1,354,207 research outputs found
Measurement of Anti-Deuteron Production and a Search for Heavy Stable Charged Particles at HERA
No full textThe cross section for anti-deuteron photoproduction is measured at HERA at a mean centre-ofmassenergy of Wãp = 200 GeV in the range 0.2 < pT/M < 0.7 an
Measurement of Dijet Cross Sections in ep Interactions with a Leading Neutron at HERA
No full textNon disponibil
Muon Pair Production in e-p Collisions at HERA
No full textCross sections for the production of two isolated muons up to high di-muon masses are measured in ep collisions at HERAwith the H1 detector in a data sample corresponding to an integrated luminosity of 71 pb.1 at a centre of mass energy of ¡Ìs = 319 GeV. The results are in good agreement with Standard Model predictions, the dominant process being photon ̈Cphoton interactions. Additional muons or electrons are searched for in events with two high transverse momentum muons usingthe full data sample corresponding to 114 pb.1, where data at ¡Ìs = 301 GeV and ¡Ìs = 319 GeV are combined. Both thedi-lepton sample and the tri-lepton sample agree well with the predictions
Search for Bosonic Stop Decays in R-Parity Violating Supersymmetry in e^+p Collisions at HERA
No full textA search for scalar top quarks in R-parity violating supersymmetry is performed in e+p collisions at HERA using the H1detector. The data, taken at ãs = 319 GeV and 301 GeV, correspond to an integrated luminosity of 106 pb-1. The resonantproduction of scalar top quarks ̃t in positron quark fusion via an R-parity violating Yukawa coupling λ_ is considered with thesubsequent bosonic stop decay ̃t ̈ ̃bW. The R-parity violating decay of the sbottom quark ̃b ̈d ̄νe and leptonic and hadronicW decays are considered. No evidence for stop production is found in the search for bosonic stop decays nor in a searchfor the direct R-parity violating decay ̃t ̈eq. Mass dependent limits on λ_ are obtained in the framework of the minimalsupersymmetric Standard Model. Stop quarks with masses up to 275 GeV can be excluded at the 95% confidence level for aYukawa coupling of electromagnetic strength
A Direct Search for Stable Magnetic Monopoles Produced in Positron-Proton Collisions at HERA
No full textNon disponibil
Measurement of Dijet Production at Low Q^2 at HERA
No full textTriple di.erential dijet cross sections in e±p interactions are presented in the region of photonvirtualities 2 7 GeV,E. 2 > 5 GeV, and pseudorapidities -2.5 < ç.1, ç.2 < 0. The measurements are made in the ã.p centre-ofmassframe, using an integrated luminosity of 57 pb-1. The data are compared with NLO QCD calculationsand LO Monte Carlo programs with and without a resolved virtual photon contribution. NLO QCDcalculations fail to describe the region of low Q2 and low jet transverse energies, in contrast to a LOMonte Carlo generator which includes direct and resolved photon interactions with both transversely andlongitudinally polarised photons. Initial and .nal state parton showers are tested as a mechanism forincluding higher order QCD e.ects in low ET jet production
Measurement of the Proton Structure Function F_2 at Low Q^2 in QED Compton Scattering at HERA
No full textThe proton structure function F2(x,Q2) is measured in inelastic QED Compton scattering using data collected with the H1detector at HERA. QED Compton events are used to access the kinematic range of very low virtualities of the exchanged photon,Q2, down to 0.5 GeV2, and Bjorken x up to ¡« 0.06, a region which has not been covered previously by inclusive measurementsat HERA. The results are in agreement with the measurements from fixed target lepton–nucleon scattering experiments
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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