charge conjugate) used the semileptonic decay channel. A limit on the flavour changing cross-section via neutral currents was set at 0.55pb (95% confidence level).A search for events with one jet and at most one isolated lepton used data taken at LEP-2 by the DELPHI detector.These data were accumulated at a center-of-mass energy of 183 GeV and correspond to an integrated luminosity of 47.7 1/pb. Production of single scalar and vector leptoquarks was searched for. Limits at 95% confidence level were derived on the masses (ranging from to for electromagnetic type couplings) and couplings of the leptoquark states.A search for top-charm flavour changing neutral currents( or charge conjugate) used the semileptonic decay channel. A limit on the flavour changing cross-section via neutral currents was set at 0.55pb (95% confidence level).A search for events with one jet and at most one isolated lepton used data taken at LEP-2 by the DELPHI detector.These data were accumulated at a center-of-mass energy of 183 GeV and correspond to an integrated luminosity of 47.7 1/pb. Production of single scalar and vector leptoquarks was searched for. Limits at 95% confidence level were derived on the masses (ranging from to for electromagnetic type couplings) and couplings of the leptoquark states.A search for top-charm flavour changing neutral currents( or charge conjugate) used the semileptonic decay channel. A limit on the flavour changing cross-section via neutral currents was set at 0.55pb (95% confidence level).A search for events with one jet and at most one isolated lepton used data taken at LEP-2 by the DELPHI detector.These data were accumulated at a center-of-mass energy of 183 GeV and correspond to an integrated luminosity of 47.7 1/pb. Production of single scalar and vector leptoquarks was searched for. Limits at 95% confidence level were derived on the masses (ranging from to for electromagnetic type couplings) and couplings of the leptoquark states.A search for top-charm flavour changing neutral currents( or charge conjugate) used the semileptonic decay channel. A limit on the flavour changing cross-section via neutral currents was set at 0.55pb (95% confidence level).A search for events with one jet and at most one isolated lepton used data taken at LEP-2 by the DELPHI detector.These data were accumulated at a center-of-mass energy of 183 GeV and correspond to an integrated luminosity of 47.7 1/pb. Production of single scalar and vector leptoquarks was searched for. Limits at 95% confidence level were derived on the masses (ranging from to for electromagnetic type couplings) and couplings of the leptoquark states.A search for top-charm flavour changing neutral currents( or charge conjugate) used the semileptonic decay channel. A limit on the flavour changing cross-section via neutral currents was set at 0.55pb (95% confidence level).A search for events with one jet and at most one isolated lepton used data taken at LEP-2 by the DELPHI detector.These data were accumulated at a center-of-mass energy of 183 GeV and correspond to an integrated luminosity of 47.7 1/pb. Production of single scalar and vector leptoquarks was searched for. Limits at 95% confidence level were derived on the masses (ranging from to for electromagnetic type couplings) and couplings of the leptoquark states.A search for top-charm flavour changing neutral currents( or charge conjugate) used the semileptonic decay channel. A limit on the flavour changing cross-section via neutral currents was set at 0.55pb (95% confidence level).A search for events with one jet and at most one isolated lepton used data taken at LEP-2 by the DELPHI detector.These data were accumulated at a center-of-mass energy of 183 GeV and correspond to an integrated luminosity of 47.7 1/pb. Production of single scalar and vector leptoquarks was searched for. Limits at 95% confidence level were derived on the masses (ranging from to for electromagnetic type couplings) and couplings of the leptoquark states.A search for top-charm flavour changing neutral currents( or charge conjugate) used the semileptonic decay channel. A limit on the flavour changing cross-section via neutral currents was set at 0.55pb (95% confidence level).A search for events with one jet and at most one isolated lepton used data taken at LEP-2 by the DELPHI detector.These data were