Search results for "Proton"
showing 10 items of 5886 documents
Measurement of the differential cross-section of highly boosted top quarks as a function of their transverse momentum ins=8 TeVproton-proton collisi…
2016
The differential cross-section for pair production of top quarks with high transverse momentum is measured in 20.3 fb(-1) of proton-proton collisions at a center-of-mass energy of 8 TeV. The measur ...
Role of the Δ Resonance in the Population of a Four-Nucleon State in the Fe56→Fe54 Reaction at Relativistic Energies
2016
The 54Fe nucleus was populated from a 56Fe beam impinging on a Be target with an energy of E=A ¼ 500 MeV. The internal decay via γ-ray emission of the 10þ metastable state was observed. As the structure of this isomeric state has to involve at least four unpaired nucleons, it cannot be populated in a simple two-neutron removal reaction from the 56Fe ground state. The isomeric state was produced in the low-momentum (-energy) tail of the parallel momentum (energy) distribution of 54Fe, suggesting that it was populated via the decay of the Δ0 resonance into a proton. This process allows the population of fournucleon states, such as the observed isomer. Therefore, it is concluded that the obser…
Beam-Recoil Polarization Measurement of π0 Electroproduction on the Proton in the Region of the Roper Resonance
2017
The helicity-dependent recoil proton polarizations P_{x}^{'} and P_{z}^{'} as well as the helicity-independent component P_{y} have been measured in the p(e[over →],e^{'}p[over →])π^{0} reaction at four-momentum transfer Q^{2}≃0.1 GeV^{2}, center-of-mass proton emission angle θ_{p}^{*}≃90°, and invariant mass W≃1440 MeV. This first precise measurement of double-polarization observables in the energy domain of the Roper resonance P_{11}(1440) by exploiting recoil polarimetry has allowed for the extraction of its scalar electroexcitation amplitude at an unprecedentedly low value of Q^{2}, establishing a powerful instrument for probing the interplay of quark and meson degrees of freedom in t…
Tevatron Combination of Single-Top-Quark Cross Sections and Determination of the Magnitude of the Cabibbo-Kobayashi-Maskawa Matrix Element Vtb
2015
et al.
Measurement of the top quark-pair production cross section with ATLAS in pp collisions at $\sqrt{s}=7$ TeV
2011
A measurement of the production cross-section for top quark pairs($\ttbar$) in $pp$ collisions at $\sqrt{s}=7 \TeV$ is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron $e$ or muon $\mu$) with large missing transverse energy and at least four jets, and dilepton ($ee$, $\mu\mu$ or $e\mu$) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb-1, 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-$\ttbar$ Standard Model processes are estimated using data-driv…
Search for anomalous heavy-flavor quark production in association with W bosons.
2004
We present a search for anomalous production of heavy-flavor quark jets in association with a W boson at the Fermilab Tevatron ppbar Collider. This search is conducted through an examination of the exclusive jet spectrum of W+jets final states in which the heavy-flavor quark content has been enhanced by requiring at least one tagged jet in an event. Jets are tagged by the combined use of two algorithms, one based on semileptonic decays of b/c hadrons, and the other on their lifetimes. We compare data in e+jets (164 pb-1) and mu+jets (145 pb-1) channels, collected with the D0 detector at sqrt{s}=1.96 TeV, to expectations from the standard model, and set upper limits on anomalous production o…
In depth analysis of the combined HERA data in the dipole models with and without saturation
2018
We present an updated impact parameter dependent saturation model (IPsat) determined trough a fit to the combined HERA I and I+II reduced cross section data. The same HERA data are used to fit the linearized (IPnonsat) version of the applied dipole amplitude, which makes it possible to estimate the magnitude of the saturation effects in various experiments. We find that both parametrizations provide comparable descriptions of the considered data when an effective confinement scale dynamics is incorporated with quark masses. Moreover, it is possible to consistently determine the light and charm quark masses. The role of potentially non-perturbatively large dipoles is examined in detail, with…
Random quasi-phase matching in congruent lithium tantalate waveguides by proton exchange
2012
A report is presented on broadband second-harmonic generation in the range between 930 and 970 nm using random quasi-phase matching in a planar waveguide fabricated by soft proton exchange in congruent lithium tantalate. Bulk and waveguide measurements are compared, outlining the averaging role of guided-wave modes and their interactions with respect to spectral acceptance and near-field profile.
The Medium-Depending Fluorescence of Quadrupolar Donor-Acceptor-Donor Substituted Distyrylbenzenes with High Two-Photon Absorption Cross-Sections
2006
ABSTRACT1,4-Distyrylbenzenes with terminal dialkylamino groups and a central 2,5-disubstitution with electron-accepting groups were prepared via twofold Horner-olefination. These chromophores with a quadrupolar donor-acceptor-donor substitution and C2-symmetry absorb in the violet to green region of the visible spectrum exhibit large two-photon-absorption cross-sections when irrdiated in the NIR. Whereas a variation of the solvent polarity only slightly alters the absorption spectra, the fluorescence appears to be highly responsive. Besides a positive solvatochromism, the emission is very sensitive towards protonation. Quenching or appearance of new emitting species depends on the substitut…
Aza–oxa macrocyclic ligands functionalised with naphthylmethyl fluorescent groups
2000
Abstract Compounds L 1 and L 2 were obtained by reaction of 2-(bromomethyl)naphthalene with 1,4,10-trioxa-7,13-diazacyclopentadecane and 1,4,7-trioxa-10-azacyclododecane, respectively. These receptors contain aza–oxa crowns attached covalently to fluorescent groups. The protonation and coordination behaviour of L 1 and L 2 against metal ions has been studied in dioxane:water (70:30 v/v, 25°C, 0.1 M potassium nitrate) using potentiometric methods. All metal ions studied form complexes with L 1 and L 2 with the logarithm of the formation constants L+M 2+ =[M(L)] 2+ in the sequence Cd 2+ ≅Pb 2+ , Zn 2+ 2+ for L 1 and Zn 2+ 2+ 2+ 2+ 2+ for L 2 . The fluorescent behaviour of L 1 and L 2 was stud…