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Träfflista för sökning "L773:0170 9739 OR L773:1431 5858 "

Sökning: L773:0170 9739 OR L773:1431 5858

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1.
  • Abreu, P., et al. (författare)
  • Measurement of the GAMMA(B-B-OVER-BAR)/GAMMA(HAD) branching ratio of thez by double hemisphere tagging
  • 1995
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - 0170-9739 .- 1431-5858. ; 65:4, s. 555-568
  • Tidskriftsartikel (refereegranskat)abstract
    • Two measurements of Γbbˉ/Γhad are presented. Both measurements use 250000Z decays taken with the DELPHI detector in 1991 and rely mainly on the precision of the microvertex detector. One tagging method is as simple as possible so that background rates can be reliably predicted by simulation. The other one uses a more involved tagging technique and reduces the dependence on simulation as much as possible. Combining both results, Γbbˉ/Γhad is found to be 0.2209±0.0041(stat.)±0.0042(syst.)±0.0018 Γccˉ .
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2.
  • Adiels, L., et al. (författare)
  • Experimental determination of the branching ratios {Mathematical expression}, and 2γ at rest
  • 1987
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - : Springer. - 0170-9739 .- 1431-5858. ; 35:1, s. 15-19
  • Tidskriftsartikel (refereegranskat)abstract
    • The branching ratios of {Mathematical expression} annihilations into the neutral final states 2π 0, π 0γ, and 2γ are measured by stopping antiprotons in liquid hydrogen. They are {Mathematical expression}, {Mathematical expression}, and B γγ<1.7×10 -6 (95% c.l.).
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3.
  • Adiels, L., et al. (författare)
  • Experimental study of the inclusive η-spectrum from p {Mathematical expression} annihilations at rest in liquid hydrogen
  • 1989
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - : Springer. - 0170-9739 .- 1431-5858. ; 42:1, s. 49-58
  • Tidskriftsartikel (refereegranskat)abstract
    • The inclusive η-momentum spectrum from {Mathematical expression} annihilations at rest in liquid hydrogen was measured at LEAR. Branching ratios were obtained for {Mathematical expression}, and ηη(8.1±3.1)×10 -5. An upper limit for {Mathematical expression} of 1.8×10 -4 at 95% CL was found. The ratio of the branching ratios is BR(ηρ{variant})/BR(ηω)=0.51 -0.06 +0.20. For the ratio of branching ratios into two pseudoscalar mesons, we have BR(ηπ 0)/BR(π 0π 0)=0.65±0.14, BR(ηη)/BR(π 0π 0), BR(ηη ′)/BR(π 0π 0) at 95% CL, and BR(ηη)/BR(ηπ 0). © 1989 Springer-Verlag.
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4.
  • Adiels, Lars, et al. (författare)
  • Experimental study of the inclusive η-spectrum from proton-antiproton annihilations at rest in liquid hydrogen
  • 1989
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - 0170-9739 .- 1431-5858. ; 42, s. 49-58
  • Tidskriftsartikel (refereegranskat)abstract
    • The inclusive η-momentum spectrum from Mathematical expression annihilations at rest in liquid hydrogen was measured at LEAR. Branching ratios were obtained for Mathematical expression, and ηη(8.1±3.1)×10-5. An upper limit for Mathematical expression of 1.8×10-4 at 95% CL was found. The ratio of the branching ratios is BR(ηρvariant)/BR(ηω)=0.51-0.06+0.20. For the ratio of branching ratios into two pseudoscalar mesons, we have BR(ηπ0)/BR(Ï€0Ï€0)=0.65±0.14, BR(ηη)/BR(Ï€0Ï€0), BR(ηη′)/BR(Ï€0Ï€0) at 95% CL, and BR(ηη)/BR(ηπ0). © 1989 Springer-Verlag.
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5.
