A measurement of the integrated luminosity at the ep collider HERA is presented, exploiting the elastic QED Compton process ep→eγp. The electron and the photon are detected in the backward calorimeter of the H1 experiment. The integrated luminosity of the data recorded in 2003 to 2007 is determined with a precision of 2.3 %. The measurement is found to be compatible with the corresponding result obtained using the Bethe–Heitler process.

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 centre-of-mass 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 four-momentum 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 next-to-leading order QCD fit based on all published H1 inclusive cross section data which are used to extract the parton distribution functions of the proton.

Inclusive production of D* mesons in deep-inelastic ep scattering at HERA is studied in the range 5 < Q^2 <100 GeV^2 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 |eta(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^{ccbar} to the proton structure function F_2 is determined. The results are compared to perturbative QCD predictions at next-to-leading order implementing different schemes for the charm mass treatment and with Monte Carlo models based on leading order matrix elements with parton showers.

The diffractive process ep \rightarrow eXY, where Y denotes a proton or its low mass excitation with MY < 1.6 GeV, is studied with the H1 experiment at HERA. The analysis is restricted to the phase space region of the photon virtuality 3 \leq Q2 \leq 1600 GeV2, the square of the four-momentum transfer at the proton vertex |t| < 1.0 GeV2 and the longitudinal momentum fraction of the incident proton carried by the colourless exchange xIP < 0.05. Triple differential cross sections are measured as a function of xIP, Q2 and beta = x/xIP where x is the Bjorken scaling variable. These measurements are made after selecting diffractive events by demanding a large empty rapidity interval separating the final state hadronic systems X and Y . High statistics measurements covering the data taking periods 1999-2000 and 2004-2007 are combined with previously published results in order to provide a single set of diffractive cross sections from the H1 experiment using the large rapidity gap selection method. The combined data represent a factor between three and thirty increase in statistics with respect to the previously published results. The measurements are compared with predictions from NLO QCD calculations based on diffractive parton densities and from a dipole model. The proton vertex factorisation hypothesis is tested.

The cross section for ep → e bb̄X in photoproduction is measured with the H1 detector at theep-collider HERA. The decay channel bb̄ → eeX ′ is selected by identifying the semielectronic decays of the b-quarks. The total production cross section is measured in the kinematic range given by the photon virtuality Q2 ≤ 1 GeV, the inelasticity0.05 ≤ y ≤ 0.65 and the pseudorapidity of the b-quarks|η(b)|, |η(b̄)| ≤ 2. The differential production cross section is measured as a function of the average transverse momentu m of the beauty quarks〈PT (b)〉 down to the threshold. The results are compared to next-to-leading-order QCD predictions. Submitted toEur. Phys. J.C F.D. Aaron, C. Alexa, V. Andreev, S. Backovic, A. Baghdasaryan , S. Baghdasaryan , E. Barrelet , W. Bartel, K. Begzsuren , A. Belousov, P. Belov, J.C. Bizot , V. Boudry, I. Bozovic-Jelisavcic , J. Bracinik, G. Brandt , M. Brinkmann, V. Brisson, D. Britzger, D. Bruncko, A. Bunyatyan, A. Bylinkin, L. Bystritskaya, A.J. Campbell , K.B. Cantun Avila, F. Ceccopieri , K. Cerny, V. Cerny, V. Chekelian, J.G. Contreras , J.A. Coughlan, J. Cvach, J.B. Dainton, K. Daum, B. Delcourt , J. Delvax, E.A. De Wolf, C. Diaconu, M. Dobre, V. Dodonov, A. Dossanov , A. Dubak, G. Eckerlin, S. Egli, A. Eliseev, E. Elsen, L. Favart, A. Fedotov, R. Felst , J. Feltesse , J. Ferencei , D.-J. Fischer , M. Fleischer , A. Fomenko, E. Gabathuler , J. Gayler , S. Ghazaryan , A. Glazov, L. Goerlich, N. Gogitidze, M. Gouzevitch, C. Grab, A. Grebenyuk, T. Greenshaw, G. Grindhammer , S. Habib, D. Haidt, R.C.W. Henderson , E. Hennekemper , H. Henschel , M. Herbst , G. Herrera, M. Hildebrandt , K.H. Hiller, D. Hoffmann, R. Horisberger , T. Hreus, F. Huber, M. Jacquet , X. Janssen , L. Jönsson, A.W. Jung, H. Jung, M. Kapichine, I.R. Kenyon, C. Kiesling, M. Klein, C. Kleinwort, R. Kogler, P. Kostka, M. Krämer, J. Kretzschmar , K. Krüger, M.P.J. Landon , W. Lange, G. Lǎstovǐcka-Medin, P. Laycock, A. Lebedev, V. Lendermann, S. Levonian, K. Lipka, B. List, J. List, B. Lobodzinski , R. Lopez-Fernandez , V. Lubimov, E. Malinovski, H.-U. Martyn, S.J. Maxfield, A. Mehta, A.B. Meyer, H. Meyer, J. Meyer, S. Mikocki, I. Milcewicz-Mika, F. Moreau, A. Morozov, J.V. Morris, K. Müller, Th. Naumann , P.R. Newman , C. Niebuhr , D. Nikitin, G. Nowak, K. Nowak, B. Olivier, J.E. Olsson , D. Ozerov, P. Pahl , V. Palichik, M. Pandurovic, C. Pascaud , G.D. Patel , E. Perez, A. Petrukhin, I. Picuric, H. Pirumov, D. Pitzl, R. Plǎcakyṫe, B. Pokorny, R. Polifka, B. Povh, V. Radescu , N. Raicevic, T. Ravdandorj , P. Reimer , E. Rizvi, P. Robmann , R. Roosen , A. Rostovtsev , M. Rotaru, J.E. Ruiz Tabasco , S. Rusakov , D. Šálek, D.P.C. Sankey , M. Sauter , E. Sauvan, S. Schmitt , L. Schoeffel , A. Scḧoning, H.-C. Schultz-Coulon , F. Sefkow, L.N. Shtarkov, S. Shushkevich , T. Sloan, Y. Soloviev, P. Sopicki , D. South, V. Spaskov, A. Specka, Z. Staykova, M. Steder , B. Stella, G. Stoicea, U. Straumann , T. Sykora, P.D. Thompson , T.H. Tran, D. Traynor, P. Trüol, I. Tsakov, B. Tseepeldorj , J. Turnau, A. Valkárov́a, C. Vallée, P. Van Mechelen , Y. Vazdik, D. Wegener , E. Wünsch, J.Žáček, J. Źalěsák, Z. Zhang, A. Zhokin, R. Žlebč́ık, H. Zohrabyan, and F. Zomer 27 1 I. Physikalisches Institut der RWTH, Aachen, Germany 2 Vinca Institute of Nuclear Sciences, University of Belgrad e, 1100 Belgrade, Serbia 3 School of Physics and Astronomy, University of Birmingham, Birmingham, UK 4 Inter-University Institute for High Energies ULB-VUB, Bru ssels and Universiteit Antwerpen, Antwerpen, Belgium 5 National Institute for Physics and Nuclear Engineering (NI P E) , Bucharest, Romania k 6 STFC, Rutherford Appleton Laboratory, Didcot, Oxfordshire , UK 7 Institute for Nuclear Physics, Cracow, Poland d 8 Institut für Physik, TU Dortmund, Dortmund, Germany a 9 Joint Institute for Nuclear Research, Dubna, Russia 10 CEA, DSM/Irfu, CE-Saclay, Gif-sur-Yvette, France 11 DESY, Hamburg, Germany 