Publications
708 results found
Dauncey PD, 1996, Performance of the DELPHI detector, Nuclear Instruments & Methods in Physics Research Section A- Accelerators Spectrometers Detectors and Associated Equipment, Vol: 378, Pages: 57-100, ISSN: 0168-9002
Abreu P, Adam W, Adye T, et al., 1995, Study of prompt photon production in hadronic Z<sup> 0</sup> decays, Zeitschrift für Physik C: Particles and Fields, Vol: 69, Pages: 1-13, ISSN: 0170-9739
From a sample of 1.5 million Z 0→qq decays collected by the DELPHI detector during 1991, 1992 and 1993, the production cross section for isolated final state photons is measured and is compared with the O(α, α s) matrix element calculations implemented in the EEPRAD and GNJETS Monte Carlo generators. The observed photon yield is used to derive the electroweak couplings of charge 2/3 (u-type) and charge 1/3 (d-type) quarks to the Z 0 boson. The measured values c 2/3=0.91 -0.36 +0.25 and c 1/3=1.62 -0.17 +0.24 are compatible with the Standard Model prediction, c 2/3=1.145 and c 1/3=1.477. © 1996 Springer-Verlag.
Abreu P, Adam W, Adye T, et al., 1995, A measurement of the photon structure function F<inf>2</inf><sup>γ</sup>at an average Q<sup>2</sup>of 12 GeV<sup>2</sup>/c<sup>4</sup>, Zeitschrift für Physik C: Particles and Fields, Vol: 69, Pages: 223-233, ISSN: 0170-9739
The hadronic photon structure function F 2 γ has been measured in the Q 2 range from 4 to 30 GeV 2 /c 4 and down to x values of order 0.001, using data taken with the DELPHI detector at LEP between 1991 and 1993. A comparison is made with several F 2 γ parameterizations with special emphasis on their low x behaviour. A result on the Q 2 evolution of F 2 γ is presented. © 1996 Springer-Verlag.
Adam W, Adye T, Agasi E, et al., 1995, Measurement of inclusive π<sup> 0</sup> production in hadronic Z<sup> 0</sup> decays, Zeitschrift für Physik C: Particles and Fields, Vol: 69, Pages: 561-573, ISSN: 0170-9739
An analysis is presented of inclusive π 0 production in Z 0 decays measured with the DELPHI detector. At low energies, π 0 decays are reconstructed by using pairs of converted photons and combinations of converted photons and photons reconstructed in the barrel electromagnetic calorimeter (HPC). At high energies (up to {Mathematical expression}) the excellent granularity of the HPC is exploited to search for two-photon substructures in single showers. The inclusive differential cross section is measured as a function of energy for qq and bb events. The number of π 0's per hadronic Z 0 event is N(π 0)/Z had 0 =9.2±0.2(stat)±1.0(syst) and for bb events the number of π 0's is N(π 0)/bb=10.1±0.4(stat)±1.1(syst). The ratio of the number of π 0's in bb events to hadronic Z 0 events is less affected by the systematic errors and is found to be 1.09±0.05±0.01. The measured π 0 cross sections are compared with the predictions of different parton shower models. For hadronic events, the peak position in the ξ p=ln(1/xp) distribution is ξ* p =3.90 -0.14 +0.24 . The average number of π 0's from the decay of primary B hadrons is found to be N(B→π 0 X)/B hadron=2.78±0.15(stat)±0.60(syst). © 1996 Springer-Verlag.
Abreu P, Adam W, Adye T, et al., 1995, Search for promptly produced heavy quarkonium states in hadronic Z decays, Zeitschrift für Physik C: Particles and Fields, Vol: 69, Pages: 575-583, ISSN: 0170-9739
A search has been made for direct production of heavy quarkonium states in more than 3 million hadronic Z 0 decays in the 1991-1994 DELPHI data. Prompt J/ψ, ψ(2 S) and Γ candidates have been searched for through their leptonic decay modes using criteria based on the kinematics and decay vertex positions. New upper limits are set at the 90% confidence level for Br(Z 0→(Qq)X)/Br(Z 0→ hadrons) for various strong production mechanisms of J/ψ and Γ; these range down to 0.9×10-4. The limits are set in the presence of a small excess (∼1% statistical probability of a background fluctuation) in the sum of candidates from prompt J/ψ, ψ(2 S), γ(1 S), γ(2 S) and γ(3 S) relative to the estimated background. © 1996 Springer-Verlag.
