| 41. |
- Abdallah, J, et al.
(författare)
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Measurement of the e(+)e(-)-> W+W- gamma cross-section and limits on anomalous quartic gauge couplings with DELPHI
- 2003
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 31:2, s. 139-147
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Tidskriftsartikel (refereegranskat)abstract
- W(+)W(-)gamma production at LEP2 is studied using data collected with the DELPHI detector at centre-of-mass energies between 189 GeV and 209 GeV, corresponding to an integrated luminosity of about 600 pb(-1). Cross-sections are measured for the production of W+W- with a hard, central and isolated photon in the final state, and are found to be compatible with the Standard Model prediction. The photon energy spectra are used to derive limits on anomalous contributions to the W(+)W(-)Z(o)gamma and W(+)W(-)gammagamma vertices.
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| 42. |
- Abdallah, J, et al.
(författare)
-
Measurement of the Lambda(0)(b) decay form factor
- 2004
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 585:1-2, s. 63-84
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Tidskriftsartikel (refereegranskat)abstract
- The form factor of A(o)(b) baryons is estimated using 3.46 x 10(6) hadronic Z decays collected by the DELPM experiment between 1992 and 1995. Charmed A(c)(+) baryons fully reconstructed in the pK(-)pi(+), pK(o)(s), and Api(+)pi(+)pi(-) modes, are associated to a c S lepton with opposite charge in order to select A(o)(b) --> A(c)(+)l(-)v(l) decays. From a combined likelihood and event rate fit to the b C distribution of the Isgur-Wise variable w, and using the Heavy Quark Effective Theory (HQET), the slope of the b-baryon form factor is measured to be p(2)=2.03+/-0.46(stat)(-1.00)(+0.72)(syst). The exclusive semileptonic branching fraction Br(A(b)(o) --> A(c)(+)l(-)v(l)) can be derived from p(2) and is found to be (5.0(-0.8)(+1.1)(stat)(-1.2)(+1.6) (syst))%. Limits on other branching fractions are also obtained. (C) 2004 Published by Elsevier B.V.
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| 43. |
- Abdallah, J, et al.
(författare)
-
Search for an LSP gluino at LEP with the DELPHI detector
- 2003
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 26:4, s. 505-525
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Tidskriftsartikel (refereegranskat)abstract
- In some supersymmetric models, the gluino ((g) over tilde) is predicted to be light and stable. In that case, it would hadronize to form R-hadrons. In these models, the missing energy signature of the lightest supersymmetric particle is no longer valid, even if R-parity is conserved. Therefore, such a gluino is not constrained by hadron collider results, which looked for the decay (g) over tilde --> q (q) over bar(χ) over tilde (0)(1). Data collected by the DELPHI detector in 1994 at 91.2 GeV have been analysed to search for q (q) over bar(gg) over tilde events. No deviation from Standard Model predictions is observed and a gluino mass between 2 and 18 GeV/c(2) is excluded at the 95% confidence level in these models. Then, R-hadrons produced in the squark decays were searched for in the data collected by DELPHI at the centre-of-mass energies of 189 to 208 GeV, corresponding to an overall integrated luminosity of 609 pb(-1). The observed number of events is in agreement with the Standard Model predictions. Limits at 95% confidence level are derived on the squark masses from the excluded regions in the plane (m((q) over tilde1),m((g) over bar)): m((t) over tilde1) > 90 GeV/c(2) and m((b) over tilde1) > 96 GeV/c(2) for purely left squarks. m((t) over tilde1) > 87 GeV/c(2) and m((b) over tilde1) > 82 GeV/c(2) independent of the mixing angle.
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| 44. |
- Abdallah, J, et al.
(författare)
-
Search for B-s(0)-(B-s(0))over-bar oscillations and a measurement of B-d(0)-(B-d(0))over-bar oscillations using events with an inclusively reconstructed vertex
- 2003
-
Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 28:2, s. 155-173
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Tidskriftsartikel (refereegranskat)abstract
- Neutral B meson oscillations in the B-s(0) - <(B-s(0))over bar>, and B-d(0) - <(B-d(0))over bar> systems were studied using a sample of about 4.0 million hadronic Z decays recorded by the DELPHI detector between 1992 and 2000. Events with a high transverse momentum lepton were removed and a sample of 770 k events with an inclusively reconstructed vertex was selected. The mass difference between the two physical states in the B-d(0) - <(B-d(0))over bar>system was measured to be: Deltam(d) = (0.531 +/- 0.025(stat.) +/- 0.007(syst.))ps(-1). The following limit on the width difference of these states was also obtained: DeltaGamma(Bd)/Gamma(Bd) < 0.18 at 95% CL. As no evidence for B-s(0) -<(B-s(0))over bar> oscillations was found, a limit on the mass difference of the two physical states was given:, Deltam(s) > 5.0 ps(-1) at 95% CL. The corresponding sensitivity of this analysis is equal to 6.6 ps(-1).
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| 45. |
- Abdallah, J, et al.
(författare)
-
Search for resonant (nu)over-tilde production at root s=183 to 208 GeV
- 2003
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 28:1, s. 15-26
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Tidskriftsartikel (refereegranskat)abstract
- Searches for resonant (ν) over tilde production in e(+)e(-) collisions under the assumption that R-parity is not conserved and that the dominant R-parity violating coupling is lambda(121) or lambda(131) used data recorded by DELPHI in 1997 to 2000 at centre-of-mass energies of 183 to 208 GeV. No deviation from the Standard Model was observed. Upper limits are given for the lambda(121) and lambda(131) couplings as a function of the sneutrino mass and total width. The limits are especially stringent for sneutrino masses equal to the centre-of-mass energies with the highest integrated luminosities recorded.
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| 46. |
- Abdallah, J, et al.
(författare)
-
Search for supersymmetric particles in light gravitino scenarios and sleptons NLSP
- 2003
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 27:2, s. 153-172
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Tidskriftsartikel (refereegranskat)abstract
- A search for sleptons, neutralinos, charginos, sgoldstinos and heavy stable charged sleptons in the context of scenarios where the lightest supersymmetric particle is the gravitino, is presented. Data collected during 2000 with the DELPHI detector at centre-of-mass energies from 204 to 208 GeV were analysed and combined with all the data collected from 1995 to 1999 at lower energies. No evidence for the production of sleptons, neutralinos and charginos has been found, therefore new limits on the mass of these supersymmetric particles and on the model parameter space are set. The search for heavy stable charged sleptons also updates the stable sleptons mass limit. The absence of evidence for sgoldstino production allows limits to be set on its mass and on the scale of supersymmetry breaking.
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| 47. |
- Abdallah, J, et al.
(författare)
-
Searches for supersymmetric particles in e(+)e(-) collisions up to 208 GeV and interpretation of the results within the MSSM
- 2003
-
Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 31:4, s. 421-479
-
Tidskriftsartikel (refereegranskat)abstract
- DELPHI data collected at centre-of-mass energies up to 208 GeV have been analysed to search for charginos, neutralinos and sfermions in the framework of the Minimal Supersymmetric Standard Model (MSSM) with R-parity conservation. No evidence for a signal was found in any of the channels. The results of each search were used to derive limits on production cross-sections and particle masses. In addition, the combined result of all searches excludes regions in the parameter space of the constrained MSSM, leading to limits on the mass of the Lightest Supersymmetric Particle and other supersymmetric particles.
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| 48. |
- Abdallah, J, et al.
(författare)
-
The eta(c)(2980) formation in two-photon collisions at LEP energies
- 2003
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 31:4, s. 481-489
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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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| 49. |
- 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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| 50. |
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