1 12 Institut für Experimentalphysik, Universit ät Hamburg, Hamburg, Germany a 13 Max-Planck-Institut f̈ ur Kernphysik, Heidelberg, Germany 14 Physikalisches Institut, Universit ät Heidelberg, Heidelberg, Germany a 15 Kirchhoff-Institut f̈ur Physik, Universiẗ at Heidelberg, Heidelberg, Germany a 16 Institute of Experimental Physics, Slovak Academy of Scien ces, Kǒsice, Slovak Republic e 17 Department of Physics, University of Lancaster, Lancaster , UK 18 Department of Physics, University of Liverpool, Liverpool , UK 19 School of Physics and Astronomy, Queen Mary, University of L ondon, London, UK 20 Physics Department, University of Lund, Lund, Sweden f 21 CPPM, Aix-Marseille Univ, CNRS/IN2P3, 13288 Marseille, Fran ce 22 Departamento de Fisica Aplicada, CINVESTAV, M érida, Yucat́ an, México 23 Departamento de Fisica, CINVESTAV IPN, M éxico City, Ḿexico 24 Institute for Theoretical and Experimental Physics, Mosco w, Russia 25 Lebedev Physical Institute, Moscow, Russia 26 Max-Planck-Institut f̈ ur Physik, M̈unchen, Germany 27 LAL, Universit́e Paris-Sud, CNRS/IN2P3, Orsay, France 28 LLR, Ecole Polytechnique, CNRS/IN2P3, Palaiseau, France 29 LPNHE, Universit́ e Pierre et Marie Curie Paris 6, Universit é Denis Diderot Paris 7, CNRS/IN2P3, Paris, France 30 Faculty of Science, University of Montenegro, Podgorica, M ontenegro 31 Institute of Physics, Academy of Sciences of the Czech Republ ic, Praha, Czech Republic g 32 Faculty of Mathematics and Physics, Charles University, Pra ha, Czech Republic g 33 Dipartimento di Fisica Universit̀ a di Roma Tre and INFN Roma 3, Roma, Italy 34 Institute for Nuclear Research and Nuclear Energy, Sofia, Bu lgaria 35 Institute of Physics and Technology of the Mongolian Academ y of Sciences, Ulaanbaatar, Mongolia 36 Paul Scherrer Institut, Villigen, Switzerland 37 Fachbereich C, Universit ät Wuppertal, Wuppertal, Germany 38 Yerevan Physics Institute, Yerevan, Armenia 39 DESY, Zeuthen, Germany 40 Institut für Teilchenphysik, ETH, Z̈ urich, Switzerland 41 Physik-Institut der Universit ät Zürich, Zürich, Switzerland 42 Also at Rechenzentrum, Universit ät Wuppertal, Wuppertal, Germany 43 Also at IPNL, Universit́ e Claude Bernard Lyon 1, CNRS/IN2P3, Villeurbanne, France 44 Also at CERN, Geneva, Switzerland 45 Also at Faculty of Physics, University of Bucharest, Buchar est, Romania 46 Also at Ulaanbaatar University, Ulaanbaatar, Mongolia 47 Supported by the Initiative and Networking Fund of the Helmho ltz Association (HGF) under the contract VH-NG-401. 48 Absent on leave from NIPNE-HH, Bucharest, Romania 49 Also at Department of Physics, University of Toronto, Toron to, Ontario, Canada M5S 1A7 50 Also at LAPP, Universit́ e de Savoie, CNRS/IN2P3, Annecy-le-Vieux, France 51 Now at Fermi National Accelerator Laboratory, Batavia, Ill inois 60510, USA a Supported by the Bundesministerium f ür Bildung und Forschung, FRG, under contract numbers 05H09GUF, 05H09VHC, 05H09VHF, 05H16PEA 2 b Supported by the UK Science and Technology Facilities Counci l, and formerly by the UK Particle Physics and Astronomy Research Council c Supported by FNRS-FWO-Vlaanderen, IISN-IIKW and IWT and by Interuniversity Attraction Poles Programme, Belgian Science Policy d Partially Supported by Polish Ministry of Science and Highe r Education, grant DPN/N168/DESY/2009 e Supported by VEGA SR grant no. 2/7062/ 27 f Supported by the Swedish Natural Science Research Council g Supported by the Ministry of Education of the Czech Republic u nder the projects LC527, INGO-LA09042 and MSM0021620859 h Supported by the Swiss National Science Foundation i Supported by CONACYT, M éxico, grant 48778-F j Russian Foundation for Basic Research (RFBR), grant no 1329 .2008.2 and Rosatom k Supported by the Romanian National Authority for Scientific Research under the contract PN 09370101 l Partially Supported by Ministry of Science of Montenegro, n o. 05-1/3-3352