  • Amaudruz, P, et al. (författare)
  • Precision measurement of structure function ratios for 6Li, 12C and 40Ca
  • 1992
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - : Springer. - 0170-9739 .- 1431-5858. ; 53:1, s. 73-77
  • Tidskriftsartikel (refereegranskat)abstract
    • The structure function ratios F2C/F2Li, F2Ca/F2Li and F2Ca/F2C were measured in deep inelastic muon-nucleus scattering at an incident muon energy of 90 GeV, covering the kinematic range 0.0085 < x < 0.6 and 0.8 < Q2 < 17 GeV2. The sensitivity of the nuclear structure functions to the size and mean density of the target nucleus is discussed.
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6.
  • Amaudruz, P, et al. (författare)
  • Precision measurement of the structure function ratios F2He/F2D, F2C/F2D and F2Ca/F2D
  • 1991
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - : Springer. - 0170-9739 .- 1431-5858. ; 51:3, s. 387-393
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the structure function ratios F2He/F2D, F2C/F2D and F2Ca/F2D measured in deep inelastic muon-nucleus scattering at an incident muon momentum of 200 GeV. The kinematic range 0.0035 < x < 0.65 and 0.5 < Q2 < 90 GeV2 is covered. At low x the three ratios are significantly smaller than unity and the size of the depletion grows with decreasing x and increasing mass number A. At intermediate x the ratios show an enhancement of about 2% above unity for C/D and Ca/D, possibly less for He/D. There are indications of some Q2 dependence in the Ca/D data. The integrals of the structure function differences F2A-F2D are discussed.
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7.
  • Amaudruz, P, et al. (författare)
  • Transverse momentum distributions for exclusive ρ0 muoproduction
  • 1992
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - : Springer. - 0170-9739 .- 1431-5858. ; 54:2, s. 239-245
  • Tidskriftsartikel (refereegranskat)abstract
    • We have studied transverse momentum distributions for exclusive rho(0) muoproduction on protons and heavier nuclei at 2 < Q2 < 25 GeV2. The Q2 dependence of the slopes of the p(t)2 and t' distributions is discussed. The influence of the non-exclusive background is investigated. The p(t)2-slope for exclusive events is 4.3 +/- 0.6 +/- 0.7 GeV-2 at large Q2. The p(t)2 spectra are much softer than inclusive p(t)2 spectra of leading hadrons produced in deep inelastic scattering.
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8.
  • Andersson, Bo, et al. (författare)
  • Structure Functions and general final state properties in the linked dipole chain model
  • 1996
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - : Springer Science and Business Media LLC. - 0170-9739 .- 1431-5858. ; 71:4, s. 613-624
  • Tidskriftsartikel (refereegranskat)abstract
    • We have in an earlier paper, [1], presented a generalization, the Linked Dipole Chain Model LDC, of the model developed by Ciafaloni-Catani-Fiorani-Marchesini, [2], to decribe the structure functions and the states in Deep Inelastic Scattering events. In this paper we would like to present an investigation of a set of general features of the LDC Model, viz the behaviour of the structure functions (we will show how the result interpolates in a precise way in between the well-known DGLAP and BFKL approaches), the average bremsstrahlung emission in the states and finally a partitioning of the structure functions into three different channels: the ''ordinary'' parton-probe events, where all bremsstrahlung emissions are below the probe Q(2), the boson-gluon fusion events where the last splitting of the par ton chains contain transverse momentum above Q(2), and the resolved Rutherford scattering events between the probe and the hadron (where the largest transverse momentum occur somewhere along the emission lines away from the ends).
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9.
  • Ashman, J, et al. (författare)
  • A measurement of the ratio of the nucleon structure function in copper and deuterium
  • 1993
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - : Springer. - 0170-9739 .- 1431-5858. ; 57:2, s. 211-218
  • Tidskriftsartikel (refereegranskat)abstract
    • Results are presented on the ratios of the nucleon structure function in copper to deuterium from two separate experiments. The data confirm that the nucleon structure function, F2, is different for bound nucleons than for the quasi-free ones in the deuteron. The redistribution in the fraction of the nucleon's momentum carried by quarks is investigated and it is found that the data are compatible with no integral loss of quark momenta due to nuclear effects.
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10.
