1. |
|
|
2. |
|
|
3. |
|
|
4. |
- Aaron, F. D., et al.
(författare)
-
Events with an isolated lepton and missing transverse momentum and measurement of W production at HERA
- 2010
-
Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2010:3, s. 1-19
-
Tidskriftsartikel (refereegranskat)abstract
- A search for events containing an isolated electron or muon and missing trans verse momentum produced in e(+/-)p collisions is performed with the H1 and ZEUS detectors at HERA. The data were taken in the period 1994-2007 and correspond to an integrated luminosity of 0.98 fb(-1). The observed event yields are in good overall agreement with the Standard Model prediction, which is dominated by single W production. In the e(+)p data, at large hadronic transverse momentum P-T(X) > 25GeV, a total of 23 events are observed compared to a prediction of 14.0 +/- 1.9. The total single W boson production cross section is measured as 1.06 +/- 0.16 (stat.) +/- 0.07 (sys.) pb, in agreement with an Standard Model (SM) expectation of 1.26 +/- 0.19 pb.
|
|
5. |
- Aaron, F. D., et al.
(författare)
-
Multi-leptons with high transverse momentum at HERA
- 2009
-
Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; :10
-
Tidskriftsartikel (refereegranskat)abstract
- Events with at least two high transverse momentum leptons (electrons or muons) are studied using the H1 and ZEUS detectors at HERA with an integrated luminosity of 0.94 fb(-1). The observed numbers of events are in general agreement with the Standard Model predictions. Seven di- and tri-lepton events are observed in e(+)p collision data with a scalar sum of the lepton transverse momenta above 100 GeV while 1.94 +/- 0.17 events are expected. Such events are not observed in e(-)p collisions for which 1.19 +/- 0.12 are predicted. Total visible and differential di-electron and di-muon photoproduction cross sections are extracted in a restricted phase space dominated by photon-photon collisions.
|
|
6. |
- Aaron, F. D., et al.
(författare)
-
Combined measurement and QCD analysis of the inclusive e(+/-)p scattering cross sections at HERA
- 2010
-
Ingår i: Journal of High Energy Physics. - 1029-8479. ; :1
-
Tidskriftsartikel (refereegranskat)abstract
- A combination is presented of the inclusive deep inelastic cross sections measured by the H1 and ZEUS Collaborations in neutral and charged current unpolarised e(+/-)p scattering at HERA during the period 1994-2000. The data span six orders of magnitude in negative four-momentum-transfer squared, Q(2), and in Bjorken x. The combination method used takes the correlations of systematic uncertainties into account, resulting in an improved accuracy. The combined data are the sole input in a NLO QCD analysis which determines a new set of parton distributions, HERAPDF1.0, with small experimental uncertainties. This set includes an estimate of the model and parametrisation uncertainties of the fit result.
|
|
7. |
- Aaron, F. D., et al.
(författare)
-
Combined inclusive diffractive cross sections measured with forward proton spectrometers in deep inelastic ep scattering at HERA
- 2012
-
Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 72:10
-
Tidskriftsartikel (refereegranskat)abstract
- A combination of the inclusive diffractive cross section measurements made by the H1 and ZEUS Collaborations at HERA is presented. The analysis uses samples of diffractive deep inelastic ep scattering data at a centre-of-mass energy root s = 318 GeV where leading protons are detected by dedicated spectrometers. Correlations of systematic uncertainties are taken into account, resulting in an improved precision of the cross section measurement which reaches 6 % for the most precise points. The combined data cover the range 2.5 < Q(2) < 200 GeV2 in photon virtuality, 0.00035 < x(P) < 0.09 in proton fractional momentum loss, 0.09 < vertical bar t vertical bar < 0.55 GeV2 in squared four-momentum transfer at the proton vertex and 0.0018 < beta < 0.816 in beta = x/x(P), where x is the Bjorken scaling variable.
|
|
8. |
- Abramowicz, H., et al.
(författare)
-
Combination and QCD analysis of charm production cross section measurements in deep-inelastic ep scattering at HERA
- 2013
-
Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 73:2
-
Tidskriftsartikel (refereegranskat)abstract
- Measurements of open charm production cross sections in deep-inelastic ep scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross sections sigma(c (c) over bar)(red) for charm production are obtained in the kinematic range of photon virtuality 2.5 <= Q(2) <= 2000 GeV2 and Bjorken scaling variable 3 . 10(-5) <= x <= 5 . 10(-2). The combination method accounts for the correlations of the systematic uncertainties among the different data sets. The combined charm data together with the combined inclusive deep-inelastic scattering cross sections from HERA are used as input for a detailed NLO QCD analysis to study the influence of different heavy flavour schemes on the parton distribution functions. The optimal values of the charm mass as a parameter in these different schemes are obtained. The implications on the NLO predictions for W-+/- and Z production cross sections at the LHC are investigated. Using the fixed flavour number scheme, the running mass of the charm quark is determined.
|
|
9. |
|
|
10. |
|
|
11. |
- Busby, CJ, et al.
