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result(s) for
"Faulkner, P.J.W."
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Elastic J/ψ production at HERA
Cross sections for elastic production of J/ψ mesons in photoproduction and electroproduction are measured in electron proton collisions at HERA using an integrated luminosity of 55 pb-1. Results are presented for photon virtualities Q2 up to 80 GeV2. The dependence on the photon-proton centre of mass energy Wγp is analysed in the range 40≤Wγp≤305 GeV in photoproduction and 40≤Wγp≤160 GeV in electroproduction. The Wγp dependences of the cross sections do not change significantly with Q2 and can be described by models based on perturbative QCD. Within such models, the data show a high sensitivity to the gluon density of the proton in the domain of low Bjorken x and low Q2. Differential cross sections dσ/dt, where t is the squared four-momentum transfer at the proton vertex, are measured in the range |t|<1.2 GeV2 as functions of Wγp and Q2. Effective Pomeron trajectories are determined for photoproduction and electroproduction. The J/ψ production and decay angular distributions are consistent with s-channel helicity conservation. The ratio of the cross sections for longitudinally and transversely polarised photons is measured as a function of Q2 and is found to be described by perturbative QCD based models.
Journal Article
Measurement of deeply virtual Compton scattering at HERA
A measurement is presented of elastic deeply virtual Compton scattering \\(\\gamma^* p \\rightarrow {\\ensuremath{\\gamma}} p\\) made using e + p collision data corresponding to a luminosity of 46.5 pb-1, taken with the H1 detector at HERA. The cross section is measured as a function of the photon virtuality, Q 2, the invariant mass of the p system, W, and for the first time, differentially in the squared momentum transfer at the proton vertex, t, in the kinematic range \\(2 < Q^{ 2} < 80 {\\rm GeV}^2\\), \\(30 < W < 140 {\\rm GeV}\\) and \\(\\vert t\\vert < 1 {\\rm GeV}^2\\). QCD based calculations at next-to-leading order using generalized parton distributions can describe the data, as can colour dipole model predictions.
Journal Article
Diffractive deep-inelastic scattering with a leading proton at HERA
The cross section for the diffractive deep-inelastic scattering process ep→eXp is measured, with the leading final state proton detected in the H1 Forward Proton Spectrometer. The data analysed cover the range xIP<0.1 in fractional proton longitudinal momentum loss, 0.08<|t|<0.5 GeV-2 in squared four-momentum transfer at the proton vertex, 2
Journal Article
Measurement and QCD analysis of neutral and charged current cross sections at HERA
The inclusive e+psingle and double differential cross sections for neutral and charged current processes are measured with the H1 detector at HERA. The data were taken in 1999 and 2000 at a centre-of-mass energy of \\(\\sqrt{s} = 319{\\rm GeV}\\) and correspond to an integrated luminosity of 65.2 pb-1. The cross sections are measured in the range of four-momentum transfer squared Q2 between 100 and \\(30 000{\\rm GeV}^2\\) and Bjorken x between 0.0013 and 0.65. The neutral current analysis for the new e+p data and the earlier e-p data taken in 1998 and 1999 is extended to small energies of the scattered electron and therefore to higher values of inelasticity y, allowing a determination of the longitudinal structure function FL at high Q2 (\\(110-700{\\rm GeV}^2\\)). A new measurement of the structure function \\(x\\tilde{F}_3\\) is obtained using the new e+p and previously published \\(e^\\pm p\\) neutral current cross section data at high Q2. These data together with H1 low Q2 precision data are further used to perform new next-to-leading order QCD analyses in the framework of the Standard Model to extract flavour separated parton distributions in the proton.