  • Ashman, J, et al. (författare)
  • Exclusive ρ0 and Φ production in deep inelastic muon scattering
  • 1988
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - New York, USA : Springer. - 0170-9739 .- 1431-5858. ; 39:2, s. 169-175
  • Tidskriftsartikel (refereegranskat)abstract
    • Data are presented on exclusive ρ0 and φ{symbol} production in deep inelastic muon scattering from a target consisting mainly of nitrogen. The ratio of the total cross sections for ρ0 and φ{symbol} production is found to be 9:(1.6±0.4) at 〈Q2〉=7.5 GeV2, consistent with the SU(3) prediction of 9:2. The t dependence for exclusive ρ0 production is found to become shallover as Q2 increases and, for large Q2, the t dependence is typical of that for a hard scattering process. Furthermore, the ratio of the cross sections for coherent: incoherent production from nitrogen is found to decrease rapidly with Q2. Such behaviour indicates that even for exclusive vector meson production the virtual photon behaves predominantly as an electromagnetic probe.
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11.
  • Ashman, J, et al. (författare)
  • Forward produced hadrons in μp and μd scattering and investigation of the charge structure of the nucleon
  • 1991
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - : Springer. - 0170-9739 .- 1431-5858. ; 52:3, s. 361-387
  • Tidskriftsartikel (refereegranskat)abstract
    • Final data measured with the EMC forward spectrometer are presented on the production of forward charged hadrons in mu-p and mu-d scattering at incident beam energies between 100 and 280 GeV. The large statistic of 373000 events allows a study of the semi-inclusive hadron production as a function of z, p(T)2 and in small Q2, x(Bj) and W bins. Charge multiplicity ratios and differences as a function of z and x(Bj) are given for p, d and n-targets. From the differences of charge multiplicities the ratio of the valence quark distributions of the proton d-upsilon(x)/u-upsilon(x) is determined for the first time in charged lepton scattering. The Gronau et al. sum rule is tested, the measured sum being 0.31 +/- 0.06 stat. +/- 0.05 syst., compared with the theoretical expectation of 2/7 almost-equal-to 0.286. The measured sum corresponds to an absolute value of the ratio of the d and u quark charge of 0.44 +/- 0.10 stat. +/- 0.08 syst.
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12.
  • Ashman, J, et al. (författare)
  • Muoproduction of J/ψ and the gluon distribution of the nucleon
  • 1992
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - : Springer. - 0170-9739 .- 1431-5858. ; 56:1, s. 21-28
  • Tidskriftsartikel (refereegranskat)abstract
    • Measurements are presented of the inclusive distributions of the J/psi meson produced by muons of energy 200 GeV from an ammonia target. The gluon distribution of the nucleon has been derived from the data in the range 0.04 < x < 0.36 using a technique based on the colour singlet model. An arbitrary normalisation factor is required to obtain a reasonable integral of the gluon distribution. Some comments are made on the use of J/psi production by virtual photons to extract the gluon distribution at HERA.
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13.
  • Fredriksson, Sverker, et al. (författare)
  • A new diquark model for deep inelastic structure functions
  • 1982
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - 0170-9739 .- 1431-5858. ; 14:1, s. 35-39
  • Tidskriftsartikel (refereegranskat)abstract
    • The bulk of data from deep inelasticep, eD, μp, μN, νp and νN scattering is fitted with a new diquark model of nucleons. The proton is found to be mostly in au(ud) 0 state, where the (ud)0 diquark has spin and isospin zero. There is hence no trace ofSU(6) symmetry among diquarks in nucleons.
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14.
  • Fredriksson, Sverker, et al. (författare)
  • A new indication of diquarks in baryons
  • 1982
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - 0170-9739 .- 1431-5858. ; 14:1, s. 41-46
  • Tidskriftsartikel (refereegranskat)abstract
    • In data from 100 GeV/c p d, 200 GeV/cpd and 200 GeV/cπ - d collisions there is evidence that the probability for a double-collisiondecreases slowly with increasing number of hadrons produced in the first projectile-nucleon collision. We argue that the presence of diquarks in baryons is the only plausible explanation of such an effect.
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15.
