Publications (423)139.71 Total impact
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Article: A-dependence of low-mass muon pair production in 300 GeV/c p and 320 GeV/c $\pi^{-}$ interactions
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ABSTRACT: The A-dependence of inclusive μ+μ− production is measured in the kinematical region 2mμ⩽m(μ+μ−) ⪅1.5 GeV/c2, 0.1≲xF(μ+μ−) ≲0.6, using a 300 GeV/cp beam and a 320 GeV/cπ− beam, on Al, Fe, and U targets. Assuming that the production cross section varies as Aα, we obtain α=0.68±0.03−0.05+0.02 for the beam and α=0.8+-0.02−0.05+0.02 for the the π− beamPhysics Letters B 02/2013; 213(3):395-399. · 3.95 Impact Factor -
Article: A-dependence of the charm production cross section in 320 GeV/c pi- interactions
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ABSTRACT: Using a beam incident on three different target materials Al, Fe, and U, the A-dependence of charm production is studied by measuring the yield of prompt single muons. Parametrizing the charm cross section as σcc(π−A) = σ0Aα the measured α values are α(μ+) = 0.76 ± 0.08 and α(μ−) = 0.83 ± 0.06.Physics Letters B 02/2013; 191(4):456-461. · 3.95 Impact Factor -
Article: Performance of a sampling calorimeter with alternate U and Fe absorbers
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ABSTRACT: A sampling hadronic calorimeter, consisting of a sandwich of scintillator plates and alternate U and Fe absorbers, has been tested in a 135 GeV energy beam. The energy resolution turns out to be significantly improved with respect to the homogeneous configurations in which only U or Fe absorbers are used.Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 02/2013; 248(2-3):326. · 1.21 Impact Factor -
Article: BB inclusive cross-section in 320-GeV $\pi^{-}$-uranium interactions
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ABSTRACT: The inclusive cross section for B production by 320 GeV π− on uranium has been measured, assuming different production models and a variable amount of B0−0 mixing. A comparison of our results with those of the NA10 Collaboration is performed. The J/Ψ inclusive production cross section has also been measured in our experiment and agrees well with existing data, thus confirming the accuracy of our overall normalization.Physics Letters B 02/2013; 231(3):328. · 3.95 Impact Factor -
Article: A muon spectrometer with calorimeter dump used for the beauty search at the CERN Super Proton Synchrotron
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ABSTRACT: A detailed description is given of the WA78 apparatus, which combines a dump calorimeter and a muon spectrometer and is used to measure the cross-section for B production by a high-intensity 320 GeV π− beam. The performance of the various parts of the equipment is discussed. In particular, we consider all the problems related to the calorimetric measurement in high-rate conditions.Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 02/2013; 253(2). · 1.21 Impact Factor -
Article: The production of beauty particles in pi-U interactions at 320 GeV energy
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ABSTRACT: B production in π−-uranium interactions has been observed at 320 GeV beam energy looking at events with three muons in the final state. The cross section is found to be per nucleon (for a linear A-dependence) or per nucleon (assuming A0.75 dependence). An estimate of xF distribution is given.Physics Letters B 02/2013; 187(3-4):431. · 3.95 Impact Factor -
Article: A-dependence of the charm production cross-section in 300 GeV/c proton interactions
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ABSTRACT: The A-dependence of the charm production cross section is determined by measuring the yield of prompt single muons in a beam-dump experiment, using a 300 GeV/c proton beam on Al, Fe, and U targets. Assuming that the production cross section varies as Aα, we obtain α(μ+)=0.79±0.12 and α(μ−)=0.76±0.13 in the kinematical region of the charm.Physics Letters B 02/2013; 206(3):543. · 3.95 Impact Factor -
Article: Experimental study of BB production π-U interactions at 320 GeV energy
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ABSTRACT: A sample of 29 gu+ υ+ 35 υ− υ− coming from B decay have been observed in π-U interactions at 320 GeV energy. The experimental distributions and the total cross section are found to be in good agreement with QCD predictions. The effect of B00 mixing is discussed.Physics Letters B 02/2013; · 3.95 Impact Factor -
Article: Combination and QCD Analysis of Charm Production Cross Section Measurements in Deep-Inelastic ep Scattering at HERA
