Forward pi^0 Production and Associated Transverse Energy Flow in Deep-Inelastic Scattering at HERA

Deep-inelastic positron-proton interactions at low values of Bjorken-x down to x \approx 4.10^-5 which give rise to high transverse momentum pi^0 mesons are studied with the H1 experiment at HERA. The inclusive cross section for pi^0 mesons produced at small angles with respect to the proton remnant (the forward region) is presented as a function of the transverse momentum and energy of the pi^0 and of the four-momentum transfer Q^2 and Bjorken-x. Measurements are also presented of the transverse energy flow in events containing a forward pi^0 meson. Hadronic final state calculations based on QCD models implementing different parton evolution schemes are confronted with the data.Comment: 27 pages, 8 figures and 3 table

Inelastic photoproduction of J/Psi mesons at HERA

An analysis of inelastic photoproduction of J/Psi mesons is presented using data collected at the ep collider HERA corresponding to an integrated luminosity of above 80pb-1. Differential and double differential cross sections are measured in a wide kinematic region: 6

Inelastic Leptoproduction of J/Psi Mesons at HERA

The leptoproduction of J/psi mesons is studied in inelastic reactions for four momentum transfers 2<Q^2<100GeV^2. The data were taken with the H1 detector at the electron proton collider HERA and correspond to an integrated luminosity of 77 pb-1. Single differential and double differential cross sections are measured with increased precision compared with previous analyses. New leading order calculations within the non-relativistic QCD factorisation approach including colour octet and colour singlet contributions are compared with the data and are found to give a reasonable description of most distributions. An exception is the shape of the distribution in the J/psi fractional energy, z, which deviates significantly from that of the data. Comparisons with photoproduction are made and the polarisation of the produced J/psi meson is analysed.Comment: 27 pages, 7 figures and 7 table

Rare phenomenon and W production in electron-proton scattering at HERA

A general and model-independent search for deviations from the standard model prediction is performed in ep collisions at HERA using H1 data corresponding to an integrated luminosity of 115 pb&quot;-&quot;1. All experimentally measurable event topologies involving electrons, photons, muons, neutrinos and jets with high transverse momenta are investigated. Events are classified into exclusive event classes according to their final state. A new algorithm is used to look for regions with deviations from the standard model in the invariant mass and sum of transverse momenta distributions and to quantify the significance of the observed deviations. A good agreement with the standard model prediction is found in most of the event classes. The largest deviation occurs in topologies with an isolated muon, missing transverse momentum and a jet. About 2% of hypothetical Monte Carlo experiments would produce deviations more significant than the one observed in the corresponding sum of transverse momenta distribution. Within the standard model events with an isolated muon, or, more general, a charged lepton, and missing transverse momentum are expected to be mainly due to W boson production with subsequent leptonic decay. The H1 and ZEUS collaborations have already searched for such events and found, in accordance with the general search, an excess of events with high transverse momentum of the hadronic system. Complementary, a search for W bosons in the dominant hadronic decay channel is performed. The phase space is optimised to maximise the acceptance for W events and reduce other standard model contributions. The data are compared to the predictions of quantum chromodynamics as a function of the transverse momentum of the hadronic system after excluding the W candidate jets and found to be in good agreement in this regard. (orig.)Available from TIB Hannover: RA 8919(2004-048) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Sliding/Rolling Phobic Droplets along a Fiber: Measurement of Interfacial Forces

Phobic droplet–fiber systems possess complex geometries, which have made full characterization of such systems difficult. This work has used atomic force microscopy (AFM) to measure droplet–fiber forces for oil droplets on oleophobic fibers over a range of fiber diameters. The work adapted a previous method and a theoretical model developed by the authors for philic droplet–fiber systems. A Bayesian statistical model was also used to account for the influence of surface roughness on the droplet–fiber force. In general, it has been found that the force required to move a liquid droplet along an oleophobic filter fiber will be less than that required to move a droplet along an oleophilic fiber. However, because of the effects of pinning and/or wetting behavior, this difference may be less than would otherwise be expected. Droplets with a greater contact angle ( 110°) were observed to roll along the fiber, whereas droplets with a lesser contact angle (<90°) would slide