| 51. |
- 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 Science and Business Media LLC. - 1434-6044. ; 35:2, s. 159-170
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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.
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| 52. |
- Abdallah, J, et al.
(författare)
-
The eta(c)(2980) formation in two-photon collisions at LEP energies
- 2003
-
Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 31:4, s. 481-489
-
Tidskriftsartikel (refereegranskat)abstract
- eta(c)(2980) production in gammagamma interactions has been detected via its decays into K(s)(0)K(-/+)pi(-/+), K+K-K+K- and K(+)K(-)pi(+)pi(-) in the data taken with the DELPHI detector at LEP1 and LEP2 energies. The two-photon radiative width averaged over all observed decay channels is Gammagammagamma=13.9+/-2.0(stat.)+/-1.4(syst.)+/-2.7 (BR) keV. No direct decay channel eta(c)-->pi(+)pi(-)pi(+)pi(-) has been observed. An upper limit Gamma(gammagamma)<5.5 keV at 95% confidence level has been evaluated for this decay mode.
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| 53. |
- Abdallah, J, et al.
(författare)
-
The measurement of alpha(8) from event shapes with the DELPHI detector at the highest LEP energies
- 2004
-
Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 37:1, s. 1-23
-
Tidskriftsartikel (refereegranskat)abstract
- Hadronic event shape distributions are determined from data in e(+)e(-) collisions between 183 and 207 GeV. From these the strong coupling alpha(s) is extracted in O(alpha(s)(2)), NLLA and matched O(alpha(s)(2))+ NLLA theory. Hadronisation corrections evaluated with fragmentation model generators as well as an analytical power ansatz are applied. Comparing these measurements to those obtained at and around M-Z allows a combined measurement of alpha(s) from all DELPHI data and a test of the energy dependence of the strong coupling.
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| 54. |
- Abdallah, J, et al.
(författare)
-
ZZ production in e(+) e(-) interactions at root s=183-209 GeV
- 2003
-
Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 30:4, s. 447-466
-
Tidskriftsartikel (refereegranskat)abstract
- Measurements of on-shell ZZ production are described, using data from the DELPHI experiment at LEP in e(+)e(-) collisions at centre-of-mass energies between 183 and 209 GeV, corresponding to an integrated luminosity of about 665 pb(-1). Results obtained in each of the final states q (q) over barq (q) over bar, nu(ν) over barq (q) over bar, mu(+)mu(-) q (q) over bar, e(+)e(-) r(+)r(-) q (q) over bar, l(+)l(-)l(+)l(-), and nu(ν) over barl(+)l(-) (with l = e, mu) are presented. The measured production cross-sections are consistent with the Standard Model expectations. These results update and supersede those already published at 183 and 189 GeV.
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| 55. |
- Abreu, P, et al.
(författare)
-
b-tagging in DELPHI at LEP
- 2004
-
Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 32:2, s. 185-208
-
Tidskriftsartikel (refereegranskat)abstract
- The standard method used for tagging b-hadrons in the DELPHI experiment at the CERN LEP Collider is discussed in detail. The main ingredient of b-tagging is the impact parameters of tracks, which relies mostly on the vertex detector. Additional information, such as the mass of particles associated to a secondary vertex, significantly improves the selection efficiency and the background suppression. The paper describes various discriminating variables used for the tagging and the procedure of their combination. In addition, applications of b-tagging to some physics analyses, which depend crucially on the performance and reliability of b-tagging, are described briefly.
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| 56. |
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| 57. |
- Abreu, P, et al.
(författare)
-
Measurement and interpretation of the W-pair cross-section in e(+)e(-) interactions at 161 GeV
- 1997
-
Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 397:1-2, s. 158-170
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In 1996 LEP ran at a centre-of-mass energy of 161 GeV, just above the threshold of W-pair production. DELPHI accumulated data corresponding to an integrated luminosity of 9.93 pb(-1), and observed 29 events that are considered as candidates for W-pair pro
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| 58. |
- Abreu, P, et al.
(författare)
-
Measurement of the e(+)e(-)->gamma gamma(gamma) cross section at the LEP energies
- 1998
-
Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 433:3-4, s. 429-440
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The total and the differential cross-sections for the reaction e(+)e(-) --> gamma gamma(gamma) have been measured with the DELPHI detector at LEP at centre-of-mass energies from 130 to 183 GeV for an integrated luminosity of 78.19 pb(-1). The results agre
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| 59. |
- Abreu, P., et al.
(författare)
-
Measurement of the gluon fragmentation function and a comparison of the scaling violation in gluon and quark jets
- 2000
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 13:4, s. 573-589
-
Tidskriftsartikel (refereegranskat)abstract
- The fragmentation functions of quarks and gluons are measured in various three-jet topologies in Z decays from the full data set collected with the DELPHI detector at the Z resonance between 1992 and 995. The results at different values of transverse momentum-like scales are compared. A parameterization of the quark and gluon fragmentation functions at a fixed reference scale is given. The quark and gluon fragmentation functions show the predicted pattern of scaling violations. The scaling violation for quark jets as a function of a transverse momentum-like scale is in a good agreement with that observed in lower energy e+e- annihilation experiments. For gluon jets it appears to be significantly stronger. The scale dependences of the gluon and quark fragmentation functions agree with the prediction of the DGLAP evolution equations from which the colour factor ratio CA/CF is measured to be: CA/CF = 2.26 ± 0.09stat. ± 0.06sys. ± 0.12clus.,scale..
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| 60. |
- Abreu, P, et al.
(författare)
-
Measurement of the inclusive charmless and double-charm B branching ratios
- 1998
-
Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 426:1-2, s. 193-206
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The DELPHI experiment at LEP has measured the inclusive charmless B hadron decay branching ratio, the B branching ratio into two charmed particles, and the total number of charmed particles per B decay, using the hadronic Z data taken between 1992 and 199
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