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1.	Adloff, C, et al. (författare) Measurement of dijet cross sections in photoproduction at HERA 2002 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 25:1, s. 13-23 Tidskriftsartikel (refereegranskat)abstract Dijet cross sections as functions of several jet observables are measured in photoproduction using the HI detector at HERA. The data sample comprises e(+)p data with an integrated luminosity of 319 pb(-1). Jets are selected using the inclusive k(perpendicular to) algorithm with a minimum transverse energy of 25 GeV for the leading jet. The phase space covers longitudinal proton momentum fraction x(p) and photon longitudinal momentum fraction x(gamma) in the ranges 0.05 < x(p) < 0.6 and 0.1 < x(gamma) < 1. The predict ions of next-to-leading order perturbative QCD, including recent photon and proton parton densities, are found to be compatible with the data in a wide kinematical range.
2.	Aktas, A, et al. (författare) A general search for new phenomena in ep scattering at HERA 2004 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 602:1-2, s. 14-30 Tidskriftsartikel (refereegranskat)abstract A model-independent search for deviations from the Standard Model prediction is performed in e(+) p and e(-) p collisions at HERA using H1 data corresponding to an integrated luminosity of 117 pb(-1). For the first time all event topologies involving isolated electrons, photons, muons, neutrinos and jets with high transverse momenta are investigated in a single analysis. Events are assigned to exclusive classes according to their final state. A statistical algorithm is developed to search for deviations from the Standard Model in the distributions of the scalar sum of transverse momenta or invariant mass of final state particles and to quantify their significance. A good agreement with the Standard Model prediction is observed in most of the event classes. The most significant deviation is found for a topology containing an isolated muon, missing transverse momentum and a jet, consistent with a previously reported observation.
3.	Aktas, A, et al. (författare) Evidence for a narrow anti-charmed baryon state 2004 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 588:1-2, s. 17-28 Tidskriftsartikel (refereegranskat)abstract A narrow resonance in D(-)p and D(+)(p) over bar invariant mass combinations is observed in inelastic electron-proton collisions at centre-of-mass energies of 300 GeV and 320 GeV at HERA. The resonance has a mass of 3099 +/- 3(stat.) +/- 5(syst.) MeV and a measured Gaussian width of 12 +/- 3(stat.) MeV, compatible with the experimental resolution. The resonance is interpreted as an anti-charmed baryon with a minimal constituent quark composition of uudd (c) over bar, together with the charge conjugate. (C) 2004 Elsevier B.V. All rights reserved.
4.	Aktas, A, et al. (författare) Measurement of anti-deuteron photoproduction and a search for heavy stable charged particles at HERA 2004 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 36:4, s. 413-423 Tidskriftsartikel (refereegranskat)abstract The cross section for anti-deuteron photoproduction is measured at HERA at a mean centre-of-mass energy of W-gammap=200 GeV in the range 0.2 < p(T)/M < 0.7 and y < 0.4, where M, p(T) and y are the mass, transverse momentum and rapidity of the anti-deuteron in the HERA laboratory frame, respectively. The numbers of anti-deuterons per event are found to be similar in photoproduction to those in central proton-proton collisions at the CERN ISR but much lower than those in central Au-Au collisions at RHIC. The coalescence parameter B-2, which characterizes the likelihood of anti-deuteron production, is measured in photoproduction to be 0.010+/-0.002+/-0.001, which is much higher than in Au-Au collisions at a similar nucleon-nucleon centre-of-mass energy. No significant production of particles heavier than deuterons is observed and upper limits are set on the photoproduction cross sections for such particles.
5.	Aktas, A, et al. (författare) Measurement of dijet production at low Q(2) at HERA 2004 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 37:2, s. 141-159 Tidskriftsartikel (refereegranskat)abstract Triple differential dijet cross sections in e(+/-)p interactions are presented in the region of photon virtualities 2 < Q(2) < 80 GeV2, inelasticities 0.1 < y < 0.85, jet transverse energies E(T1) > 7GeV, E(T2) > 5 GeV, and pseudorapidities - 2.5 < η(1), η(2) < 0. The measurements are made in the gamma*p centre-of-mass frame, using an integrated luminosity of 57 pb(-1). The data are compared with NLO QCD calculations and LO Monte Carlo programs with and without a resolved virtual photon contribution. NLO QCD calculations fail to describe the region of low Q(2) and low jet transverse energies, in contrast to a LO Monte Carlo generator which includes direct and resolved photon interactions with both transversely and longitudinally polarised photons. Initial and final state parton showers are tested as a mechanism for including higher order QCD effects in low E-T jet production.
6.	Aktas, A, et al. (författare) Measurement of the proton structure function F-2 at low Q(2) in QED Compton scattering at HERA 2004 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 598:3-4, s. 159-171 Tidskriftsartikel (refereegranskat)abstract The proton structure function F-2(x, Q(2)) is measured in inelastic QED Compton scattering using data collected with the H1 detector at HERA. QED Compton events are used to access the kinematic range of very low virtualities of the exchanged photon, Q(2), down to 0.5 GeV2, and Bjorken x up to similar to 0.06, a region which has not been covered previously by inclusive measurements at HERA. The results are in agreement with the measurements from fixed target lepton-nucleon scattering experiments. (C) 2004 Published by Elsevier B.V.
