122 research outputs found
Hard Two-Photon Contribution to Elastic Lepton-Proton Scattering: Determined by the OLYMPUS Experiment
The OLYMPUS collaboration reports on a precision measurement of the
positron-proton to electron-proton elastic cross section ratio, ,
a direct measure of the contribution of hard two-photon exchange to the elastic
cross section. In the OLYMPUS measurement, 2.01~GeV electron and positron beams
were directed through a hydrogen gas target internal to the DORIS storage ring
at DESY. A toroidal magnetic spectrometer instrumented with drift chambers and
time-of-flight scintillators detected elastically scattered leptons in
coincidence with recoiling protons over a scattering angle range of to . The relative luminosity between the two beam species
was monitored using tracking telescopes of interleaved GEM and MWPC detectors
at , as well as symmetric M{\o}ller/Bhabha calorimeters at
. A total integrated luminosity of 4.5~fb was collected. In
the extraction of , radiative effects were taken into account
using a Monte Carlo generator to simulate the convolutions of internal
bremsstrahlung with experiment-specific conditions such as detector acceptance
and reconstruction efficiency. The resulting values of , presented
here for a wide range of virtual photon polarization ,
are smaller than some hadronic two-photon exchange calculations predict, but
are in reasonable agreement with a subtracted dispersion model and a
phenomenological fit to the form factor data.Comment: 5 pages, 3 figures, 2 table
Search for Doubly-Charged Higgs Boson Production at HERA
A search for the single production of doubly-charged Higgs bosons H^{\pm \pm}
in ep collisions is presented. The signal is searched for via the Higgs decays
into a high mass pair of same charge leptons, one of them being an electron.
The analysis uses up to 118 pb^{-1} of ep data collected by the H1 experiment
at HERA. No evidence for doubly-charged Higgs production is observed and mass
dependent upper limits are derived on the Yukawa couplings h_{el} of the Higgs
boson to an electron-lepton pair. Assuming that the doubly-charged Higgs only
decays into an electron and a muon via a coupling of electromagnetic strength
h_{e \mu} = \sqrt{4 \pi \alpha_{em}} = 0.3, a lower limit of 141 GeV on the
H^{\pm\pm} mass is obtained at the 95% confidence level. For a doubly-charged
Higgs decaying only into an electron and a tau and a coupling h_{e\tau} = 0.3,
masses below 112 GeV are ruled out.Comment: 15 pages, 3 figures, 1 tabl
OLYMPUS: First measurement of the charge-averaged elastic lepton-proton scattering cross section
We report the first measurement of the average of the electron-proton and
positron-proton elastic scattering cross sections. This lepton charge-averaged
cross section is insensitive to the leading effects of hard two-photon
exchange, giving more robust access to the proton's electromagnetic form
factors. The cross section was extracted from data taken by the OLYMPUS
experiment at DESY, in which alternating stored electron and positron beams
were scattered from a windowless gaseous hydrogen target. Elastic scattering
events were identified from the coincident detection of the scattered lepton
and recoil proton in a large-acceptance toroidal spectrometer. The luminosity
was determined from the rates of M{\o}ller, Bhabha and elastic scattering in
forward electromagnetic calorimeters. The data provide some selectivity between
existing form factor global fits and will provide valuable constraints to
future fits.Comment: 6 pages, 3 figures, submitted to PR
Study of Charm Fragmentation into D^{*\pm} Mesons in Deep-Inelastic Scattering at HERA
The process of charm quark fragmentation is studied using meson
production in deep-inelastic scattering as measured by the H1 detector at HERA.
Two different regions of phase space are investigated defined by the presence
or absence of a jet containing the meson in the event. The
parameters of fragmentation functions are extracted for QCD models based on
leading order matrix elements and DGLAP or CCFM evolution of partons together
with string fragmentation and particle decays. Additionally, they are
determined for a next-to-leading order QCD calculation in the fixed flavour
number scheme using the independent fragmentation of charm quarks to
mesons.Comment: 33 pages, submitted to EPJ
Jet production in ep collisions at high Q(2) and determination of alpha(s)
The production of jets is studied in deep-inelastic e(+/-) p scattering at large negative four momentum transfer squared 150 LT Q(2) LT 15000 GeV2 using HERA data taken in 1999-2007, corresponding to an integrated luminosity of 395 pb(-1). Inclusive jet, 2-jet and 3-jet cross sections, normalised to the neutral current deep-inelastic scattering cross sections, are measured as functions of Q(2), jet transverse momentum and proton momentum fraction. The measurements are well described by perturbative QCD calculations at next-to-leading order corrected for hadronisation effects. The strong coupling as determined from these measurement
Introducing SourceForge to the WPI Community
This project introduces SourceForge to the WPI community. SourceForge is a secure, centralized solution for optimizing and managing distributed project development. To substantiate its introduction, a vigorous feasibility study was embarked on. Based on the survey, it was clearly evident that SourceForge should be introduced to the WPI community so that projects could be efficiently managed, instead of using poorly-designed consolidating software. In view of this, clear-cut procedures and videos are produced to guide individuals in the usage of SourceForge.
3D Mobile Game Engine
This project explores the feasibility of a mobile 3D game engine on a smart device. Using OpenGL ES, a graphics library for embedded devices, we have developed Tubetris, a unique and entertaining fully three dimensional puzzle game which runs on a HP iPaq PDA . The game demonstrates the 3D capabilities of mobile devices and that fully 3D applications are indeed possible on mobile devices
Testing the YerPhI Transimpedance Preamplifier with PPC by the T11 PS Beam
We report on the test of the preamplifier, described in [1], by the 3 GeV/c positive particle T11 beam of PS/CERN. We have measured the amplitude and time of flight spectrum, the time resolution and detection efficiency. The preamplifier has shown a stable work and hardness to the chamber discharge. The test results are presented
Modellbasiertes Ressourcenmanagement fuer die Rettungsphase in Erdbebengebieten
Available from TIB Hannover: RN 3221(47) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
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