(författare)
-
The missing half of the subduction factory : shipboard results from the Izu rear arc, IODP expedition 350
- 2017
-
Ingår i: International Geology Review. - : Informa UK Limited. - 0020-6814 .- 1938-2839. ; 59:13, s. 1677-1708
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- IODP Expedition 350 was the first to be drilled in the rear part of the Izu-Bonin, although severalsites had been drilled in the arc axis to fore-arc region; the scientific objective was to understand theevolution of the Izu rear arc, by drilling a deep-water volcaniclastic section with a long temporalrecord (Site U1437). The Izu rear arc is dominated by a series of basaltic to dacitic seamount chainsup to ~100-km long roughly perpendicular to the arc front. Dredge samples from these aregeochemically distinct from arc front rocks, and drilling was undertaken to understand this arcasymmetry. Site U1437 lies in an ~20-km-wide basin between two rear arc seamount chains, ~90-kmwest of the arc front, and was drilled to 1804 m below the sea floor (mbsf) with excellent recovery.We expected to drill a volcaniclastic apron, but the section is much more mud-rich than expected(~60%), and the remaining fraction of the section is much finer-grained than predicted from itsposition within the Izu arc, composed half of ashes/tuffs, and half of lapilli tuffs of fine grain size(clasts <3 cm). Volcanic blocks (>6.4 cm) are only sparsely scattered through the lowermost 25% ofthe section, and only one igneous unit was encountered, a rhyolite peperite intrusion at~1390 mbsf. The lowest biostratigaphic datum is at 867 mbsf (~6.5 Ma), the lowest palaeomagneticdatum is at ~1300 mbsf (~9 Ma), and the rhyolite peperite at ~1390 mbsf has yielded a U–Pb zirconconcordia intercept age of (13.6 + 1.6/−1.7) Ma. Both arc front and rear arc sources contributed tothe fine-grained (distal) tephras of the upper 1320 m, but the coarse-grained (proximal) volcani-clastics in the lowest 25% of the section are geochemically similar to the arc front, suggesting arcasymmetry is not recorded in rocks older than ~13 Ma.
|
|
12. |
- Thapper, Anders, et al.
(författare)
-
The Unperturbed Oxo-Sulfido Functional Group cis-Mo(VI)OS, Related to that in the Xanthine Oxidase Family of Molybdoenzymes: Synthesis, Structural Characterization and Reactivity Aspects
- 1999
-
Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 1520-510X .- 0020-1669. ; 38:18, s. 4104-4114
-
Tidskriftsartikel (refereegranskat)abstract
- The oxo-sulfido functional group cis-MoVIOS is essential to the activity of the xanthine oxidase family of enzymes but has proven elusive to synthesis in molecules containing no other four-electron ligands. A direct route to molecules containing this group has been achieved. The reaction system [MoO2(OSiPh3)2]/L in dichloromethane yields the complexes [MoVIO2(OSiPh3)2L] (L = phen (1), Me4phen (2), 4,4'-Me2bpy (3), 5,5'-Me2bpy (4), 2 py (5)) (74-96%), which are shown to have a distorted octahedral structure of crystallographically imposed C2 symmetry (1, 5) with cis oxo and trans silyloxy ligands. The related reaction system [MoO3S]2-/2Ph3SiCl/L in acetonitrile affords the complexes [MoVIOS(OSiPh3)2L] (L = phen (6), Me4phen (7), 4,4'-Me2bpy (8), 5,5'-Me2bpy (9)) (36-69%). From the collective results of elemental analysis, mass spectrometry, 1H NMR, and X-ray structure determinations (6, 7), complexes 6-9 are shown to contain the cis-MoVIOS group in molecules with the same overall stereochemistry as dioxo complexes 1-5. The crystal structures of 6 and 7 exhibit O/S disorder, which was modeled in refinements with 50% site occupancies. The Mo=O (1.607(5) (6), 1.645(5) (7) Å) and Mo=S (2.257(3) (6), 2.203(2) (7) Å) bond distances obtained in this way are somewhat shorter and longer, respectively, than expected. Distances obtained by molybdenum EXAFS analysis using the GNXAS protocol for 6-9 (Mo=O 1.71-1.72 Å; Mo=S 2.18-2.19 Å) are considered more satisfactory and are in good agreement with EXAFS values for xanthine oxidase. Molybdenum K-edge data for 1 and 6-9 are reported. Reaction of 7 with Ph3P in dichloromethane results in sulfur abstraction and formation of [MoVOCl(OSiPh3)2(Me4phen)] (10), which has a distorted octahedral structure with cis O/Cl and cis silyloxy ligands. Sulfur rather than oxygen abstraction is favored by relative Mo=O/Mo=S bond strengths. Complexes 6-9 should allow exploration of the biologically significant cis-MoVIOS group.
|
|