7.	Aktas, A, et al. (författare) Muon pair production in ep collisions at HERA 2004 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 583:1-2, s. 28-40 Tidskriftsartikel (refereegranskat)abstract Cross sections for the production of two isolated muons up to high di-muon masses are measured in ep collisions at HERA with the H1 detector in a data sample corresponding to an integrated luminosity of 71 pb(-1) at a centre of mass energy of roots = 319 GeV. The results are in good agreement with Standard Model predictions, the dominant process being photon-photon interactions. Additional muons or electrons are searched for in events with two high transverse momentum muons using the full data sample corresponding to 114 pb(-1), where data at roots = 301 GeV and roots = 319 GeV are combined. Both the di-lepton sample and the tri-lepton sample agree Well with the predictions. (C) 2004 Published by Elsevier B.V.
8.	Aktas, A, et al. (författare) Search for bosonic stop decays in R-parity violating supersymmetry in e(+)p collisions at HERA 2004 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 599:3-4, s. 159-172 Tidskriftsartikel (refereegranskat)abstract A search for scalar top quarks in R-parity violating supersymmetry is performed in e(+)p collisions at HERA using the H1 detector. The data, taken at roots = 319 GeV and 301 GeV, correspond to an integrated luminosity of 106 pb(-1). The resonant production of scalar top quarks t in positron quark fusion via an R-parity violating Yukawa coupling lambda' is considered with the subsequent bosonic stop decay t --> BW. The R-parity violating decay of the sbottom quark b --> dv(e) and leptonic and hadronic W decays are considered. No evidence for stop production is found in the search for bosonic stop decays nor in a search for the direct R-parity violating decay t --> eq. Mass dependent limits on lambda' are obtained in the framework of the minimal supersymmetric Standard Model. Stop quarks with masses up to 275 GeV can be excluded at the 95% confidence level for a Yukawa coupling of electromagnetic strength. (C) 2004 Elsevier B.V. All rights reserved.
9.	Adloff, C, et al. (författare) A measurement of the t dependence of the helicity structure of diffractive rho meson electroproduction at HERA 2002 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 539:1-2, s. 25-39 Tidskriftsartikel (refereegranskat)abstract The helicity structure of the diffractive electroproduction of rho mesons, e + p --> e + rho + Y, is studied in a previously unexplored region of large four-momentum transfer squared at the proton vertex, t: 0 < t' < 3 GeV2, where t' = - min. The data used are collected with the HI detector at HERA in the kinematic domain 2.5 < Q(2) < 60 GeV2, 40 < W < 120 GeV No t dependence of the r(00)(04) spin density matrix element is found. A significant t dependent helicity non-conservation from the virtual photon to the rho meson is observed for the spin density matrix element combinations r(00)(5) + 2r(11)(5) and r(00)(1) + 2r(11)(1). These t dependences are consistently described by a perturbative QCD model based on the exchange of two gluons.
10.	Adloff, C, et al. (författare) Energy flow and rapidity gaps between jets in photoproduction at HERA 2002 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 24:4, s. 517-527 Tidskriftsartikel (refereegranskat)abstract Dijet events in photon-proton collisions in which there is a large pseudorapidity separation, Deltaeta > 2.5 between the two highest E-T jets are studied with the H1 detector at HERA. The inclusive dijet cross sections are measured as functions of the longitudinal momentum fractions of the proton and photon which participate in the production of the jets, x(p)(jets) and x(gamma)(jets) respectively, Deltaeta, the pseudorapidity P separation between the two highest E-T jets, and E-T(gap), the total summed transverse energy between the jets. Rapidity gap events are defined as events in which E-T(gap) is less than E-T(cut), for E-T(cut) varied between jets 0.5 and 2.0 GeV. The fraction of dijet events with a rapidity gap is measured differentially in Deltaeta, x(p)(jets) and x(gamma)(jets). An excess of events with rapidity gaps at low values of E-T(cut) is observed above the expectation from standard photoproduction processes. This excess can be explained by the exchange of a strongly interacting colour singlet object between the jets.
11.	Adloff, C, et al. (författare) Inelastic leptoproduction of J/psi mesons at HERA 2002 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 25:1, s. 41-53 Tidskriftsartikel (refereegranskat)abstract The leptoproduction of J/psi mesons is studied in inelastic reactions for four momentorri transfers 2 < Q(2) < 100GeV(2). The data were taken with the H1 detector at the electron proton collider HERA and correspond to an integrated luminosity of 77 pb(-1). Single differential and double differential cross sections are measured with increased precision compared with previous analyses. New leading order calculations within the non-relativistic QCD factorisation approach including colour octet and colour singlet contributions are compared with the data and are found to give a reasonable description of most distributions. An exception is the shape of the distribution in the J/psi fractional energy. z, which deviates significantly from that of the data. Comparisons with photoproduction are made and the polarisation of the produced J/psi meson is analysed.
12.	Adloff, C, et al. (författare) Measurement of D(+/-) meson production and F-2(c) in deep-inelastic scattering at HERA 2002 Ingår i:* Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 528:3-4, s. 199-214 Tidskriftsartikel (refereegranskat)abstract The inclusive production of D+/-(2010) mesons in deep-inelastic scattering is studied with the HI detector at HERA. In the kinematic region 1 < Q(2) < 100 GeV2 and 0.05 < y < 0.7 an e(+) p cross section for inclusive D+/- meson production of 8.50 +/- 0.42(stat.)(-100)(+1.21)(syst.) nb is measured in the visible range p(tD) > 1.5 GeV and eta(D) < 1.5. Single and double differential inclusive D*+/- meson cross sections are compared to perturbative QCD calculations in two different evolution schemes, The charm contribution to the proton structure, F-c(2)(x, Q(2)), is determined by extrapolating the visible charm cross section to the full phase space. This contribution is found to rise from about 10% at Q(2) = 1.5 GeV2 to more than 25% at Q(2) = 60 GeV2 corresponding to x values ranging from 5 x 10(-5) to 3 x 10(-3). (C) 2002 Elsevier Science B.V. All rights reserved.