accumulated at a center-of-mass energy of 183 GeV and correspond to an integrated luminosity of 47.7 1/pb. Production of single scalar and vector leptoquarks was searched for. Limits at 95% confidence level were derived on the masses (ranging from to for electromagnetic type couplings) and couplings of the leptoquark states.A search for top-charm flavour changing neutral currents( or charge conjugate) used the semileptonic decay channel. A limit on the flavour changing cross-section via neutral currents was set at 0.55pb (95% confidence level).A search for events with one jet and at most one isolated lepton used data taken at LEP-2 by the DELPHI detector.These data were accumulated at a center-of-mass energy of 183 GeV and correspond to an integrated luminosity of 47.7 1/pb. Production of single scalar and vector leptoquarks was searched for. Limits at 95% confidence level were derived on the masses (ranging from to for electromagnetic type couplings) and couplings of the leptoquark states.A search for top-charm flavour changing neutral currents( or charge conjugate) used the semileptonic decay channel. A limit on the flavour changing cross-section via neutral currents was set at 0.55pb (95% confidence level).A search for events with one jet and at most one isolated lepton used data taken at LEP-2 by the DELPHI detector.These data were accumulated at a center-of-mass energy of 183 GeV and correspond to an integrated luminosity of 47.7 1/pb. Production of single scalar and vector leptoquarks was searched for. Limits at 95% confidence level were derived on the masses (ranging from to for electromagnetic type couplings) and couplings of the leptoquark states.A search for top-charm flavour changing neutral currents( or charge conjugate) used the semileptonic decay channel. A limit on the flavour changing cross-section via neutral currents was set at 0.55pb (95% confidence level).A search for events with one jet and at most one isolated lepton used data taken at LEP-2 by the DELPHI detector. These data were accumulated at a center-of-mass energy of 183 GeV and correspond to an integrated luminosity of 47.7 pb −1 . Production of single scalar and vector leptoquarks was searched for. Limits at 95% confidence level were derived on the masses (ranging from 134 GeV/c 2 to 171 GeV/c 2 for electromagnetic type couplings) and couplings of the leptoquark states. A search for top-charm flavour changing neutral currents ( e + e − → t ̄ c or charge conjugate) used the semileptonic decay channel. A limit on the flavour changing cross-section via neutral currents was set at 0.55pb (95% confidence level)
A MEASUREMENT OF B-MESON PRODUCTION AND LIFETIME USING DL- EVENTS IN Z(0) DECAYS
No full textA study of B meson decays into D l- X final states is presented. In these events, neutral and charged D mesons originate predominantly from B+ and B0 decays, respectively. The dilution of this correlation due to D** production has been taken into account. From 263700 hadronic Z0 decays collected in 1991 with the DELPHI detector at the LEP collider, 92 D0 --> K- pi+, 35 D+ --> K- pi+ pi+ and 61 D*+ --> D0 pi+ followed by D0 --> K- pi+ or D0 --> K- pi+ pi+ pi-, are found with an associated lepton of the same charge as the kaon. From the D0 l- and D*+ l-, the probability f(d) that a b quark hadronizes into a B- (or B0BAR),meson is found to be 0.44 +/-0.08 +/-0.09, corresponding to a total (B(s) + LAMBDA(b)) hadronization fraction of 0.12(-0.12)+0.24 .By reconstructing the energy of each B meson, the b quark fragmentation is directly measured for the first time. The mean value of the B meson energy fraction is: [X(E)(B)] = 0.695+/-0.015(stat.)+/-0.029(syst.) Reconstructing D-lepton vertices, the following B life-times are measured: tau(B) = 1.27(-0.18)+0.22(stat.)+/-0.15(syst.) ps, where bBAR --> D0 l- X, tau(B) = 1.18(-0.27)+0.39(stat.)+/-0.15(syst.) ps, where BBAR --> D+ l- X, T(B) = 1.19(-0.19)+0.25(stat.)+/-0.15(syst.) ps where BBAR --> D*+ l- X, and an average tau(B) = 1.23(-0.13)+0.14(stat.)+/-0.15(syst.) ps is found. Allowing for decays into D** l- vBAR, the B+ and B0 lifetimes are: tau(B+)= 1.30(0.29)+0.33(stat.)+/-0.15(syst. exp.) +/-0.05(syst. D**) ps, tau(B0)= 1.17(-0.23)+0.29(stat.)+/-0.15(syst. exp.) +/-0.05 (syst. D**) ps, tau(B+)/tau(B0) = 1.11(0.39)+0.51(stat.)+/-0.05(syst. exp.) +/-0.10(syst. D**) ps
- …
