Publications (568)1443.13 Total impact
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ABSTRACT: A first measurement is presented of exclusive photoproduction of \(\rho ^0\) mesons associated with leading neutrons at HERA. The data were taken with the H1 detector in the years 2006 and 2007 at a centreofmass energy of \(\sqrt{s}=319\) GeV and correspond to an integrated luminosity of 1.16 pb\(^{1}\). The \(\rho ^0\) mesons with transverse momenta \(p_T<1\) GeV are reconstructed from their decays to charged pions, while leading neutrons carrying a large fraction of the incoming proton momentum, \(x_L>0.35\), are detected in the Forward Neutron Calorimeter. The phase space of the measurement is defined by the photon virtuality \(Q^2 < 2\) GeV\(^2\), the total energy of the photon–proton system \(20 < W_{\gamma p}< 100\) GeV and the polar angle of the leading neutron \(\theta _n < 0.75\) mrad. The cross section of the reaction \(\gamma p \rightarrow \rho ^0 n \pi ^+\) is measured as a function of several variables. The data are interpreted in terms of a double peripheral process, involving pion exchange at the proton vertex followed by elastic photoproduction of a \(\rho ^0\) meson on the virtual pion. In the framework of onepionexchange dominance the elastic cross section of photonpion scattering, \(\sigma ^\mathrm{el}(\gamma \pi ^+ \rightarrow \rho ^0\pi ^+)\), is extracted. The value of this cross section indicates significant absorptive corrections for the exclusive reaction \(\gamma p \rightarrow \rho ^0 n \pi ^+\).  [Show abstract] [Hide abstract]
ABSTRACT: A combination is presented of all inclusive deep inelastic cross sections previously published by the H1 and ZEUS collaborations at HERA for neutral and charged current (Formula presented.) scattering for zero beam polarisation. The data were taken at proton beam energies of 920, 820, 575 and 460 GeV and an electron beam energy of 27.5 GeV. The data correspond to an integrated luminosity of about 1 fb(Formula presented.) and span six orders of magnitude in negative fourmomentumtransfer squared, (Formula presented.), and Bjorken x. The correlations of the systematic uncertainties were evaluated and taken into account for the combination. The combined cross sections were input to QCD analyses at leading order, nexttoleading order and at nexttonexttoleading order, providing a new set of parton distribution functions, called HERAPDF2.0. In addition to the experimental uncertainties, model and parameterisation uncertainties were assessed for these parton distribution functions. Variants of HERAPDF2.0 with an alternative gluon parameterisation, HERAPDF2.0AG, and using fixedflavournumber schemes, HERAPDF2.0FF, are presented. The analysis was extended by including HERA data on charm and jet production, resulting in the variant HERAPDF2.0Jets. The inclusion of jetproduction cross sections made a simultaneous determination of these parton distributions and the strong coupling constant possible, resulting in (Formula presented.). An extraction of (Formula presented.) and results on electroweak unification and scaling violations are also presented. 
Article: Combination of differential D∗± crosssection measurements in deepinelastic ep scattering at HERA
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ABSTRACT: H1 and ZEUS have published singledifferential cross sections for inclusive D ∗±meson production in deepinelastic ep scattering at HERA from their respective final data sets. These cross sections are combined in the common visible phasespace region of photon virtuality Q 2> 5 GeV2, electron inelasticity 0.02 < y < 0.7 and the D ∗± meson’s transverse momentum p T(D ∗) > 1.5 GeV and pseudorapidity η(D ∗) < 1.5. The combination procedure takes into account all correlations, yielding significantly reduced experimental uncertainties. Doubledifferential cross sections d2σ/dQ 2dy are combined with earlier D ∗± data, extending the kinematic range down to Q 2> 1.5 GeV2. Perturbative nexttoleadingorder QCD predictions are compared to the results.  [Show abstract] [Hide abstract]
ABSTRACT: The cross section of the diffractive process e+p → e+Xp is measured at a centreofmass energy of 318 GeV, where the system X contains at least two jets and the leading final state proton p is detected in the H1 Very Forward Proton Spectrometer. The measurement is performed in photoproduction with photon virtualities Q2< 2 GeV2 and in deepinelastic scattering with 4 GeV2< Q2< 80 GeV2. The results are compared to next toleading order QCD calculations based on diffractive parton distribution functions as extracted from measurements of inclusive cross sections in diffractive deepinelastic scattering.  [Show abstract] [Hide abstract]
ABSTRACT: Inclusive jet, dijet and trijet differential cross sections are measured in neutral current deepinelastic scattering for exchanged boson virtualities using the H1 detector at HERA. The data were taken in the years 2003 to 2007 and correspond to an integrated luminosity of. Double differential Jet cross sections are obtained using a regularised unfolding procedure. They are presented as a function of and the transverse momentum of the jet, and as a function of and the proton’s longitudinal momentum fraction, carried by the parton participating in the hard interaction. In addition normalised double differential jet cross sections are measured as the ratio of the jet cross sections to the inclusive neutral current cross sections in the respective bins of the jet measurements. Compared to earlier work, the measurements benefit from an improved reconstruction and calibration of the hadronic final state. The cross sections are compared to perturbative QCD calculations in nexttoleading order and are used to determine the running coupling and the value of the strong coupling constant as.  [Show abstract] [Hide abstract]