13.	Adloff, C, et al. (författare) Measurement of dijet electroproduction at small jet separation 2002 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 24:1, s. 33-41 Tidskriftsartikel (refereegranskat)abstract Deep-inelastic scattering data in the range 150 < Q(2) < 35000 GeV2 are used to investigate the minimum jet separation necessary to allow accurate description of the rate of dijet production using next-to-leading order perturbative QCD calculations. The required jet separation is found to be small, allowing about 1/3 of DIS data to be classified as dijet, as opposed to approximately 1/10 with more typical jet analyses. A number of precision measurements made using this dijet sample are well described by the calculations. The data are also described by the combination of leading order matrix elements and parton showers, as implemented in the QCD based Monte Carlo model RAPGAP.
14.	Adloff, C, et al. (författare) Measurement of inclusive jet cross sections in photoproduction at HERA 2003 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 29:4, s. 497-513 Tidskriftsartikel (refereegranskat)abstract Inclusive jet cross sections are measured in photoproduction at HERA using the H1 detector. The data sample of e(+)p --> e(+) + jet + X events in the kinematic range of photon virtualities Q(2) less than or equal to 1GeV(2) and photon-proton centre-of-mass energies 95 less than or equal to W-gammap less than or equal to 285GeV represents an integrated luminosity of 24.1pb(-1). Jets are defined using the inclusive k(perpendicular to) algorithm. Single- and multi-differential cross sections are measured as functions of jet transverse energy E-T(jet) and pseudorapidity eta(jet) in the domain 5 less than or equal to E-T(jet) less than or equal to 75GeV and -1 less than or equal to eta(jet) less than or equal to 2.5. The cross sections are found to be in good agreement with next-to-leading order perturbative QCD calculations corrected for fragmentation and underlying event effects. The cross section differential in E-T(jet), which varies by six orders of magnitude over the measured range, is compared with similar distributions from p (p) over bar colliders at equal and higher energies.
15.	Adloff, C, et al. (författare) Search for excited neutrinos at HERA 2002 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 525:1-2, s. 9-16 Tidskriftsartikel (refereegranskat)abstract We present a search for excited neutrinos using e(-) p data taken by the H1 experiment at HERA at a center-of-mass energy of 318 GeV with an integrated luminosity of 15 pb(-1). No evidence for excited neutrino production is found. Mass dependent exclusion limits are determined for the ratio of the coupling to the compositeness scale, f/Lambda, independently of the relative couplings to the SU(2) and U(1) gauge bosons. These limits extend the excluded region to higher masses than has been possible in previous searches at other colliders.
16.	Adloff, C, et al. (författare) Search for odderon-induced contributions to exclusive pi(0) photoproduction at HERA 2002 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 544:1-2, s. 35-43 Tidskriftsartikel (refereegranskat)abstract A search for contributions to the reaction ep --> epi(0)N* from photon-odderon fusion in the photoproduction regime at HERA is reported, at an average photon-proton centre-of-mass energy = 215 GeV. The measurement proceeds via detection of the pi(0) decay photons, a leading neutron from the N* decay, and the scattered electron. No pi(0) signal is observed and an upper limit on the cross section for the photon-odderon fusion process of sigma(gammap --> pi(0)N*) < 49 nb at the 95% confidence level is derived, integrated over the experimentally accessible range of the squared four-momentum transfer at the nucleon vertex 0.02 < < 0.3 GeV2. This excludes a recent prediction from a calculation based on a non-perturbative QCD model of a photon-odderon fusion cross section above 200 nb. (C) 2002 Elsevier Science B.V. All rights reserved.
17.	Adloff, C, et al. (författare) Search for QCD instanton-induced processes in deep-inelastic scattering at HERA 2002 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 25:4, s. 495-509 Tidskriftsartikel (refereegranskat)abstract Signals of QCD instanton-induced processes are searched for in deep-inelastic scattering (DIS) at the electron-proton collider HERA in a kinematic region defined by the Bjorken-scaling variables x > 10(-3), 0.1 < y < 0.6 and photon virtualities 10 less than or similar to Q(2) < 100 GeV2. Several observables characterising hadronic final state properties of QCD instanton-induced events are exploited to identify a potentially instanton-enriched domain. While an excess of events with instanton-like topology is observed it cannot be claimed significant given the uncertainty of the standard DIS background simulation. Upper limits on the cross-section for instanton-induced processes of between 60 pb and 1000 pb are set dependent on the kinematic domain considered. The data do not exclude the cross-section predicted by instanton perturbation theory for small instanton sizes. At large instanton sizes a naive extrapolation of instanton perturbation theory yields a cross-section in the range of sensitivity of this study. Such a cross-section is not observed, in agreement with non-perturbative lattice simulations of the QCD vacuum.
18.	Aktas, A, et al. (författare) Diffractive photoproduction of J/psi mesons with large momentum transfer at HERA 2003 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 568:3-4, s. 205-218 Tidskriftsartikel (refereegranskat)abstract The diffractive photoproduction of J/psi mesons is measured with the HI detector at the ep collider HERA using an integrated luminosity of 78 pb(-1). The differential cross section dsigma(gammap --> J/psiY)/dt is studied in the range 2 < < 30 GeV2, where t is the square of the four-momentum transferred at the proton vertex. The cross section is also presented as a function of the photon-proton centre-of-mass energy W-gammap in three t intervals, spanning the range 50 < W-gammap < 200 GeV. A fast rise of the cross section with W-gammap is observed for each t range and the slope for the effective linear Pomeron trajectory is measured to be alpha' = -0.0135 +/- 0.0074(stat.) +/- 0.0051(syst.) GeV-2. The measurements are compared with perturbative QCD models based on BFKL and DGLAP evolution. The data are found to be compatible with s-channel helicity conservation. (C) 200 Published by Elsevier B.V.