  • Fredriksson, Sverker, et al. (författare)
  • A potential diquark in the proton
  • 1997
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - : Springer Science and Business Media LLC. - 0170-9739 .- 1431-5858. ; 75:1, s. 107-111
  • Tidskriftsartikel (refereegranskat)abstract
    • A non-relativistic, QCD-based, potential quark model for the proton and the neutron inevitably predicts a spin-0 diquark structure with an rms radius of the order of 0.35rfm or smaller. We prove this by solving the (S wave) hamiltonian by De Rújula et al. with variational methods. It is essential to include all quark interactions and to use realistic test wave-functions. The protondelta mass difference, the magnetic moments and the nucleon charge radii can be reproduced only with wave functions that contain a mixture of quark-diquark and three-quark states. Approaches with just a quark-diquark component give incorrect magnetic moments, while those without diquarks lead to a too low proton-delta mass difference.
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16.
  • Fredriksson, Sverker, et al. (författare)
  • Probing spin-1 diquarks in deep inelastic structure functions
  • 1983
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - 0170-9739 .- 1431-5858. ; 19:1, s. 53-55
  • Tidskriftsartikel (refereegranskat)abstract
    • Within the scope of a new diquark model for deep inelastic structure functions presented by us recently we use the existing data onF 1 ep (x,Q2) to learn about the admixture of spin-1 diquarks in nucleons. It turns out that they are so rare, heavy and extended compared to spin-0 diquarks that they are presumably accidental and not dynamical. Their number and form factors can be understood qualitatively within this picture. Still, the spin-1 diquarks give interesting structures in data and, together with quarks and spin-0 diquarks, carry enough momentum to account for the full nucleon energy. A gluon component is hence not needed in the nucleon!
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17.
  • Fredriksson, Sverker, et al. (författare)
  • Probing the space-time structure of multiparticle production processes
  • 1981
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - 0170-9739 .- 1431-5858. ; 10:2, s. 185-187
  • Tidskriftsartikel (refereegranskat)abstract
    • It is shown that the models for highenergy multiparticle production in which the notion of a hadronicformation time plays a central role are in disagreement with recently published compilations of the rescatter probabilities in 100 GeV/c p d and 200 GeV/c p d collisions.
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18.
  • Gustafson, Gösta, et al. (författare)
  • Baryon production in the string fragmentation picture
  • 1997
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - : Springer Science and Business Media LLC. - 0170-9739 .- 1431-5858. ; 75:1, s. 41-49
  • Tidskriftsartikel (refereegranskat)abstract
    • An improved version of the “pop-corn” model for baryon production in quark and gluon jets is presented. With a reduced number of parameters the model reproduces well both production rates for different baryon species and baryon momentum distributions. Predictions are presented for a set of baryon-antibaryon correlations.
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19.
  • Houra-Yaou, Ladonne, et al. (författare)
  • Production of meson pairs, involving tensor and pseudotensor mesons, in photon-photon collisions
  • 1997
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - : Springer Science and Business Media LLC. - 0170-9739 .- 1431-5858. ; 76:3, s. 537-547
  • Tidskriftsartikel (refereegranskat)abstract
    • Starting from a bound-state model of weakly bound quarks for (q [`(q)]) mesons, we derive a formalism for computing the production or decay of such mesons, whatever the value of their internal orbital angular momentum L. That approach appears as a natural generalization of the Brodsky-Lepage formalism (valid only for L=0) that has been widely used in recent years for the computation of exclusive processes in perturbative QCD . We here apply it to the production, in photon-photon collisions, of: i) tensor-meson pairs; ii) pseudotensor-meson pairs; iii) hybrid pairs made of a pion and a pseudotensor meson. The numerical results we obtain allow for some hope of experimentally identifying such pairs, in the charged channels, at high-energy e+e- colliders of the next generation, provided integrated luminosities as high as » 1040 cm-2 can be reached.
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20.
  • Häkkinen, Jari (författare)
  • bbˉ -fragmentation and Bpπ correlations
  • 1997
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - : Springer Science and Business Media LLC. - 0170-9739 .- 1431-5858. ; 75:1, s. 35-40
  • Tidskriftsartikel (refereegranskat)abstract
    • We show that experimental data are in very good agreement with predictions from the string fragmentation model by Bowler and Morris. We present a physical interpretation and discuss the relation to results obtained from Perturbative QCD and Local Hadron Parton Duality (LPHD). We also present implications for Bp correlations and the possibility to use these as a tag to study CP violation in B decays.