ABSTRACT: Measurements of normalised cross sections for the production of photons and neutrons at very small angles with respect to the proton beam direction in deepinelastic ep scattering at HERA are presented as a function of the Feynman variable xF and of the centreofmass energy of the virtual photonproton system W. The data are taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of 131 pb1. The measurement is restricted to photons and neutrons in the pseudorapidity range η > 7.9 and covers the range of negative four momentum transfer squared at the positron vertex 6 < Q2 < 100 GeV2, of inelasticity 0.05 < y < 0.6 and of 70 < W < 245 GeV. To test the Feynman scaling hypothesis the W dependence of the xF dependent cross sections is investigated. Predictions of deepinelastic scattering models and of models for hadronic interactions of high energy cosmic rays are compared to the measured cross sections.  [Show abstract] [Hide abstract]
ABSTRACT: Inclusive ep double differential cross sections for neutral current deep inelastic scattering are measured with the H1 detector at HERA. The data were taken with a lepton beam energy of 27.6 GeV and two proton beam energies of Ep = 460 and 575 GeV corresponding to centreofmass energies of 225 and 252 GeV, respectively. The measurements cover the region of 6.5 × 104 ≤ x ≤ 0.65 for 35 ≤ Q2 ≤ 800 GeV2 up to y = 0.85. The measurements are used together with previously published H1 data at Ep = 920 GeV and lower Q2 data at Ep = 460, 575 and 920 GeV to extract the longitudinal proton structure function FL in the region 1.5 ≤ Q2 ≤ 800 GeV2. 
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ABSTRACT: A search for excited electrons is performed using the full e±p data sample collected by the H1 experiment at HERA, corresponding to a total luminosity of 475 pb−1. The electroweak decays of excited electrons e∗→eγ, e∗→eZ and e∗→νW with subsequent hadronic or leptonic decays of the W and Z bosons are considered. No evidence for excited electron production is found. Mass dependent exclusion limits on e∗ production cross sections and on the ratio f/Λ of the coupling to the compositeness scale are derived within gauge mediated models. These limits extend the excluded region compared to previous excited electron searches. The e∗ production via contact interactions is also addressed for the first time in ep collisions.  [Show abstract] [Hide abstract]
ABSTRACT: A search for scalar and vector leptoquarks coupling to first generation fermions is performed using the e+p and e−p scattering data collected by the H1 experiment between 1994 and 2000. The data correspond to a total integrated luminosity of 117 pb−1. No evidence for the direct or indirect production of such particles is found in data samples with a large transverse momentum final state electron or with large missing transverse momentum. Constraints on leptoquark models are established. For leptoquark couplings of electromagnetic strength, leptoquarks with masses up to 275–325 GeV are ruled out at 95% confidence level. These limits improve and supercede earlier H1 limits based on subsamples of the data used here. 
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ABSTRACT: Cross sections for elastic and protondissociative photoproduction of J/psi mesons are measured with the H1 detector in positronproton collisions at HERA. The data were collected at $ep$ centreofmass energies sqrt{s} approx 318 GeV and sqrt{s} approx 225 GeV, corresponding to integrated luminosities of L = 130 pb^{1} and L = 10.8 pb^{1}, respectively. The cross sections are measured as a function of the photonproton centreofmass energy in the range 25< Wgp < 110 GeV. Differential cross sections $\mathrm{d}\sigma / \mathrm{d}t$, where $t$ is the squared fourmomentum transfer at the proton vertex, are measured in the range $t < 1.2 \, \gevsq$ for the elastic process and $t < 8 \, \gevsq$ for proton dissociation. The results are compared to other measurements. The $\Wgp$ and $t$dependences are parametrised using phenomenological fits.  [Show abstract] [Hide abstract]
ABSTRACT: Charged particle production in deepinelastic ep scattering is measured with the H1 detector at HERA. The kinematic range of the analysis covers low photon virtualities, 5 < Q^2 < 100 GeV^2, and small values of Bjorkenx, 10^{4} < x < 10^{2}. The analysis is performed in the hadronic centreofmass system. The charged particle densities are measured as a function of pseudorapidity (eta^*) and transverse momentum (p_T^*) in the range 0< \eta^* < 5 and 0< p_T^* < 10$ GeV differentially in x and Q^2. The data are compared to predictions from different Monte Carlo generators implementing various options for hadronisation and parton evolutions.  [Show abstract] [Hide abstract]
ABSTRACT: Measurements of open charm production cross sections in deepinelastic ep scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross sections \(\sigma_{\rm red}^{c\bar{c}}\) for charm production are obtained in the kinematic range of photon virtuality 2.5≤Q 2≤2000 GeV2 and Bjorken scaling variable 3⋅10−5≤x≤5⋅10−2. 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 deepinelastic 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 ± 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. 
Dataset: desy06110