19.	Aktas, A, et al. (författare) Inclusive dijet production at low Bjorken-x in deep inelastic scattering 2004 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 33:4, s. 477-493 Tidskriftsartikel (refereegranskat)abstract Dijet production in deep inelastic ep scattering is investigated in the region of low values of the Bjorken-variable x (10(-4) < x < 10(-2)) and low photon virtualities Q(2) (5 < Q(2) < 100 GeV2). The measured dijet cross sections are compared with perturbative QCD calculations in next-to-leading order. For most dijet variables studied, these calculations can provide a reasonable description of the data over the full phase space region covered, including the region of very low x. However, large discrepancies at low x and low Q(2) are observed for events with small separation in azimuth between the two highest transverse momentum jets. This region of phase space is described better by predictions based on the CCFM evolution equation, which incorporates k(t) factorized unintegrated parton distributions. A reasonable description can be also obtained using the Color Dipole Model or models incorporating virtual photon structure.
20.	Aktas, A, et al. (författare) Multi-electron production at high transverse momenta in ep collisions at HERA 2003 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 31:1, s. 17-29 Tidskriftsartikel (refereegranskat)abstract Multi-electron production is studied at high electron transverse momentum in positron- and electron-proton collisions using the H1 detector at HERA. The data correspond to an integrated luminosity of 115 pb(-1). Di-electron and tri-electron event yields are measured. Cross sections are derived in a restricted phase space region dominated by photon-photon collisions. In general good agreement is found with the Standard Model predictions. However, for electron pair invariant masses above 100 GeV, three di-electron events and three tri-electron events are observed, compared to Standard Model expectations of 0.30 +/- 0.04 and 0.23 +/- 0.04, respectively.
21.	Aktas, A, et al. (författare) Search for single top quark production in ep collisions at HERA 2004 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 33:1, s. 9-22 Tidskriftsartikel (refereegranskat)abstract A search for single top quark production is performed in e(+/-) pcollisions at HERA. The search exploits data corresponding to an integrated luminosity of 118.3 pb(-1). A model for the anomalous production of top quarks in a flavour changing neutral current process involving a tugamma coupling is investigated. Decays of top quarks into a b quark and a W boson are considered in the leptonic and the hadronic decay channels of the W. Both a cut-based analysis and a multivariate likelihood analysis are performed to discriminate anomalous top quark production from Standard Model background processes. In the leptonic channel, 5 events are found while 1.31 +/- 0.22 events are expected from the Standard Model background. In the hadronic channel, no excess above the expectation for Standard Model processes is found. These observations lead to a cross section (ep --> e t X) = 0.29(-0.14)(+0.15) pb at roots = 319 GeV. Alternatively, assuming that the observed events are due to a statistical fluctuation, upper limits of 0.55 pb on the anomalous top production cross section and of 0.27 on the tugamma coupling k(tugamma) are established at the 95% confidence level.
22.	Aktas, A, et al. (författare) Search for squark production in R-parity violating supersymmetry at HERA 2004 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 36:4, s. 425-440 Tidskriftsartikel (refereegranskat)abstract A search for squarks in R-parity violating supersymmetry is performed in e(+/-)p collisions at HERA using the H1 detector. The data were taken at a centre-of-mass energy of 319 GeV and correspond to an integrated luminosity of 64.3 pb(-1) for e (+) p collisions and 13.5 pb(-1) for e(-)p collisions. The resonant production of squarks via a Yukawa coupling lambda' is considered, taking into account direct and indirect R-parity violating decay modes. No evidence for squark production is found in the multi-lepton and multi-jet final state topologies investigated. Mass dependent limits on lambda' are obtained in the framework of the Minimal Supersymmetric Standard Model. In addition, the results are interpreted in terms of constraints on the parameters of the minimal Supergravity model. At the 95% confidence level squarks of all flavours with masses up to 275 GeV are excluded in a large part of the parameter space for a Yukawa coupling of electromagnetic strength. For a coupling strength 100 times smaller, masses up to 220 GeV can be ruled out.
23.	Adloff, C, et al. (författare) Diffractive photoproduction of psi(2S) mesons at HERA 2002 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 541:3-4, s. 251-264 Tidskriftsartikel (refereegranskat)abstract Results on diffractive photoproduction of psi(2S) mesons are presented using data collected between 1996 and 2000 with the H1 detector at the HERA ep collider. The data correspond to an integrated luminosity of 77 pb(-1). The energy dependence of the diffractive psi(2S) cross section is found to be similar to or possibly somewhat steeper than that for J/psi mesons. The dependences of the elastic and proton dissociative psi(2S) photoproduction cross sections on the squared momentum transfer t at the proton vertex are measured. The t-dependence of the elastic channel, parametrised as e(bt), yields b(el)(psi(2S)) = (4.31 +/- 0.57 +/- 0.46) GeV-2, compatible with that of the J/psi. For the proton dissociative channel the result b(pd)(psi(2S)) = (0.59 +/- 0.13 +/- 0.12) GeV-2 is 2.3 standard deviations smaller than that measured for the J/psi. With proper account of the individual wavefunctions theoretical predictions based on perturbative QCD are found to describe the measurements well. (C) 2002 Elsevier Science B.V. All rights reserved.