ABREU P, ADAM W, ADYE T, et al., 1995, STUDY OF PROMPT PHOTON PRODUCTION IN HADRONIC Z(0) DECAYS, ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS, Vol: 69, Pages: 1-13, ISSN: 0170-9739
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- Citations: 14
ABREU P, ADAM W, ADYE T, et al., 1995, MEASUREMENT OF DELTA(++)(1232) PRODUCTION IN HADRONIC-Z-DECAYS, PHYSICS LETTERS B, Vol: 361, Pages: 207-220, ISSN: 0370-2693
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- Citations: 18
Abreu P, Adam W, Adye T, et al., 1995, Upper limits on the branching ratios τ → μγ and τ → eγ, Physics Letters B, Vol: 359, Pages: 411-421, ISSN: 0370-2693
The DELPHI collaboration has searched for lepton flavour violating decays τ → μγ and τ → μgg using a data sample of about 70 pb-1 of integrated luminosity corresponding to 81 000 produced τ+τ- events. No candidates were found for either of the two modes. This yields branching ratio upper limits of B(τ → eγ) < 1.1 × 10-4 and B(τ → μγ) < 6.2 × 10-5 at 90% confidence level. © 1995.
ABREU P, ADAM W, ADYE T, et al., 1995, UPPER LIMITS ON THE BRANCHING RATIOS TAU-]MU-GAMMA AND TAU-]E-GAMMA, PHYSICS LETTERS B, Vol: 359, Pages: 411-421, ISSN: 0370-2693
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- Citations: 13
ABREU P, ADAM W, ADYE T, et al., 1995, LIFETIME AND PRODUCTION-RATE OF BEAUTY BARYONS FROM Z-DECAYS, ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS, Vol: 68, Pages: 375-390, ISSN: 0170-9739
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- Citations: 36
ADAM W, ADYE T, AGASI E, et al., 1995, LIFETIME OF CHARGED AND NEUTRAL B-HADRONS USING EVENT TOPOLOGY, ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS, Vol: 68, Pages: 363-374, ISSN: 0170-9739
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- Citations: 24
ABREU P, ADAM W, ADYE T, et al., 1995, B-ASTERISK PRODUCTION IN Z-DECAYS, ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS, Vol: 68, Pages: 353-362, ISSN: 0170-9739
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- Citations: 46
ABREU P, ADAM W, ADYE T, et al., 1995, A MEASUREMENT OF THE TAU-LEPTONIC BRANCHING FRACTIONS, PHYSICS LETTERS B, Vol: 357, Pages: 715-724, ISSN: 0370-2693
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- Citations: 9
Abreu P, Adam W, Adye T, et al., 1995, B<sup>*</sup> production in Z decays, Zeitschrift für Physik C Particles and Fields, Vol: 68, Pages: 353-362, ISSN: 0170-9739
The decay B*→Bγ has been observed with the DELPHI detector at LEP, where the B* meson is produced in Z boson decays. The combination of inclusively reconstructed B mesons with well-measured converted photons yields a measurement of the flavour-averaged B*-B mass difference of 45.5±0.3 (stat.) ±0.8 (syst.) MeV/c2. 95% confidence level upper limits at 6 MeV/c2 are placed on both the isospin (i.e. B+-B0) and the Bs-Bud splitting of the mass difference. The production ratio of B* to B mesons in Z decays is measured to be 0.72±0.03 (stat.) ±0.06 (syst.). Limits on the production cross-section of other hypothetical excited B hadron states decaying radiatively are established. The differential B* cross section has been measured to be in good agreement with the average b fragmentation, yielding an average fractional B* energy of 〈xE〉=0.695±0.009 (stat.) ±0.013 (syst.). From the decay angular distribution the relative contribution of longitudinal B* polarisation states is measured to be σL/(σL + σT) = 0.32 ± 0.04 (stat.) ±0.03 (syst.). © 1995 Springer-Verlag.
ABREU P, ADAM W, ADYE T, et al., 1995, SEARCH FOR EXCLUSIVE CHARMLESS B-MESON DECAYS WITH THE DELPHI DETECTOR AT LEP, PHYSICS LETTERS B, Vol: 357, Pages: 255-266, ISSN: 0370-2693
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- Citations: 5
ABREU P, ADAM W, ADYE T, et al., 1995, A MEASUREMENT OF B+ AND B-0 LIFETIMES USING (D)OVER-BAR-L(+) EVENTS, ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS, Vol: 68, Pages: 13-23, ISSN: 0170-9739
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- Citations: 19
ABREU P, ADAM W, ADYE T, et al., 1995, STRANGE BARYON PRODUCTION IN Z-HADRONIC DECAYS, ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS, Vol: 67, Pages: 543-553, ISSN: 0170-9739
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- Citations: 42
ABREU P, ADAM W, ADYE T, et al., 1995, OBSERVATION OF SHORT-RANGE 3-PARTICLE CORRELATIONS IN E(+)E(-) ANNIHILATIONS AT LEP ENERGIES, PHYSICS LETTERS B, Vol: 355, Pages: 415-424, ISSN: 0370-2693
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- Citations: 42
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