SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Ekelof T.) "

Sökning: WFRF:(Ekelof T.)

  • Resultat 1-10 av 87
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Abdallah, J., et al. (författare)
  • A determination of the centre-of-mass energy at LEP2 using radiative two-fermion events
  • 2006
  • Ingår i: European Physical Journal C. Particles and Fields. - Springer. - 1434-6044. ; 46:2, s. 295-305
  • Tidskriftsartikel (refereegranskat)abstract
    • Using e(+)e(-) -> mu(+)mu(-)(gamma) and e(+)e(-) -> q (q) over bar(gamma) events radiative to the Z pole, DELPHI has determined the centre-of-mass energy, root s, using energy and momentum constraint methods. The results are expressed as deviations from the nominal LEP centre-of-mass energy, measured using other techniques. The results are found to be compatible with the LEP Energy Working Group estimates for a combination of the 1997 to 2000 data sets.
  •  
2.
  • Abdallah, J., et al. (författare)
  • Study of double-tagged gamma gamma events at LEPII
  • 2006
  • Ingår i: European Physical Journal C. Particles and Fields. - Springer. - 1434-6044. ; 46:3, s. 559-568
  • Tidskriftsartikel (refereegranskat)abstract
    • Double-tagged interactions of photons with virtualities Q(2) between 10 GeV2 and 200 GeV2 are studied with the data collected by DELPHI at LEPII from 1998 to 2000, corresponding to an integrated luminosity of 550 pb(-1). The gamma*gamma* -> mu(+)mu(-) data agree with QED predictions. The cross-section of the reaction gamma*gamma* -> hadrons is measured and compared to the LO and NLO BFKL calculations.
  •  
3.
  • Abdallah, J, et al. (författare)
  • Study of inclusive J/psi production in two-photon collisions at LEP II with the DELPHI detector
  • 2003
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - Elsevier. - 0370-2693. ; 565:1-4, s. 76-86
  • Tidskriftsartikel (refereegranskat)abstract
    • Inclusive J/psi production in photon-photon collisions has been observed at LEP II beam energies. A clear signal from the reaction gammagamma --> J/psi + X is seen. The number of observed N(J/psi --> mu(+)mu(-)) events is 36+/-7 for an integrated luminosity of 617 pb(-1), yielding a cross-section of sigma(J/psi + X) = 45+/-9(stat) +/- 17(syst) pb. Based on a study of the event shapes of different types of gammagamma processes in the PYTHIA program, we conclude that (74+/-22) % of the observed J/psi events are due to 'resolved' photons, the dominant contribution of which is most probably due to the gluon content of the photon. (C) 2003 Published by Elsevier B.V.
  •  
4.
  • Abdallah, J, et al. (författare)
  • A precise measurement of the B+, B-0 and mean b-hadron lifetime with the DELPHI detector at LEP I
  • 2004
  • Ingår i: European Physical Journal C. Particles and Fields. - Springer. - 1434-6044. ; 33:3, s. 307-324
  • Tidskriftsartikel (refereegranskat)abstract
    • Final results from the DELPHI Collaboration on the lifetime of B+ and B-0 mesons and the mean b-hadron lifetime, are presented using the data collected at the Z(0) peak in 1994 and 1995. Elaborate, inclusive, secondary vertexing methods have been employed to ensure a b-hadron reconstruction with good efficiency. To separate samples of B+ and B-0 mesons, high performance neural network techniques are used that achieve very high purity signals. The results obtained are: tau(B+) = 1.624+/-0.014 (stat)+/-0.018 (syst) ps tau(B)0 = 1.531+/-0.021 (stat)+/-0.031 (syst) ps tau(B+)/tau(B)0 = 1.060+/-0.021 (stat)+/-0.024 (syst) and for the average b-hadron lifetime: taub/tau(B)0 = 1.570+/-0.005 (stat)+/-0.008 (syst) ps.
  •  
5.
  • Abdallah, J, et al. (författare)
  • Correlations between polarisation states of W particles in the reaction e(-)e(+)-> W-W+ at LEP2 energies 189-209 GeV
  • 2009
  • Ingår i: European Physical Journal C. Particles and Fields. - Springer. - 1434-6044. ; 63:4, s. 611-623
  • Tidskriftsartikel (refereegranskat)abstract
    • In a study of the reaction e(-)e(+)-> W-W+ with the DELPHI detector, the probabilities of the two W particles occurring in the joint polarisation states transverse-transverse (T T), longitudinal-transverse plus transverse-longitudinal (LT) and longitudinal-longitudinal (LL) have been determined using the final states WW -> lvq (q) over bar (l = e, mu). The two-particle joint polarisation probabilities, i.e. the spin density matrix elements rho T T, rho LT, rho LL, are measured as functions of the W- production angle, theta(W-), at an average reaction energy of 198.2 GeV. Averaged over all cos.W-, the following joint probabilities are obtained: (rho) over barT T = (67 +/- 8)%, (rho) over barL T = (30 +/- 8)%, (rho) over barL T = (3 +/- 7)%. These results are in agreement with the Standard Model predictions of 63.0%, 28.9% and 8.1%, respectively. The related polarisation cross-sections sigma(TT), sigma(LT) and sigma(LL) are also presented.