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 centre-of-mass energy √ s = 318 GeV where leading protons are detected by dedicated spectrometers. Correlations of systematic uncertainties are taken into account, resulting in an

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 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 next-to-leading order.

Deep-inelastic positron-proton scattering events at low photon virtuality, Q 2, with a forward jet, produced at small angles with respect to the proton beam, are measured with the H1 detector at HERA. A subsample of events with an additional jet in the central region is also studied. For both samples, differential cross sections and normalised distributions are measured as a function of the azimuthal angle difference, Δϕ, between the forward jet and the scattered positron in bins of the rapidity distance, Y, between them. The data are compared to predictions of Monte Carlo generators based on different evolution approaches as well as to next-to-leading order calculations in order to test the sensitivity to QCD evolution mechanisms.

The cross section for \(ep \rightarrow e\, b\bar{b} X\) in photoproduction is measured with the H1 detector at the ep-collider HERA. The decay channel \(b\bar{b} \rightarrow ee X'\) is selected by identifying the semi-electronic decays of the b-quarks. The total production cross section is measured in the kinematic range given by the photon virtuality Q 2≤1 GeV2, the inelasticity 0.05≤y≤0.65 and the pseudorapidity of the b-quarks \(|\eta(b)|, |\eta(\bar{b})|\leq2\). The differential production cross section is measured as a function of the average transverse momentum of the beauty quarks 〈P T (b)〉 down to the threshold. The results are compared to next-to-leading-order QCD predictions.

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^jet > 6 GeV and pseudorapidity -1.0 < eta^jet < 1.5 in the laboratory frame are selected in the kinematic region of photon virtuality Q^2 > 6 GeV^2 and inelasticity variable 0.07 < y < 0.625. Measurements are also made requiring a jet in the Breit frame with E_T^*jet > 6 GeV. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of 189 pb^-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.

A search for first generation scalar and vector leptoquarks produced in ep collisions is performed by the H1 Collaboration at HERA. The full H1 data sample is used in the analysis, corresponding to an integrated luminosity 446 pb^-1. No evidence for the production of leptoquarks is observed in final states with a large transverse momentum electron or with large missing transverse momentum, and constraints on leptoquark models are derived. For leptoquark couplings of electromagnetic strength lambda=0.3, first generation leptoquarks with masses up to 800 GeV are excluded at 95% confidence level.

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 460 GeV. The kinematic range of the measurement covers low absolute four-momentum transfers squared, 1.5 GeV2<Q 2<120 GeV2, 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 =920 GeV and E p =820 GeV. The new measurements are used to test several phenomenological and QCD models applicable in this low Q 2 and low x kinematic domain.

Inclusive production of D ∗ mesons in deep-inelastic ep scattering at HERA is studied in the range 5< Q 2 <100 GeV 2 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^cc̅ to the proton structure function F 2 is determined. The results are compared to perturbative QCD predictions at next-to-leading order implementing different schemes for the charm mass treatment and with Monte Carlo models based on leading order matrix elements with parton showers.