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ABSTRACT: Measurements of open charm production cross sections in deep-inelastic ep scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross sections sigma_red^{c\bar{c}} for charm production are obtained in the kinematic range of photon virtuality 2.5<Q2<2000 GeV2 and Bjorken scaling variable 0.00003<x<0.05. The combination method accounts for the correlations of the systematic uncertainties among the different data sets. The combined charm data together with the combined inclusive deep-inelastic scattering cross sections from HERA are used as input for a detailed NLO QCD analysis to study the influence of different heavy flavour schemes on the parton distribution functions. The optimal values of the charm mass as a parameter in these different schemes are obtained. The implications on the NLO predictions for W^{\pm} and Z production cross sections at the LHC are investigated. Using the fixed flavour number scheme, the running mass of the charm quark is determined.11/2012; -
Article: Search for squarks in R-parity violating supersymmetry in ep collisions at HERA
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ABSTRACT: A search for squarks in R-parity violating supersymmetry is performed in e ± p collisions at HERA using the H1 detector. The full data sample taken at a centre-of-mass energy Ös=319\sqrt{s}=319GeV is used for the analysis, corresponding to an integrated luminosity of 255pb−1 of e + p and 183pb−1 of e − p collision data. The resonant production of squarks via a Yukawa coupling λ′ is considered, taking into account direct and indirect R-parity violating decay modes. Final states with jets and leptons are investigated. No evidence for squark production is found and mass dependent limits on λ′ are obtained in the framework of the Minimal Supersymmetric Standard Model and in the Minimal Supergravity Model. In the considered part of the parameter space, for a Yukawa coupling of electromagnetic strength λ′=0.3, squarks of all flavours are excluded up to masses of 275GeV at 95% confidence level, with down-type squarks further excluded up to masses of 290GeV.European Physical Journal C 04/2012; 71(3):1-16. · 3.63 Impact Factor -
Article: Inclusive D*± meson and associated dijet production in deep-inelastic scattering at HERA
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ABSTRACT: Inclusive D*± production is measured in deep-inelastic ep scattering at HERA with the H1 detector. In addition, the production of dijets in events with a D*± meson is investigated. The analysis covers values of photon virtuality 2 ≤ Q2 ≤ 100GeV2 and of inelasticity 0.05≤y≤0.7. Differential cross sections are measured as a function of Q2 and x and of various D*± meson and jet observables. Within the experimental and theoretical uncertainties all measured cross sections are found to be adequately described by next-to-leading order (NLO) QCD calculations, based on the photon–gluon fusion process and DGLAP evolution, without the need for an additional resolved component of the photon beyond what is included at NLO. A reasonable description of the data is also achieved by a prediction based on the CCFM evolution of partons involving the kT-unintegrated gluon distribution of the proton.European Physical Journal C 04/2012; 51(2):271-287. · 3.63 Impact Factor -
Article: Measurement of the inclusive e±p scattering cross section at high inelasticity y and of the structure function FL
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ABSTRACT: A measurement is presented of the inclusive neutral current e ± p scattering cross section using data collected by the H1 experiment at HERA during the years 2003 to 2007 with proton beam energies E p of 920, 575, and 460GeV. The kinematic range of the measurement covers low absolute four-momentum transfers squared, 1.5GeV2<Q 2<120GeV2, small values of Bjorken x, 2.9⋅10−5<x<0.01, and extends to high inelasticity up to y=0.85. The structure function F L is measured by combining the new results with previously published H1 data at E p =920GeV and E p =820GeV. The new measurements are used to test several phenomenological and QCD models applicable in this low Q 2 and low x kinematic domain.European Physical Journal C 04/2012; 71(3):1-50. · 3.63 Impact Factor -
Article: Measurement of leading neutron production in deep-inelastic scattering at HERA