24.	Adloff, C, et al. (författare) Inelastic photoproduction of J/psi mesons at HERA 2002 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 25:1, s. 25-39 Tidskriftsartikel (refereegranskat)abstract An analysis of inelastic photoproduction of J/psi mesons is presented using data collected at the ep collider HERA corresponding to an integrated luminosity of above 80 pb(-1), Differential and double I < P-t/psi(2) < differential cross sections are measured in a wide kinematic region: 60 < W-gammap < 260 GeV, 1 p(t,psi)(2) < 60 GeV2 and 0.05 < z < 0.9. where z is the fraction of the energy of the exchanged photon transferred to the J/psi meson in the rest frame of the target proton. Cross sections at z less than or similar to 0.3 are presented for the first time. Theoretical calculations within the Colour Singlet Model at NLO for direct photon processes are shown to give a good description of the data in the medium z region (0.3 < z < 0.9) up to the highest p(t,psi)(2) values. A calculation using a k(t) factorisation approach in LO in the Colour Singlet Model is also able to describe these data. The data in the full z range are also compared to LO calculations within a non-relativistic QCD framework including colour octet and colour singlet contributions for direct and resolved photons. It seems possible to reconcile data and theory with modest contributions from colour octet processes. The polarisation of the J/psi meson is measured as a function of z and p(t,psi) and is reasonably described by the theoretical predictions.
25.	Adloff, C, et al. (författare) Measurement and QCD analysis of neutral and charged current cross sections at HERA 2003 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 30:1, s. 1-32 Tidskriftsartikel (refereegranskat)abstract The inclusive e(+)p single and double differential cross sections for neutral and charged current processes axe measured with the H1 detector at HERA. The data were taken in 1999 and 2000 at a centre-of-mass energy of roots = 319 GeV and correspond to an integrated luminosity of 65.2 pb(-1). The cross sections are measured in the range of four-momentum transfer squared Q(2) between 100 and 30 000 GeV2 and Bjorken x between 0.0013 and 0.65. The neutral current analysis for the new e(+)p data and the earlier e-p data taken in 1998 and 1999 is extended to small energies of the scattered electron and therefore to higher values of inelasticity y, allowing a determination of the longitudinal structure function F-L at high Q(2) (110 - 700 GeV2). A new measurement of the structure function x (F) over tilde (3) is obtained using the new e(+)p and previously published e p neutral current cross section data at high Q(2). These data together with H1 low Q(2) precision data are further used to perform new next-to-leading order QCD analyses in the framework of the Standard Model to extract flavour separated parton distributions in the proton.
26.	Adloff, C, et al. (författare) Measurement of inclusive jet cross-sections in deep-inelastic ep scattering at HERA 2002 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 542:3-4, s. 193-206 Tidskriftsartikel (refereegranskat)abstract A measurement of inclusive jet cross-sections in deep-inelastic ep scattering at HERA is presented based on data with an integrated luminosity of 21.1 pb(-1). The measurement is performed for photon virtualities Q(2) between 5 and 100 GeV2, differentially in Q(2), in the jet transverse energy E-T, in E-T(2)/Q(2) and in the pseudorapidity eta(lab). With the renormalization scale mu(R) = E-T, perturbative QCD calculations in next-to-leading order (NLO) give a good description of the data in most of the phase space. Significant discrepancies are observed only for jets in the proton beam direction with ET below 20 GeV and Q2 below 20 GeV2. This corresponds to the region in which NLO corrections are largest and further improvement of the calculations is thus of particular interest.
27.	Adloff, C, et al. (författare) Search for excited electrons at HERA 2002 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 548:1-2, s. 35-44 Tidskriftsartikel (refereegranskat)abstract A search for excited electron (e) production is described in which the electroweak decays e --> egamma, e* --> eZ and e* ---> nuW are considered. The data used correspond to an integrated luminosity of 120 pb(-1) taken in e(+/-)p collisions from 1994 to 2000 with the H1 detector at HERA at centre-of-mass energies of 300 and 318 GeV. No evidence for a signal is found. Mass dependent exclusion limits are derived for the ratio of the couplings to the compositeness scale, f/A. These limits extend the excluded region to higher masses than has been possible in previous direct searches for excited electrons. (C) 2002 Published by Elsevier Science B.V.
28.	Adloff, C, et al. (författare) Search for new physics in e +/- q contact interactions at HERA 2003 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 568:1-2, s. 35-47 Tidskriftsartikel (refereegranskat)abstract Deep-inelastic e(+/-) p scattering at high squared momentum transfer Q(2) up to 30 000 GeV2 is used to search for eq contact interactions associated to scales far beyond the HERA centre of mass energy. The neutral current cross section measurements dsigma / dQ(2), corresponding to integrated luminosities of 16.4 pb(-1) of e(-) p data and 100.8 pb(-1) of e(+) p data, are well described by the Standard Model and are analysed to set constraints on new phenomena. For conventional contact interactions lower limits are set on compositeness scales A ranging between 1.6-5.5 TeV. Couplings and masses of leptoquarks and squarks in R-parity violating supersymmetry are constrained to M / lambda > 0.3-1.4 TeV. A search for low scale quantum gravity effects in models with large extra dimensions provides limits on the effective Planck scale of MS > 0.8 TeV. A form factor analysis yields a bound on the radius of light quarks of R-q < 1.0 10(-18) m. (C) 2003 Published by Elsevier B.V.