  •  
6.
  • Abdallah, J., et al. (författare)
  • Determination of the b quark mass at the M-Z scale with the DELPHI detector at LEP
  • 2006
  • Ingår i: European Physical Journal C. Particles and Fields. - Springer. - 1434-6044. ; 46:3, s. 569-583
  • Tidskriftsartikel (refereegranskat)abstract
    • An experimental study of the normalized three-jet rate of b quark events with respect to light quarks events (light = l equivalent to u, d, s) has been performed using the CAMBRIDGE and DURHAM jet algorithms. The data used were collected by the DELPHI experiment at LEP on the Z peak from 1994 to 2000. The results are found to agree with theoretical predictions treating mass corrections at next-to-leading order. Measurements of the b quark mass have also been performed for both the b pole mass: M-b and the b running mass: m(b)(M-Z). Data are found to be better described when using the running mass. The measurement yields: m(b)(M-Z) = 2.85 +/- 0.18(stat) +/- 0.13(exp) +/- 0.19(had) +/- 0.12(theo) GeV/c(2). for the CAMBRIDGE algorithm. This result is the most precise measurement of the b mass derived from a high energy process. When compared to other b mass determinations by experiments at lower energy scales, this value agrees with the prediction of quantum chromodynamics for the energy evolution of the running mass. The mass measurement is equivalent to a test of the flavour independence of the strong coupling constant with an accuracy of 7 parts per thousand.
  •  
7.
  • Abdallah, J, et al. (författare)
  • Inclusive single-particle production in two-photon collisions at LEP II with the DELPHI detector
  • 2009
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - Elsevier. - 0370-2693. ; 678:5, s. 444-449
  • Tidskriftsartikel (refereegranskat)abstract
    • A study of the inclusive charged hadron production in two-photon collisions is described. The data were collected with the DELPHI detector at LEP II. Results on the inclusive single-particle PT distribution and the differential charged hadrons d sigma/dp(T) cross-section are presented and compared to the predictions of perturbative NLO QCD calculations and to published results. (C) 2009 Elsevier B.V. All rights reserved.
  •  
8.
  • Abdallah, J, et al. (författare)
  • Rapidity-alignment and p(T) compensation of particle pairs in hadronic Z(0) decays
  • 2002
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - Elsevier. - 0370-2693. ; 533:3-4, s. 243-252
  • Tidskriftsartikel (refereegranskat)abstract
    • Observation is made of rapidity-alignment of K+K- and (p) over barp pairs which results from their asymmetric orientation in rapidity, with respect to the direction from primary quark to antiquark. The K+K- and (p) over barp data are consistent with predictions from the fragmentation string model. However, the (p) over barp data strongly disagree with the conventional implementation of the cluster model. The non-perturbative process of 'gluon splitting to diquarks' has to be incorporated into the cluster model for it to agree with the data. Local conservation of PT between particles nearby in rapidity (i.e., p(T) compensation) is analysed with respect to the thrust direction for pi(+)pi(-), K+K-, and (p) over barp pairs. In this case, the string model provides fair agreement with the data. The cluster model is incompatible with the data for all three particle pairs. The model with its central premiss of isotropically-decaying clusters predicts a p(T) correlation not seen in the data. (C) 2002 Elsevier Science B.V. All rights reserved.
  •  
9.
  • Abdallah, J, et al. (författare)
  • Search for charged Higgs bosons in e(+)e(-) collisions root s=189-202 GeV
  • 2002
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - Elsevier. - 0370-2693. ; 525:1-2, s. 17-28
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for pair-produced charged Higgs bosons was performed in the high energy data collected by the DELPHI detector at LEP II at centre-of-mass energies from 189 GeV to 202 GeV. The three different final states, taunutaunu, c (s) over bar(c) over bars and c (s) over bar taunu were considered. New methods were applied to reject wrong hadronic jet pairings and for the tau identification, where a discriminator based on tau polarisation and polar angles was used. No excess of data compared to the expected Standard Model processes was observed and the existence of a charged Higgs boson with mass lower than 71.5 GeV/c(2) is excluded at the 95% confidence level. (C) 2002 Published by Elsevier Science B.V.
  •  
10.
  • Abdallah, J, et al. (författare)
  • Study of tau-pair production in photon-photon collisions at LEP and limits on the anomalous electromagnetic moments of the tau lepton
  • 2004
  • Ingår i: European Physical Journal C. Particles and Fields. - Springer. - 1434-6044. ; 35:2, s. 159-170
  • Tidskriftsartikel (refereegranskat)abstract
    • Tau-pair production in the process e(+)e(-) --> e(+)e(-) tau(+)tau(-) was studied using data collected by the DELPHI experiment at LEP2 during the years 1997 - 2000. The corresponding integrated luminosity is 650 pb(-1). The values of the cross-section obtained are found to be in agreement with QED predictions. Limits on the anomalous magnetic and electric dipole moments of the tau lepton are deduced.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-10 av 87
 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy