| 1. |
- Edelson, R. A., et al.
(författare)
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Multiwavelength observations of short-timescale variability in NGC 4151. IV. Analysis of multiwavelength continuum variability
- 1996
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 470:1, s. 364-377377
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Tidskriftsartikel (refereegranskat)abstract
- For pt.III see ibid., vol.470, no.1, p.349-63 (1996). Combines data from the three preceding papers in order to analyze the multi wave-band variability and spectral energy distribution of the Seyfert 1 galaxy NGC 4151 during the 1993 December monitoring campaign. The source, which was near its peak historical brightness, showed strong, correlated variability at X-ray, ultraviolet, and optical wavelengths. The strongest variations were seen in medium-energy (~1.5 keV) X-rays, with a normalized variability amplitude (NVA) of 24%. Weaker (NVA=6%) variations (uncorrelated with those at lower energies) were seen at soft gamma-ray energies of ~100 keV. No significant variability was seen in softer (0.1-1 keV) X-ray bands. In the ultraviolet/optical regime, the NVA decreased from 9% to 1% as the wavelength increased from 1275 to 6900 Aring. These data do not probe extreme ultraviolet (1200 Aring to 0.1 keV) or hard X-ray (250 keV) variability. The phase differences between variations in different bands were consistent with zero lag, with upper limits of lsim0.15 day between 1275 Aring and the other ultraviolet bands, lsim0.3 day between 1275 Aring and 1.5 keV, and lsim1 day between 1275 and 5125 Aring. These tight limits represent more than an order of magnitude improvement over those determined in previous multi-wave-band AGN monitoring campaigns. The ultraviolet fluctuation power spectra showed no evidence for periodicity, but were instead well fitted with a very steep, red power law (ales-2.5)
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| 2. |
- Abreu, P, et al.
(författare)
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A precise measurement of the partial decay width ratio R-b(0) = Gamma(b(b)over-bar)/Gamma(had)
- 1999
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Ingår i: EUROPEAN PHYSICAL JOURNAL C. - : SPRINGER VERLAG. - 1434-6044. ; 10:3, s. 415-442
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The partial decay width of the Z to b (b) over bar quark pairs has been measured by the DELPHI detector at LEP using data taken in the years 1992 to 1995. Decays of b-hadrons were tagged by several methods using tracks with large impact parameters and/or
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| 3. |
- Abreu, P, et al.
(författare)
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A search for invisible Higgs bosons produced in e(+)e(-) interactions at LEP 2 energies
- 1999
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Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 459:1-3, s. 367-381
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Searches for HZ production with the Higgs boson decaying into an invisible final state have been performed with the data collected by the DELPHI experiment up to the centre-of-mass energy of 183 GeV. The hadronic and muon pair final states of the Z boson
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| 4. |
- Abreu, P, et al.
(författare)
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Energy dependence of event shapes and of alpha(s) at LEP 2
- 1999
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Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 456:2-4, s. 322-340
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Infrared and collinear safe event shape distributions and their mean values are determined using the data taken at five different centre of mass energies above M-Z with the DELPHI detector at LEP. From the event shapes, the strong coupling alpha(s) is ext
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| 5. |
- Abreu, P, et al.
(författare)
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Energy dependence of inclusive spectra in e(+)e(-) annihilation
- 1999
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Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 459:1-3, s. 397-411
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Inclusive charged hadron distributions as obtained from the DELPHI measurements at 130, 136, 161, 172 and 183 GeV are presented as a function of the variables rapidity, xi(p), p and transversal momenta. Data are compared with event generators and with MLL
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| 6. |
- Abreu, P, et al.
(författare)
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Measurement and interpretation of fermion-pair production at LEP energies from 130 to 172 GeV
- 1999
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Ingår i: EUROPEAN PHYSICAL JOURNAL C. - : SPRINGER VERLAG. - 1434-6044. ; 11:3, s. 383-407
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Tidskriftsartikel (refereegranskat)abstract
- The data collected with the DELPHI detector at centre-of-mass energies between 130 and 172 GeV, during LEP operation in 1995 and 1996, have been used to determine the hadronic and leptonic cross-sections and leptonic forward-backward asymmetries. In addit
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| 7. |
- Abreu, P, et al.
(författare)
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Measurement of A(FB)(b(b)over-bar) in hadronic Z decays using a jet charge technique
- 1999
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Ingår i: EUROPEAN PHYSICAL JOURNAL C. - : SPRINGER VERLAG. - 1434-6044. ; 9:3, s. 367-381
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The bb forward-backward asymmetry has been determined from the average charge how measured in a sample of 3,500,000 hadronic Z decays collected with the DELPHI detector in 1992 - 1995. The measurement is performed in an enriched b (b) over bar sample sele
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| 8. |
- Abreu, P, et al.
(författare)
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Measurement of inclusive rho(0), f(0)(980), f(2)(1270), K-2(*0)(1430) and f '(2)(1525) production in Z(0) decays
- 1999
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Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 449:3-4, s. 364-382
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- DELPHI results are presented on the inclusive production of the neutral mesons rho(0), f(0)(980), f(2)(1270), K-2(*0)(1430) and f'(2)(1525) in hadronic Z(0) decays. They are based on about 2 million multihadronic events collected in 1994 and 1995, using t
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| 9. |
- Abreu, P, et al.
(författare)
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Measurement of the lifetime of b-baryons
- 1999
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Ingår i: EUROPEAN PHYSICAL JOURNAL C. - : SPRINGER VERLAG. - 1434-6044. ; 10:2, s. 185-199
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The average lifetime of weakly decaying b-baryons was studied using 3.6 million Z(0) hadronic decays collected by the DELPHI detector at LEP. The measurement of the proper decay time distribution of secondary vertices was used on three complementary sampl
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| 10. |
- Abreu, P, et al.
(författare)
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Measurement of the mass of the W boson using direct reconstruction at root s=183 GeV
- 1999
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Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 462:3-4, s. 410-424
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- From data corresponding to an integrated luminosity of 53.5 pb(-1) taken during the 183 GeV run in 1997, DELPHI has measured the W mass from direct reconstruction of WW --> l<(nu)over bar>q (q) over bar and WW --> q (q) over bar q (q) over bar events. Com
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