First measurements are presented of the diffractive cross section σep→eXY at centre-of-mass energies √ s of 225 and 252 GeV, together with a precise new measurement at √ s of 319 GeV, using data taken with the H1 detector in the years 2006 and 2007. Together with previous H1 data at √ s of 301 GeV, the measurements are used to extract the diffractive longitudinal structure function F L in the range of photon virtualities 4.0 ≤Q2 ≤ 44.0 GeV2 and fractional proton longitudinal momentum loss 5× 10−4 ≤ xP ≤ a e-mail: daum@mail.desy.de bAlso at Physics Department, National Technical University, Zografou Campus, 15773 Athens, Greece cAlso at Rechenzentrum, Universitat Wuppertal, Wuppertal, Germany dAlso at University of P.J. Safarik, Kosice, Slovak Republic eAlso at CERN, Geneva, Switzerland fAlso at Max-Planck-Institut fur Physik, Munchen, Germany gAlso at Comenius University, Bratislava, Slovak Republic hAlso at Faculty of Physics, University of Bucharest, Bucharest, Romania iAlso at Ulaanbaatar University, Ulaanbaatar, Mongolia jSupported by the Initiative and Networking Fund of the Helmholtz Association (HGF) under the contract VH-NG-401 kAbsent on leave from NIPNE-HH, Bucharest, Romania lOn leave of absence at CERN, Geneva, Switzerland mSupported by the Bundesministerium fur Bildung und Forschung, FRG, under contract numbers 05H09GUF, 05H09VHC, 05H09VHF, 05H16PEA nSupported by the UK Science and Technology Facilities Council, and formerly by the UK Particle Physics and Astronomy Research Council 3× 10−3. The measured F L is compared with leading twist predictions based on diffractive parton densities extracted in NLO QCD fits to previous measurements of diffractive Deep-Inelastic Scattering and with a model which additionally includes a higher twist contribution derived from a colour dipole approach. The ratio of the diffractive cross section induced by longitudinally polarised photons to that for transversely polarised photons is extracted and compared with the analogous quantity for inclusive Deep-Inelastic Scattering. oSupported by FNRS-FWO-Vlaanderen, IISN-IIKW and IWT and by Interuniversity Attraction Poles Programme, Belgian Science Policy pPartially Supported by Polish Ministry of Science and Higher Education, grant DPN/N168/DESY/2009 qSupported by the Deutsche Forschungsgemeinschaft rSupported by VEGA SR grant No. 2/7062/27 sSupported by the Swedish Natural Science Research Council tSupported by the Ministry of Education of the Czech Republic under the projects LC527, INGO-LA09042 and MSM0021620859 uSupported by the Swiss National Science Foundation vSupported by CONACYT, Mexico, grant 48778-F wRussian Foundation for Basic Research (RFBR), grant no 1329.2008.2 xThis project is co-funded by the European Social Fund (75%) and National Resources (25%)–(EPEAEK II)–PYTHAGORAS II ySupported by the Romanian National Authority for Scientific Research under the contract PN 09370101 zPartially Supported by Ministry of Science of Montenegro, No. 051/3-3352

The cross section for the diffractive deep-inelastic scattering process ep -> eXp is measured, with the leading final state proton detected in the H1 Forward Proton Spectrometer. The data sample covers the range x(P) < 0.1 in fractional proton longitudinal momentum loss, 0.1 < vertical bar t vertical bar < 0.7 GeV2 in squared four-momentum transfer at the proton vertex and 4 < Q(2) < 700 GeV2 in photon virtuality. The cross section is measured four-fold differentially in t, x(P), Q2 and beta = x/x(P), where x is the Bjorken scaling variable. The t and x(P) dependences are interpreted in terms of an effective pomeron trajectory and a sub-leading exchange. The data are compared with perturbative QCD predictions at next-to-leading order based on diffractive parton distribution functions previously extracted from complementary measurements of inclusive diffractive deep-inelastic scattering. The ratio of the diffractive to the inclusive ep cross section is studied as a function of Q(2), beta and x(P).

A search for physics beyond the Standard Model in neutral current deep inelastic scattering at high negative four-momentum transfer squared Q(2) is performed in e(+/-)p collisions at HERA. The differential cross section d sigma/dQ(2), measured using the full H1 data sample corresponding to an integrated luminosity of 446 pb(-1), is compared to the Standard Model prediction. No significant deviation is observed. Limits on various models predicting new phenomena at high Q(2) are derived. For general four-fermion eeqq contact interaction models, lower limits on the compositeness scale A are set in the range 3.6 TeV to 7.2 TeV. Leptoquarks with masses M-LQ and couplings lambda are constrained to M-LQ/lambda > 0.41-1.86 TeV and limits on squarks in R-parity violating supersymmetric models are derived. A lower limit on the gravitational scale in 4 + n dimensions of M-S > 0.9 TeV is established for low-scale quantum gravity effects in models with large extra dimensions. For the light quark radius an upper bound of R-q < 0.65 . 10(-18) m is determined. (C) 2011 Elsevier B.V. All rights reserved.

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≤2000 GeV2 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 189 pb−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.

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 \( q\overline q \) 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.