Journal Article
Tests of QCD factorisation in the diffractive production of dijets in deep-inelastic scattering and photoproduction at HERA
Measurements are presented of differential dijet cross sections in diffractive photoproduction (Q2<0.01 GeV2) and deep-inelastic scattering processes (DIS, 4
Journal Article
Diffractive open charm production in deep-inelastic scattering and photoproduction at HERA
Measurements are presented of diffractive open charm production at HERA. The event topology is given by ep→eXY where the system X contains at least one charmed hadron and is well separated by a large rapidity gap from a leading low-mass proton remnant system Y. Two analysis techniques are used for the cross section measurements. In the first, the charm quark is tagged by the reconstruction of a D*±(2010) meson. This technique is used in deep-inelastic scattering (DIS) and photoproduction (γp). In the second, a method based on the displacement of tracks from the primary vertex is used to measure the open charm contribution to the inclusive diffractive cross section in DIS. The measurements are compared with next-to-leading order QCD predictions based on diffractive parton density functions previously obtained from a QCD analysis of the inclusive diffractive cross section at H1. A good agreement is observed in the full kinematic regime, which supports the validity of QCD factorization for open charm production in diffractive DIS and γp.
Journal Article
Elastic electroproduction of$\\rho$mesons at HERA
The elastic electroproduction of rho mesons is studied at HERA with the H1 detector for a photon virtuality in the range 1 Q² 60 GeV² and for a hadronic centre of mass energy in the range 30 W 140 GeV. The shape of the pipi mass distribution in the rho resonance region is measured as a function of Q². The full set of rho spin density matrix elements is determined, and evidence is found for a helicity flip amplitude at the level of 8 +- 3 % of the non-flip amplitudes. Measurements are presented of the dependence of the cross section on Q², W and t (the four-momentum transfer squared to the proton). They suggest that, especially at large Q², the gamma^(*)p cross section develops a stronger W dependence than that expected from the behaviour of elastic and total hadron-hadron cross sections.
Journal Article
Measurement of neutral and charged current cross-sections in positron-proton collisions at large momentum transfer
The inclusive single and double differential cross-sections for neutral and charged current processes with four-momentum transfer squared \\(Q^2\\) between 150 and 30 000 GeV\\(^2\\) and with Bjorken x between 0.0032 and 0.65 are measured in \\(e^+ p\\) collisions. The data were taken with the H1 detector at HERA between 1994 and 1997, and they correspond to an integrated luminosity of \\(35.6\\,{\\rm pb}^{-1}\\). The \\(Q^2\\) evolution of the parton densities of the proton is tested, yielding no significant deviation from the prediction of perturbative QCD. The proton structure function \\(F_2(x,Q^2)\\) is determined. An extraction of the u and d quark distributions at high x is presented. At high \\(Q^2\\) electroweak effects of the heavy bosons \\(Z^\\circ\\) and \\(W\\) are observed and found to be consistent with Standard Model expectation.
Journal Article
Measurement of beauty production at HERA using events with muons and jets
A measurement of the beauty production cross section in ep collisions at a centre-of-mass energy of 319 GeV is presented. The data were collected with the H1 detector at the HERA collider in the years 1999-2000. Events are selected by requiring the presence of jets and muons in the final state. Both the long lifetime and the large mass of b-flavoured hadrons are exploited to identify events containing beauty quarks. Differential cross sections are measured in photoproduction, with photon virtualities Q2 < 1 GeV2, and in deep inelastic scattering, where 2 < Q2 < 100 GeV2. The results are compared with perturbative QCD calculations to leading and next-to-leading order. The predictions are found to be somewhat lower than the data.
Journal Article
Forward jet production in deep inelastic scattering at HERA
The production of forward jets has been measured in deep inelastic ep collisions at HERA. The results are presented in terms of single differential cross sections as a function of the Bjorken scaling variable (xBj) and as triple differential cross sections d3σ/dxBjdQ2, where Q2 is the four momentum transfer squared and is the squared transverse momentum of the forward jet. Also cross sections for events with a di-jet system in addition to the forward jet are measured as a function of the rapidity separation between the forward jet and the two additional jets. The measurements are compared with next-to-leading order QCD calculations and with the predictions of various QCD-based models.
Journal Article