Dataset: desy06110
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ABSTRACT: Inclusive production of D ∗ mesons in deepinelastic ep scattering at HERA is studied in the range 5<Q 2<100 GeV2 of the photon virtuality and 0.02<y<0.7 of the inelasticity of the scattering process. The observed phase space for the D ∗ meson is p T (D ∗)>1.25 GeV and η(D ∗)<1.8. The data sample corresponds to an integrated luminosity of 348 pb−1 collected with the H1 detector. Single and double differential cross sections are measured and the charm contribution \({F_{2}^{c\bar{c}}}\) to the proton structure function F 2 is determined. The results are compared to perturbative QCD predictions at nexttoleading order implementing different schemes for the charm mass treatment and with Monte Carlo models based on leading order matrix elements with parton showers.  [Show abstract] [Hide abstract]
ABSTRACT: A combination of the inclusive diffractive cross section measurements made by the H1 and ZEUS Collaborations at HERA is presented. The analysis uses samples of diffractive deep inelastic ep scattering data at a centreofmass energy sqrt(s) = 318 GeV where leading protons are detected by dedicated spectrometers. Correlations of systematic uncertainties are taken into account, resulting in an improved precision of the cross section measurement which reaches 6% for the most precise points. The combined data cover the range 2.5 < Q2 < 200 GeV2 in photon virtuality, 0.00035 < xIP < 0.09 in proton fractional momentum loss, 0.09 < t < 0.55 GeV2 in squared fourmomentum transfer at the proton vertex and 0.0018 < beta < 0.816 in beta = x/xIP, where x is the Bjorken scaling variable. 
Article: Measurement of beauty and charm photoproduction using semimuonic decays in dijet events at HERA
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ABSTRACT: Measurements of cross sections for beauty and charm events with dijets and a muon in the photoproduction regime at HERA are presented. The data were collected with the H1 detector and correspond to an integrated luminosity of 179 pb−1. Events with dijets of transverse momentum \(P_{T}^{\mathrm{jet}1}> 7\ \mbox{GeV}\) and \(P_{T}^{\mathrm{jet}2}> 6\ \mbox{GeV}\) in the pseudorapidity range −1.5<η jet<2.5 in the laboratory frame are selected in the kinematic region of photon virtuality Q 2<2.5 GeV2 and inelasticity 0.2<y<0.8. One of the two selected jets must be associated to a muon with \(P_{T}^{\mu} > 2.5\ \mbox{GeV}\) in the pseudorapidity range −1.3<η μ <1.5. The fractions of beauty and charm events are determined using the impact parameters of the muon tracks with respect to the primary vertex and their transverse momentum relative to the axis of the associated jet. Both variables are reconstructed using the H1 vertex detector. The measurements are in agreement with QCD predictions at leading and nexttoleading order. 
Article: Inclusive Deep Inelastic Scattering at High Q2 with LongitudinallyPolarised Lepton Beams at HERA
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ABSTRACT: Inclusive e ± p single and double differential cross sections for neutral and charged current deep inelastic scattering processes are measured with the H1 detector at HERA. The data were taken at a centreofmass energy of \( \sqrt {s} = {319} \) GeV with a total integrated luminosity of 333.7 pb−1 shared between two lepton beam charges and two longitudinal lepton polarisation modes. The differential cross sections are measured in the range of negative fourmomentum transfer squared, Q 2, between 60 and 50 000 GeV2, and Bjorken x between 0.0008 and 0.65. The measurements are combined with earlier published unpolarised H1 data to improve statistical precision and used to determine the structure function \( xF_{3}^{{\gamma Z}} \). Ameasurementoftheneutralcurrentparityviolating structure function \( F_{2}^{{\gamma Z}} \) is presented for the first time. The polarisation dependence of the charged current total cross section is also measured. The new measurements are well described by a nexttoleading order QCD fit based on all published H1 inclusive cross section data which are used to extract the parton distribution functions of the proton.
Publication Stats
9k  Citations  
1,443.13  Total Impact Points  
Top Journals
 Physics Letters B (124)
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Institutions

