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1.	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.
2.	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.
3.	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.
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 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.
6.	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.
7.	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.
8.	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.
9.	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.
10.	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.
11.	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.
12.	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.
13.	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.
14.	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.
15.	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.
16.	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.
17.	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.
18.	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.
19.	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.
20.	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.
21.	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.
22.	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.
23.	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.
24.	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.
25.	Beral, V, et al. (författare) Alcohol, tobacco and breast cancer - collaborative reanalysis of individual data from 53 epidemiological studies, including 58515 women with breast cancer and 95067 women without the disease 2002 Ingår i: British Journal of Cancer. - : Springer Science and Business Media LLC. - 1532-1827 .- 0007-0920. ; 87, s. 1234-45 Tidskriftsartikel (refereegranskat)abstract Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58515 women with invasive breast cancer and 95067 controls from 53 studies. Relative risks of breast cancer were estimated, after stratifying by study, age, parity and, where appropriate, women's age when their first child was born and consumption of alcohol and tobacco. The average consumption of alcohol reported by controls from developed countries was 6.0 g per day, i.e. about half a unit/drink of alcohol per day, and was greater in ever-smokers than never-smokers, (8.4 g per day and 5.0 g per day, respectively). Compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 (1.19 - 1.45, P < 0.00001) for an intake of 35 - 44 g per day alcohol, and 1.46 (1.33 - 1.61, P < 0.00001) for greater than or equal to 45 g per day alcohol. The relative risk of breast cancer increased by 7.1% (95% CI 5.5-8.7%; P<0.00001) for each additional 10 g per day intake of alcohol, i.e. for each extra unit or drink of alcohol consumed on a daily basis. This increase was the same in ever-smokers and never-smokers (7.1 % per 10 g per day, P < 0.00001, in each group). By contrast, the relationship between smoking and breast cancer was substantially confounded by the effect of alcohol. When analyses were restricted to 22 255 women with breast cancer and 40 832 controls who reported drinking no alcohol, smoking was not associated with breast cancer (compared to never-smokers, relative risk for ever-smokers= 1.03, 95% CI 0.98 - 1.07, and for current smokers=0.99, 0.92 - 1.05). The results for alcohol and for tobacco did not vary substantially across studies, study designs, or according to 15 personal characteristics of the women; nor were the findings materially confounded by any of these factors. If the observed relationship for alcohol is causal, these results suggest that about 4% of the breast cancers in developed countries are attributable to alcohol. In developing countries, where alcohol consumption among controls averaged only 0.4 g per day, alcohol would have a negligible effect on the incidence of breast cancer. In conclusion, smoking has little or no independent effect on the risk of developing breast cancer; the effect of alcohol on breast cancer needs to be interpreted in the context of its beneficial effects, in moderation, on cardiovascular disease and its harmful effects on cirrhosis and cancers of the mouth, larynx, oesophagus and liver. (C) 2002 Cancer Research UK.
26.	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.
27.	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.
28.	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.
29.	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.
30.	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.
31.	Aktas, A, et al. (författare) Forward pi(o) production and associated transverse energy flow in deep-inelastic scattering at HERA 2004 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 36:4, s. 441-452 Tidskriftsartikel (refereegranskat)
32.	Dilts, DA, et al. (författare) Phase I clinical trials of aroA aroD and aroA aroD htrA attenuated S. typhi vaccines; effect of formulation on safety and immunogenicity 2000 Ingår i: Vaccine. - 0264-410X. ; 18:15, s. 1473-1484 Tidskriftsartikel (refereegranskat)
33.	Strauch, S, et al. (författare) Polarization transfer in the He-4((e)over-right-arrow,e '(p)over-right-arrow)H-3 reaction up to Q(2)=2.6 (GeV/c)(2) 2003 Ingår i: Physical Review Letters. - 1079-7114. ; 91:5: 052301 Tidskriftsartikel (refereegranskat)abstract We have measured the proton recoil polarization in the He-4((e) over right arrow ,e(')(p) over right arrow)H-4 reaction at Q(2)=0.5, 1.0, 1.6, and 2.6 (GeV/c)(2). The measured ratio of polarization transfer coefficients differs from a fully relativistic calculation, favoring the inclusion of a medium modification of the proton form factors predicted by a quark-meson coupling model. In addition, the measured induced polarizations agree reasonably well with the fully relativistic calculation indicating that the treatment of final-state interactions is under control.