29.	Andreev, V, et al. (författare) Isolated electrons and muons in events with missing transverse momentum at HERA 2003 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 561:3-4, s. 241-257 Tidskriftsartikel (refereegranskat)abstract A search for events with a high-energy isolated electron or muon and missing transverse momentum has been performed at the electron-proton collider HERA using an integrated luminosity of 13.6 pb(-1) in e(-) p scattering and 104.7 pb(-1) in e(+) p scattering. Within the Standard Model such events are expected to be mainly due to W boson production with subsequent leptonic decay. In e(-) p interactions one event is observed in the electron channel and none in the muon channel, consistent with the expectation of the Standard Model. In the e(+) p data a total of 18 events are seen in the electron and muon channels compared to an expectation of 12.4 +/- 1.7 dominated by W production (9.4 +/- 1.6). Whilst the overall observed number of events is broadly in agreement with the number predicted by the Standard Model, there is-an excess of events with transverse momentum of the hadronic system greater than 25 GeV with 10 events found compared to 2.9 +/- 0.5 expected. The results are used to determine the cross-section for events with an isolated electron or muon and missing transverse momentum. (C) 2003 Published by Elsevier Science B.V.
30.	Aspholm-Hurtig, Marina, et al. (författare) Functional adaptation of BabA, the H. pylori ABO blood group antigen binding adhesin. 2004 Ingår i: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 305:5683, s. 519-22 Tidskriftsartikel (refereegranskat)abstract Adherence by Helicobacter pylori increases the risk of gastric disease. Here, we report that more than 95% of strains that bind fucosylated blood group antigen bind A, B, and O antigens (generalists), whereas 60% of adherent South American Amerindian strains bind blood group O antigens best (specialists). This specialization coincides with the unique predominance of blood group O in these Amerindians. Strains differed about 1500-fold in binding affinities, and diversifying selection was evident in babA sequences. We propose that cycles of selection for increased and decreased bacterial adherence contribute to babA diversity and that these cycles have led to gradual replacement of generalist binding by specialist binding in blood group O-dominant human populations.
31.	Castro-Tirado, A. J., et al. (författare) GRB 030227 : The first multiwavelength afterglow of an INTEGRAL GRB 2003 Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 411:1, s. 315-319 Tidskriftsartikel (refereegranskat)abstract We present multiwavelength observations of a gamma-ray burst detected byINTEGRAL (GRB 030227) between 5.3 hours and ~ 1.7days after the event. Here we report the discovery of a dim opticalafterglow (OA) that would not have been detected by many previoussearches due to its faintess (R ~ 23). This OA was seen to declinefollowing a power law decay with index alpha R = -0.95 +/-0.16. The spectral index beta_ opt/NIR yielded -1.25 +/- 0.14. Thesevalues may be explained by a relativistic expansion of a fireball (withp = 2.0) in the cooling regime. We also find evidence for inverseCompton scattering in X-rays.Based on observations with INTEGRAL, an ESA project with instruments andscience data centre funded by ESA member states (especially the PIcountries: Denmark, France, Germany, Italy, Switzerland, Spain), CzechRepublic and Poland, and with the participation of Russia and the USA.Also partially based on observations collected by the Gamma-Ray BurstCollaboration at ESO (GRACE) at the European Southern Observatory, Chile(ESO Large Programme 165.H-0464).
32.	Andrés, E., et al. (författare) Observation of high-energy neutrinos using Čerenkov detectors embedded deep in Antarctic ice 2001 Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 410:6827, s. 441-443 Tidskriftsartikel (refereegranskat)abstract Neutrinos are elementary particles that carry no electric charge and have little mass. As they interact only weakly with other particles, they can penetrate enormous amounts of matter, and therefore have the potential to directly convey astrophysical information from the edge of the Universe and from deep inside the most cataclysmic high-energy regions. The neutrino's great penetrating power, however, also makes this particle difficult to detect. Underground detectors have observed low-energy neutrinos from the Sun and a nearby supernova2, as well as neutrinos generated in the Earth's atmosphere. But the very low fluxes of high-energy neutrinos from cosmic sources can be observed only by much larger, expandable detectors in, for example, deep water3,4 or ice5. Here we report the detection of upwardly propagating atmospheric neutrinos by the ice-based Antarctic muon and neutrino detector array (AMANDA). These results establish a technology with which to build a kilometre-scale neutrino observatory necessary for astrophysical observations1.
33.	Andrés, E., et al. (författare) Recent results from AMANDA 2001 Ingår i: International Journal of Modern Physics A. - 0217-751X .- 1793-656X. ; 16:1C, s. 1013-1015 Tidskriftsartikel (refereegranskat)abstract We present results based on data taken in 1997 with the 302-PMT Antarctic Muon and Neutrino Detector Array-B10 ("AMANDA-B10") array. Atmospheric neutrinos created in the northern hemisphere are observed indirectly through their charged current interactions which produce relativistic, Cherenkov-light-emitting upgoing muons in the South Pole ice cap. The reconstructed angular distribution of these events is in good agreement with expectation and demonstrates the viability of this ice-based device as a neutrino telescope.
34.	Karle, A., et al. (författare) Observation of high energy atmospheric neutrinos with AMANDA 2000 Ingår i: AIP Conference Proceedings. - : American Institute of Physics (AIP). ; , s. 823-827 Konferensbidrag (refereegranskat)abstract In 1997 the Antarctic Muon and Neutrino Detector Array (AMANDA) started operating with 10 strings. In an analysis of data taken during the first year of operation 188 atmospheric neutrino candidates were found. Their zenith angle distribution agrees with expectations based on Monte Carlo simulations. A preliminary upper limit is given on a diffuse flux of high energy neutrinos of astrophysical origin.