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21.
  • Khoze, Valery A., et al. (författare)
  • QED interconnection effects on $W$ momentum distributions at LEP-2
  • 1996
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - : Springer Science and Business Media LLC. - 0170-9739 .- 1431-5858. ; 70:4, s. 625-636
  • Tidskriftsartikel (refereegranskat)abstract
    • The process ${⤪ e}^{+}{⤪ e}^{-}⌝ghtarrow {⤪ W}^{+}{⤪ W}^{-}⌝ghtarrow {⤪ f}_{1}{⩈erline {⤪ f}}_{2}{⤪ f}_{3}{⩈erline {⤪ f}}_{4}$ contains charges in the initial, intermediate and final stages. This gives a rich selection of possible QED interconnection effects. Coulomb interaction is the simplest of these, and can thus be used to explore consequences. We study a number of experimental observables, with emphasis on those related to the W momentum distribution. Second-order Coulomb effects are shown to be practically negligible. The limited LEP 2 statistics will not allow detailed tests, so any theory uncertainty will be reflected in the systematic error on the W mass. Currently the uncertainty from this source may be as high as 20 MeV.
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22.
  • Schuler, Gerhard A., et al. (författare)
  • A scenario for high-energy γγ interactions
  • 1997
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - : Springer Science and Business Media LLC. - 0170-9739 .- 1431-5858. ; 73:4, s. 677-688
  • Tidskriftsartikel (refereegranskat)abstract
    • A real photon has a complicated nature, whereby it may remain unresolved or fluctuate into a vector meson or a perturbative qq̄ pair. In γγ events, this gives three by three combinations of the nature of the two incoming photons, and thus six distinct event classes. The properties of these classes are partly constrained by the choices already made in our related γp model. It is therefore possible to predict the energy-dependence of the cross section for each of the six components separately. The total cross section gives support to the idea that a simple factorized ansatz with a pomeron and a reggeon term can be a good approximation. Event properties undergo a stepwise evolution from pp to γp to γγ events, with larger charged multiplicity, more transverse energy flow and a higher jet rate in the latter process.
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23.
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24.
  • Abreu, P, et al. (författare)
  • A precise measurement of the B-d(0) meson lifetime using a new technique
  • 1997
  • Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 74:1, s. 19-32
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • From data recorded by DELPHI between 1991 and 1994, which corresponds to 3.2 million hadronic Z(0) decays, a measurement of the <(B-d(0))over bar> meson lifetime, based on the inclusive reconstruction of 3520 +/- 150 semileptonic decays of the type <(B-d(
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25.
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26.
  • Abreu, P, et al. (författare)
  • Determination of the average lifetime of b-baryons
  • 1996
  • Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 71:2, s. 199-210
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • The average lifetime of b-baryons has been studied using 3 x 10(6) hadronic Z(0) decays collected by the DELPHI detector at LEP. Three methods have been used, based on the measurement of different observables: the proper decay time distribution of 206 ver
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27.
  • Abreu, P, et al. (författare)
  • Determination of vertical bar V-cb vertical bar from the semileptonic decay B-0->D*(-)l(+)nu
  • 1996
  • Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 71:4, s. 539-553
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Semileptonic decays B --> D*(-)l(+)nu X were selected from a sample of 3.1 million hadronic Z decays collected by the DELPHI detector at LEP. A topological search for semileptonic B decays to resonant and non-resonant D*(-)pi(+) states was performed and t
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28.
  • Abreu, P, et al. (författare)
  • Energy dependence of the differences between the quark and gluon jet fragmentation
  • 1996
  • Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 70:2, s. 179-195
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Three jet events arising from decays of the Z beson, collected by the DELPHI detector, were used to measure differences in quark and gluon fragmentation. Gluon jets were anti-tagged by identifying b quark jets. Unbiased quark jets came from events with tw
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29.