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ABSTRACT: The production of leading neutrons, where the neutron carries a large fraction x L of the incoming proton’s longitudinal momentum, is studied in deep-inelastic positron-proton scattering at HERA. The data were taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of 122pb−1. The semi-inclusive cross section is measured in the phase space defined by the photon virtuality 6<Q 2<100GeV2, Bjorken scaling variable 1.5⋅10−4<x<3⋅10−2, longitudinal momentum fraction 0.32<x L <0.95 and neutron transverse momentum p T <0.2GeV. The leading neutron structure function, F2LN(3)(Q2,x,xL)F_{2}^{LN(3)}(Q^{2},x,x_{L}), and the fraction of deep-inelastic scattering events containing a leading neutron are studied as a function of Q 2, x and x L . Assuming that the pion exchange mechanism dominates leading neutron production, the data provide constraints on the shape of the pion structure function.European Physical Journal C 04/2012; 68(3):381-399. · 3.63 Impact Factor -
Article: Three- and four-jet production at low x at HERA
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ABSTRACT: Three- and four-jet production is measured in deep-inelastic ep scattering at low x and Q2 with the H1 detector using an integrated luminosity of 44.2pb-1. Several phase space regions are selected for the three-jet analysis in order to study the underlying parton dynamics from global topologies to the more restrictive regions of forward jets close to the proton direction. The measurements of cross sections for events with at least three jets are compared to fixed order QCD predictions of O(a\texts2){\mathcal{O}}(\alpha_{{\text{s}}}^2) and O(a\texts3){\mathcal{O}}(\alpha_{{\text{s}}}^3) and with Monte Carlo simulation programs where higher order effects are approximated by parton showers. A good overall description is provided by the O(a\texts3){\mathcal{O}}(\alpha_{{\text{s}}}^3) calculation. Too few events are predicted at the lowest x∼10-4, especially for topologies with two forward jets. This hints to large contributions at low x from initial state radiation of gluons close to the proton direction and unordered in transverse momentum. The Monte Carlo program in which gluon radiation is generated by the colour dipole model gives a good description of both the three- and the four-jet data in absolute normalisation and shape.European Physical Journal C 04/2012; 54(3):389-409. · 3.63 Impact Factor -
Article: Measurement of charm and beauty jets in deep inelastic scattering at HERA
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ABSTRACT: Measurements of cross sections for events with charm and beauty jets in deep inelastic scattering at HERA are presented. Events with jets of transverse energy $E_{T}^{\mathrm{jet}}>6$E_{T}^{\mathrm{jet}}>6GeV and pseudorapidity −1.0<η jet<1.5 in the laboratory frame are selected in the kinematic region of photon virtuality Q 2>6GeV2 and inelasticity variable 0.07<y<0.625. Measurements are also made requiring a jet in the Breit frame with $E_{T}^{*{\mathrm{jet}}}>6$E_{T}^{*{\mathrm{jet}}}>6GeV. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of 189pb−1. The numbers of charm and beauty jets are determined using variables reconstructed using the H1 vertex detector with which the impact parameters of the tracks to the primary vertex and the position of secondary vertices are measured. The measurements are compared with QCD predictions and with previous measurements where heavy flavours are identified using muons.European Physical Journal C 04/2012; 71(1):1-21. · 3.63 Impact Factor -
Article: Jet production in ep collisions at high Q2 and determination of αs
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ABSTRACT: The production of jets is studied in deep-inelastic e ± p scattering at large negative four momentum transfer squared 150<Q 2<15000GeV2 using HERA data taken in 1999–2007, corresponding to an integrated luminosity of 395pb−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 measurements is as(MZ)=0.1168±0.0007(exp.)+0.0046-0.0030(th.)±0.0016\alpha_{s}(M_{Z})=0.1168\pm0.0007\,\mathrm{(exp.)}{}^{+0.0046}_{-0.0030}\,\mathrm{(th.)}\pm 0.0016 (PDF).European Physical Journal C 04/2012; 65(3):363-383. · 3.63 Impact Factor -
Article: Diffractive electroproduction of ρ and ϕ mesons at HERA