35.	Perez-Gomez, B, et al. (författare) Cutaneous melanoma: hints from occupational risks by anatomic site in Swedish men 2004 Ingår i: Occupational and environmental medicine. - : BMJ. - 1470-7926 .- 1351-0711. ; 61:2, s. 117-126 Tidskriftsartikel (refereegranskat)
36.	Aebi, C, et al. (författare) Combination antiretroviral therapy and duration of pregnancy 2000 Ingår i: AIDS (London, England). - : Ovid Technologies (Wolters Kluwer Health). - 0269-9370. ; 14:18, s. 2913-2920 Tidskriftsartikel (refereegranskat)
37.	Aguillon, JC, et al. (författare) Tc45, a dimorphic Trypanosoma cruzi immunogen with variable chromosomal localization, is calreticulin 2000 Ingår i: The American journal of tropical medicine and hygiene. - 0002-9637. ; 63:5-6, s. 306-312 Tidskriftsartikel (refereegranskat)
38.	Ahrens, J., et al. (författare) Initial results from AMANDA 2001 Ingår i: 21st Rencontres de Moriond Workshop on Very High-Energy Phenomena in the Universe. Konferensbidrag (refereegranskat)
39.	Ahrens, J., et al. (författare) Observation of high energy atmospheric neutrinos with the Antarctic muon and neutrino detector array 2002 Ingår i: Physical Review D. - : American Physical Society. - 1550-7998 .- 1550-2368. ; 66:1, s. 120051-1200520 Tidskriftsartikel (refereegranskat)abstract The Antarctic muon and neutrino detector array (AMANDA) began collecting data with ten strings in 1997. Results from the first year of operation are presented. Neutrinos coming through the Earth from the Northern Hemisphere are identified by secondary muons moving upward through the array. Cosmic rays in the atmosphere generate a background of downward moving muons, which are about 106 times more abundant than the upward moving muons. Over 130 days of exposure, we observed a total of about 300 neutrino events. In the same period, a background of 1.05 × 109 cosmic ray muon events was recorded. The observed neutrino flux is consistent with atmospheric neutrino predictions. Monte Carlo simulations indicate that 90% of these events lie in the energy range 66 GeV to 3.4 TeV. The observation of atmospheric neutrinos consistent with expectations establishes AMANDA-B10 as a working neutrino telescope.
40.	Ahrens, J., et al. (författare) Results from AMANDA 2001 Ingår i: Proceedings, 9th International Workshop, Venice, Italy, March 6-9, 2001. Vol. 1, 2. ; , s. 569-580 Konferensbidrag (refereegranskat)
41.	Ahrens, J., et al. (författare) Search for supernova neutrino bursts with the AMANDA detector 2001 Ingår i: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 16:4, s. 345-359 Tidskriftsartikel (refereegranskat)abstract The core collapse of a massive star in the Milky Way will produce a neutrino burst, intense enough to be detected by existing underground detectors. The AMANDA neutrino telescope located deep in the South Pole ice can detect MeV neutrinos by a collective rate increase in all photo-multipliers on top of dark noise. The main source of light comes from positrons produced in the CC reaction of anti-electron neutrinos on free protons ve + p → e+ + n. This paper describes the first supernova search performed on the full sets of data taken during 1997 and 1998 (215 days of live time) with 302 of the detector's optical modules. No candidate events resulted from this search. The performance of the detector is calculated, yielding a 70% coverage of the galaxy with one background fake per year with 90% efficiency for the detector configuration under study. An upper limit at the 90% c.l. on the rate of stellar collapses in the Milky Way is derived, yielding 4.3 events per year. A trigger algorithm is presented and its performance estimated. Possible improvements of the detector hardware are reviewed.
42.	Andres, E., et al. (författare) Observation of atmospheric neutrino events with the AMANDA experiment 2000 Ingår i: Proceedings of the 17th International Workshop on Weak Interactions and Neutrinos. - : World Scientific. - 9810240821 ; , s. 258-262 Konferensbidrag (refereegranskat)
43.	Andres, E., et al. (författare) Results from the AMANDA high energy neutrino detector 2000 Ingår i: Nuclear physics B, Proceedings supplements. - : Elsevier. - 0920-5632 .- 1873-3832. ; 91:1-3, s. 423-430 Tidskriftsartikel (refereegranskat)abstract This paper briefly summarizes the search for astronomical sources of high-energy neutrinos using the AMANDA-B10 detector. The complete data set from 1997 was analyzed. For Eμ > 10 TeV, the detector exceeds 10,000 m2 in effective area between declinations of 25 and 90 degrees. Neutrinos generated in the atmosphere by cosmic ray interactions were used to verify the overall sensitivity of the detector. The absolute pointing accuracy and angular resolution has been confirmed by the analysis of coincident events between the SPASE air shower array and the AMANDA detector. Preliminary flux limits from point source candidates are presented. For declinations larger than +45 degrees, our results compare favorably to existing limits for sources in the Southern sky. We also present the current status of the searches for high energy neutrino emission from diffusely distributed sources, GRBs, and WIMPs from the center of the earth.