  • Abreu, P, et al. (författare)
  • First study of the interference between initial and final state radiation at the Z resonance
  • 1996
  • Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 72:1, s. 31-38
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • The interference between initial and final state radiation in the process e(+)e(-) --> mu(+)mu(-) at root s approximate to M(Z) has been studied by measuring the forward-backward asymmetry as a function of the acoplanarity angle between the final state mu
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30.
  • Abreu, P, et al. (författare)
  • Mean lifetime of the B-s(0) meson
  • 1996
  • Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 71:1, s. 11-30
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • This paper presents an update of the measurement of the mean lifetime of the B-s(0) meson. Combining D-s - l, D-s - h, phi - l and inclusive D-s final states from the 3.2 million hadronic Z decays collected by DELPHI between 1991 and 1994, the B-s(0) mean
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31.
  • Abreu, P, et al. (författare)
  • Measurement of B-d(0)-(B-d(0))over-bar oscillations
  • 1997
  • Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 76:4, s. 579-598
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • B-d(0) meson oscillations are measured in hadronic Z(0) decays using the charge of a lepton or the mean charge of an event hemisphere to sign the presence of a b or a (b) over bar quark when it is produced, and using the charge of a lepton emitted at larg
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32.
  • Abreu, P, et al. (författare)
  • Measurement of inclusive K*(0)(892), phi(1020) and K-2*(0)(1430) production in hadronic Z decays
  • 1996
  • Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 73:1, s. 61-72
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • The inclusive production of the neutral vector mesons K-*0(892) and phi(1020), and of the tensor meson K-2(*0)(1430), in hadronic decays of the Z has been mea sured by the DELPHI detector at LEP. The average production rates per hadronic Z decay have been
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33.
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34.
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35.
  • Abreu, P, et al. (författare)
  • Search for neutral heavy leptons produced in Z decays
  • 1997
  • Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 74:1, s. 57-71
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Weak isosinglet Neutral Heavy Leptons (nu(m)) have been searched for using data collected by the DELPHI detector corresponding to 3.3 x 10(6) hadronic Z(0) decays at LEP1. Four separate searches have been performed, for short-lived nu(m) production giving
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36.
  • Abreu, P, et al. (författare)
  • Search for new phenomena using single photon events at LEP1
  • 1997
  • Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 74:4, s. 577-586
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Data are presented on the reaction e(+)e(-) --> gamma + no other detected particle at centre-of-mass energies of 89.48, 91.26 and 93.08 GeV. The cross-section for this reaction is related directly to the number of light neutrino generations which couple t
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37.
  • Abreu, P, et al. (författare)
  • Tuning and test of fragmentation models based on identified particles and precision event shape data
  • 1996
  • Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 73:1, s. 11-59
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Event shape and charged particle inclusive distributions are measured using 750000 decays of the Z to hadrons from the DELPHI detector at LEP, These precise data allow a decisive confrontation with models of the hadronization process, Improved tunings of
  •  
38.
  • Adam, W, et al. (författare)
  • Measurement of inclusive pi(0) production in hadronic Z(0) decays
  • 1996
  • Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 69:4, s. 561-573
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • An analysis is presented of inclusive pi(0) production in Z(0) decays measured with the DELPHI detector, At low energies, pi(0) decays are reconstructed by using pairs of converted photons and combinations of converted photons and photons reconstructed in
  •  
39.
  • Adam, W, et al. (författare)
  • Production of Sigma(0) and Omega(-) in Z decays
  • 1996
  • Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 70:3, s. 371-381
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Reconstructed ii baryon decays and photon conversions in DELPHI are used to measure the Sigma(0) production rate from hadronic Z(0) decays at LEP. The number of Sigma(0) decays per hadronic Z decay is found to be: > = 0.07
  •  
40.
  • Adam, W, et al. (författare)
  • Search for pair production of heavy objects in 4-jet events at root s=130-136 GeV
  • 1996
  • Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 73:1, s. 1-9
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Results are presented of a search for pair production of heavy objects decaying into four hadronic jets, as expected for example from associated or pair production of MSSM Higgs bosons, hA or H+H-, using a data sample of 5.9 pb(-1) of e(+)e(-) collisions
  •  
41.