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ABSTRACT: Diffractive electroproduction of ρ and ϕ mesons is measured at HERA with the H1 detector in the elastic and proton dissociative channels. The data correspond to an integrated luminosity of 51 pb−1. About 10500 ρ and 2000 φ events are analysed in the kinematic range of squared photon virtuality 2.5 ≤ Q 2 ≤ 60 GeV2, photon-proton centre of mass energy 35 ≤ W ≤ 180 GeV and squared four-momentum transfer to the proton |t| ≤ 3 GeV2. The total, longitudinal and transverse cross sections are measured as a function of Q 2, W and |t|. The measurements show a transition to a dominantly “hard” behaviour, typical of high gluon densities and small q[`(q)] q\overline q dipoles, for Q 2 larger than 10 to 20 GeV2. They support flavour independence of the diffractive exchange, expressed in terms of the scaling variable (Q 2+M 2 V )/4, and proton vertex factorisation. The spin density matrix elements are measured as a function of kinematic variables. The ratio of the longitudinal to transverse cross sections, the ratio of the helicity amplitudes and their relative phases are extracted. Several of these measurements have not been performed before and bring new information on the dynamics of diffraction in a QCD framework. The measurements are discussed in the context of models using generalised parton distributions or universal dipole cross sections. KeywordsLepton-Nucleon ScatteringJournal of High Energy Physics 04/2012; 2010(5):1-111. · 5.83 Impact Factor -
Article: Strangeness production at low Q2 in deep-inelastic ep scattering at HERA
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ABSTRACT: The production of neutral strange hadrons is investigated using deep-inelastic scattering events measured with the H1 detector at HERA. The measurements are made in the phase space defined by the negative four-momentum transfer squared of the photon 2<Q 2<100 GeV2 and the inelasticity 0.1<y<0.6. The K s 0 and \varLambda([`\varLambda])\varLambda(\bar{\varLambda}) production cross sections and their ratios are determined. K s 0 production is compared to the production of charged particles in the same region of phase space. The Λ– [`\varLambda]\bar{\varLambda} asymmetry is also measured and found to be consistent with zero. Predictions of leading order Monte Carlo programs are compared to the data.European Physical Journal C 04/2012; 61(2):185-205. · 3.63 Impact Factor -
Article: Prompt photons in photoproduction at HERA
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ABSTRACT: The production of prompt photons is measured in the photoproduction regime of electron–proton scattering at HERA. The analysis is based on a data sample corresponding to a total integrated luminosity of 340pb−1 collected by the H1 experiment. Cross sections are measured for photons with transverse momentum and pseudorapidity in the range 6 < ETg < 156European Physical Journal C 04/2012; 66(1):17-33. · 3.63 Impact Factor -
Article: Measurement of the charm and beauty structure functions using the H1 vertex detector at HERA
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ABSTRACT: Inclusive charm and beauty cross sections are measured in e − p and e + p neutral current collisions at HERA in the kinematic region of photon virtuality 5≤Q 2≤2000GeV2 and Bjorken scaling variable 0.0002≤x≤0.05. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of 189pb−1. The numbers of charm and beauty events are determined using variables reconstructed by the H1 vertex detector including the impact parameter of tracks to the primary vertex and the position of the secondary vertex. The measurements are combined with previous data and compared to QCD predictions.European Physical Journal C 04/2012; 65(1):89-109. · 3.63 Impact Factor
Top co-authors
Top Journals
Institutions
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2006–2012
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Comenius University in Bratislava
Bratislava, Bratislavsky Kraj, Slovakia -
Università Degli Studi Roma Tre
- Department of Mathematics and Physics
Roma, Latium, Italy
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2007
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University of Antwerp
Antwerpen, VLG, Belgium
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2005
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University of Birmingham
- School of Physics and Astronomy
Birmingham, ENG, United Kingdom
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1996
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Humboldt-Universität zu Berlin
Berlin, Land Berlin, Germany
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1994–1995
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Yerevan Physics Institute
Yerevan, K'aghak' Yerevan, Armenia
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1988
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Carnegie Mellon University
Pittsburgh, PA, USA
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1987
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University of Leicester
Leicester, ENG, United Kingdom
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