44.	Bai, X., et al. (författare) Status of the Neutrino Telescope AMANDA : Monopoles and WIMPS 2001 Ingår i: Dark Matter in Astro- and Particle Physics. - Berlin, Heidelberg : Springer. - 9783642626081 ; , s. 699-706 Konferensbidrag (refereegranskat)abstract The neutrino telescope AMANDA has been set up at the geographical South Pole as first step to a neutrino telescope of the scale of one cubic kilometer, which is the canonical size for a detector sensitive to neutrinos from Active Galactic Nuclei (AGN), Gamma Ray Bursts (GRB) and Topological Defects (TD). The location and depth in which the detector is installed is given by the requirement to detect neutrinos by the Cherenkov light produced by their reaction products and to keep the background due to atmospheric muons as small as possible. However, a detector optimized for this purpose is also capable to detect the bright Cherenkov light from relativistic Monopoles and neutrino signals from regions with high gravitational potential, where WIMPS are accumulated and possibly annihilate. Both hypothetical particles might contribute to the amount of dark matter. Therefore here a report about the status of the experiment (autumn 2000) and about the status of the search for these particles with the AMANDA B10 sub-detector is given.
45.	Batista, N, et al. (författare) Phase II study of capecitabine in combination with paclitaxel in patients with anthracycline-pretreated advanced/metastatic breast cancer. 2004 Ingår i: Br J Cancer. - 0007-0920. ; 90:9, s. 1740-6 Tidskriftsartikel (refereegranskat)abstract The addition of oral capecitabine to docetaxel improves response rate, time to progression (TTP) and overall survival in anthracycline-pretreated metastatic breast cancer (MBC). This phase II study evaluates the efficacy and safety of a 21-day cycle of oral capecitabine (1000 mg m(-2) twice daily, days 1-14) plus i.v. paclitaxel (175 mg m(-2), day 1) in anthracycline-pretreated advanced/MBC. In all, 73 patients were enrolled at 13 Swedish and Spanish centres. The objective response rate was 52% (95% confidence interval (CI): 40-63%) in the intent-to-treat population, including complete responses in 11%. Disease was stabilised in a further 29%. The median time to disease progression (TTP) was 8.1 months and the median overall survival was 16.5 months. The combination was generally well tolerated with a predictable safety profile. The most common treatment-related nonhaematological adverse events were hand-foot syndrome (42%), alopecia (30%) and diarrhoea (26%). The only treatment-related Grade 3/4 adverse events occurring in >5% of patients were alopecia (22%) and hand-foot syndrome (11%). Grade 3/4 neutropenia and lymphocytopenia were reported in 12 and 14% of patients, respectively. Capecitabine plus paclitaxel is highly active with a favourable safety profile in anthracycline-pretreated MBC.
46.	Canals, JM, et al. (författare) Expression of brain-derived neurotrophic factor in cortical neurons is regulated by striatal target area 2001 Ingår i: The Journal of neuroscience : the official journal of the Society for Neuroscience. - 1529-2401. ; 21:1, s. 117-124 Tidskriftsartikel (refereegranskat)
47.	Fellini, R., et al. (författare) A sensitivity-based commonality strategy for family products of mild variation, with application to automotive body structures 2004 Ingår i: Structural and multidisciplinary optimization (Print). - : Springer Science and Business Media LLC. - 1615-147X .- 1615-1488. ; 27:1-2, s. 89-96 Tidskriftsartikel (refereegranskat)abstract Identification of the product platform is a key step in designing a family of products. This article presents a methodology for selecting the product platform by using information obtained from the individual optimization of the product variants. Under the assumption that the product variety requires only mild design changes, a performance deviation vector is derived by taking into consideration individual optimal designs and sensitivities of functional requirements. Commonality decisions are based on values of the performance deviation vector, and the product family is designed optimally with respect to the chosen platform. The proposed methodology is applied to the design of a family of automotive body structures. Variants are defined by changing the functional requirements they need to satisfy and/or the geometry of the associated finite element models.
48.	Forsén, E, et al. (författare) Fabrication of cantilever based mass sensors inteagrated with CMOS using direct write laser lithography on resist 2004 Ingår i: Nanotechnol 15, S628-S633 (2004). Konferensbidrag (refereegranskat)
49.	Forsen, E, et al. (författare) Fabrication of cantilever based mass sensors integrated with CMOS using direct write laser lithography on resist 2004 Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 15:10, s. 628-633 Tidskriftsartikel (refereegranskat)abstract A CMOS compatible direct write laser lithography technique has been developed for cantilever fabrication on pre-fabricated standard CMOS. We have developed cantilever based sensors for mass measurements in vacuum and air. The cantilever is actuated into lateral vibration by electrostatic excitation and the resonant frequency is detected by capacitive readout. The device is integrated on standard CMOS circuitry. In the work a new direct write laser lithography (DWL) technique is introduced. This laser lithography technique is based on direct laser writing on substrates coated with a resist bi-layer consisting of poly(methyl methacrylate) (PMMA) on lift-off resist (LOR). Laser writing evaporates the PMMA, exposing the LOR. A resist solvent is used to transfer the pattern down to the substrate. Metal lift-off followed by reactive ion etching is used for patterning the structural poly-Si layer in the CMOS. The developed laser lithography technique is compatible with resist exposure techniques such as electron beam lithography. We demonstrate the fabrication of sub-micrometre wide suspended cantilevers as well as metal lift-off with feature line widths down to approximately 500 nm.
50.	Perez-Torres, M. A., et al. (författare) High-resolution radio imaging of young supernovae 2004 Rapport (övrigt vetenskapligt/konstnärligt)abstract The high resolution obtained through the use of VLBI gives an unique opportunity to directly observe the interaction of an expanding radio supernova with its surrounding medium. We present here results from our VLBI observations of the young supernovae SN 1979C, SN 1986J, and SN 2001gd.

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