  • Adam, W, et al. (författare)
  • Study of rare b decays with the DELPHI detector at LEP
  • 1996
  • Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 72:2, s. 207-220
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Rare decays of beauty particles were studied in several charmless modes using the data collected with the DELPHI detector at LEP from 1991 to 1994. These decays are mediated by both tree level b-->u and one-loop penguin b-->s, d transitions. Evidence for
  •  
42.
  • Adiels, L., et al. (författare)
  • Experimental determination of the branching ratios proton-antiproton -> 2pi0, pi0γ and γγ at rest
  • 1987
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - 0170-9739. ; 35:1, s. 15-19
  • Tidskriftsartikel (refereegranskat)abstract
    • The branching ratios of Mathematical expression annihilations into the neutral final states 2Ï€0, Ï€0γ, and 2γ are measured by stopping antiprotons in liquid hydrogen. They are Mathematical expression, Mathematical expression, and Bγγ<1.7×10-6 (95% c.l.). © 1987 Springer-Verlag.
  •  
43.
  • Adiels, L., et al. (författare)
  • Pi0 and eta spectra from proton-antiproton annihilations at rest
  • 1984
  • Ingår i: Zeitschrift für Physik. C, Particles and fields. - 0170-9739. ; 21:4, s. 315-319
  • Tidskriftsartikel (refereegranskat)abstract
    • The low-energy part of the Ï€0 spectrum associated with Mathematical expression annihilation at rest was measured in order to search for bound baryonium-like states. The upper limit for reaching such states via the emission of monochromatic Ï€0’s was found to be 8% per annihilation in the mass region of 1650 MeV. The low-energy part of the η spectrum from Mathematical expression annihilations at rest was also observed.
  •  
44.
  • Andersson, Bo, et al. (författare)
  • A general model for jet fragmentation
  • 1983
  • Ingår i: European Physical Journal C. - 0170-9739. ; 20:4, s. 317-329
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a general condition on quark fragmentation which gives a hadron distribution satisfying Lorentz invariance and causality. The hadronization can be described as an iterative cascade process, symmetric with respect to iteration from the quark and the antiquark ends. The possible particle distributions are strongly restricted, with few free parameters related to the total multiplicity and corelations in rapidity. These parameters can be given an appealing interpretation in terms of the expected area and perimeter dependence of Wilson loop integrals.
  •  
45.
  • Andersson, B., et al. (författare)
  • A semiclassical model for quark jet fragmentation
  • 1979
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - 0170-9739. ; 1:1, s. 105-116
  • Tidskriftsartikel (refereegranskat)abstract
    • A semiclassical model is presented for the way the energy of a fast quark is transformed into observable hadrons. It reproduces the features of 1+1 dimensional QED (the Schwinger model) concerning a flat rapidity distribution in the central region. It also reproduces results from phenomenological considerations, which, based upon scaling, predict that meson formation in the fragmentation region can be described by an iterative scheme, implying a set of coupled integral equations. In particular the model predicts that the probability to find a meson containing the leading quark is independent of the Feynman scaling variable z. The iterative structure corresponds to a Brownian motion with relevance both to the confinement problems and to the distribution of mass in the quark jet.
  •  
46.
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47.
  •  
48.
  • Andersson, Bo, et al. (författare)
  • Coherence Effects in Deep Inelastic Scattering
  • 1989
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - 0170-9739. ; 43:4, s. 625-632
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a framework for deep inelastic scattering, with bound state properties in accordance with a QCD force field acting like a vortex line in a colour superconducting vacuum, which implies some simple coherence effects. Within this scheme one may describe the results of present energies very well, but one obtains an appreciable depletion of gluon radiation in the HERA energy regime.
  •  
49.
  •  
50.
  • Andersson, Bo, et al. (författare)
  • ON HIGH-ENERGY LEPTOPRODUCTION
  • 1981
  • Ingår i: Zeitschrift für Physik C Particles and Fields. - 0170-9739. ; C9, s. 233-233
  • Tidskriftsartikel (refereegranskat)
  •  
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