19822015

Max Planck Institute for Physics
München, Bavaria, Germany 
Laboratoire de l'accélérateur linéaire
Orsay, ÎledeFrance, France


19752009

University of Hamburg
 Institut für Experimentalphysik
Hamburg, Hamburg, Germany


2008

Lund University
 Department of Theoretical Physics
Lund, Skane, Sweden


19782007

Max Planck Institute for Astrophysics
Arching, Bavaria, Germany


2005

University of Birmingham
 School of Physics and Astronomy
Birmingham, ENG, United Kingdom


2002

Institut des Systèmes Complexes, Paris ÎledeFrance
Lutetia Parisorum, ÎledeFrance, France


19921997

HumboldtUniversität zu Berlin
Berlín, Berlin, Germany


1994

Bergische Universität Wuppertal
Wuppertal, North RhineWestphalia, Germany 
AixMarseille Université
Marsiglia, ProvenceAlpesCôte d'Azur, France


1993

ChristianAlbrechtsUniversität zu Kiel
Kiel, SchleswigHolstein, Germany


19871992

University of Glasgow
Glasgow, Scotland, United Kingdom


19901991

Stanford University
 Stanford Linear Accelerator Center
Palo Alto, CA, United States


19891990

Indiana University Bloomington
Bloomington, Indiana, United States


1985

INFN  Istituto Nazionale di Fisica Nucleare
Frascati, Latium, Italy


19821983

Karlsruhe Institute of Technology
Carlsruhe, BadenWürttemberg, Germany


19731979

Deutsches ElektronenSynchrotron
Hamburg, Hamburg, Germany