34.	Fickert, P, et al. (författare) Biliary leakage of fluorescent bile acids in MDR2 knockout mice: Evidence for a critical role of bile duct leakage in the pathogenesis of sclerosing cholangitis 2004 Ingår i: JOURNAL OF HEPATOLOGY. - 0168-8278. ; 40, s. 91-91 Konferensbidrag (övrigt vetenskapligt/konstnärligt)
35.	Fickert, P, et al. (författare) Regurgitation of bile acids from leaky bile ducts causes sclerosing cholangitis in Mdr2 (Abcb4) knockout mice 2004 Ingår i: Gastroenterology. - : Elsevier BV. - 0016-5085. ; 127:1, s. 261-274 Tidskriftsartikel (refereegranskat)
36.	Fickert, P, et al. (författare) Ursodeoxycholic acid aggravates bile infarcts in bile duct-ligated and Mdr2 knockout mice via disruption of cholangioles 2002 Ingår i: Gastroenterology. - : Elsevier BV. - 0016-5085. ; 123:4, s. 1238-1251 Tidskriftsartikel (refereegranskat)
37.	Hu, G, et al. (författare) Joint effects of physical activity, body mass index, waist circumference and waist-to-hip ratio with the risk of cardiovascular disease among middle-aged Finnish men and women 2004 Ingår i: European heart journal. - 0195-668X. ; 25:24, s. 2212-2219 Tidskriftsartikel (refereegranskat)
38.	Hu, G, et al. (författare) Occupational, commuting, and leisure-time physical activity in relation to risk for Type 2 diabetes in middle-aged Finnish men and women 2003 Ingår i: Diabetologia. - 0012-186X. ; 46:3, s. 322-329 Tidskriftsartikel (refereegranskat)
39.	Hu, G, et al. (författare) Occupational, commuting, and leisure time physical activity in relation to risk for Type 2 diabetes in middle-aged Finnish men and women 2002 Ingår i: DIABETOLOGIA. - 0012-186X. ; 45, s. A73-A73 Konferensbidrag (övrigt vetenskapligt/konstnärligt)
40.	Hu, G, et al. (författare) Physical activity, body mass index, and risk of type 2 diabetes in patients with normal or impaired glucose regulation 2004 Ingår i: Archives of internal medicine. - 0003-9926. ; 164:8, s. 892-896 Tidskriftsartikel (refereegranskat)
41.	Hu, G, et al. (författare) Plasma insulin and cardiovascular mortality in non-diabetic European men and women : a meta-analysis of data from eleven prospective studies. 2004 Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 47:7, s. 1245-56 Tidskriftsartikel (refereegranskat)
42.	Hu, H, et al. (författare) Insulin, but not proinsulin C-peptide, enhances platelet fibrinogen binding in vitro in Type 1 diabetes mellitus patients and healthy subjects 2002 Ingår i: Thrombosis research. - : Elsevier BV. - 0049-3848. ; 106:2, s. 91-95 Tidskriftsartikel (refereegranskat)
43.	Hu, W. K., et al. (författare) AB(5)-type hydrogen storage alloys as catalysts in hydrogen-diffusion electrodes for novel H-2/hydride//perovskite/O-2 alkaline fuel cells 2004 Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 108:48, s. 18530-18534 Tidskriftsartikel (refereegranskat)abstract Development of a non-noble-metal catalyst electrode is an important issue in the research and development of fuel cells. The catalytic activity and durability of AB(5)-type hydrogen storage alloys used in hydrogen-diffusion electrodes for alkaline fuel cells are evaluated. The experiments demonstrate that the activity and stability for hydrogen oxidation is greatly improved if the particle size is decreased from 5-30 to 1-10 mum. This also improves the electrode stability. SEM and XRD analyses show that no disintegration of the smaller catalyst particles is observed in long-term tests. A novel H-2/hydride//perovskite/O-2 alkaline fuel cell was constructed as a non-noble-metal fuel cell concept. The results showed that both gas-diffusion electrodes had high catalytic activities and good stability. A maximum power density of 54 mW/cm(2) was achieved at 120 mA/cm(2) when using H-2/O-2 and 49 mW/cm(2) at 100 mA/cm(2) when using H-2/air.
44.	Hu, W. K., et al. (författare) Zr-based AB(2)-type hydrogen storage alloys as dual catalysts of gas-diffusion electrodes in an alkaline fuel cell 2004 Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 108:26, s. 8756-8758 Tidskriftsartikel (refereegranskat)abstract Zr-based AB(2)-type hydrogen storage alloys as dual catalysts for hydrogen adsorption and oxidation reactions in alkaline fuel cells were investigated. A hydrogen-diffusion electrode composed of this hydride alloy was constructed, and its performance in terms of catalytic activities and durability was evaluated. Results demonstrated that the hydrogen-diffusion electrode had not only good activity but also excellent stability at a current density of 40-60 mA/cm(2) after surface treatments using a 1.0 M HF solution. XPS analyses showed that the improvement in catalytic activity is related to the formation of a nickel-rich layer and the removal of other oxides on the catalyst surface. The novel possible application of Zr-based hydride alloys could lead to an attempt to exploit new catalysts to lower material cost for hydrogen fuel cells.
45.	Lind, PA, et al. (författare) Myocardial perfusion changes in patients irradiated for left-sided breast cancer and correlation with coronary artery distribution 2003 Ingår i: International journal of radiation oncology, biology, physics. - 0360-3016. ; 55:4, s. 914-920 Tidskriftsartikel (refereegranskat)
46.	Percec, V., et al. (författare) Self-assembly of amphiphilic dendritic dipeptides into helical pores 2004 Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 430:7001, s. 764-768 Tidskriftsartikel (refereegranskat)abstract Natural pore-forming proteins act as viral helical coats(1) and transmembrane channels(2-4), exhibit antibacterial activity(5) and are used in synthetic systems, such as for reversible encapsulation(6) or stochastic sensing(7). These diverse functions are intimately linked to protein structure(1-4). The close link between protein structure and protein function makes the design of synthetic mimics a formidable challenge, given that structure formation needs to be carefully controlled on all hierarchy levels, in solution and in the bulk. In fact, with few exceptions(8,9), synthetic pore structures capable of assembling into periodically ordered assemblies that are stable in solution and in the solid state(10-13) have not yet been realized. In the case of dendrimers, covalent(14) and non- covalent(15) coating and assembly of a range of different structures(15-17) has only yielded closed columns(18). Here we describe a library of amphiphilic dendritic dipeptides that self-assemble in solution and in bulk through a complex recognition process into helical pores. We find that the molecular recognition and self-assembly process is sufficiently robust to tolerate a range of modifications to the amphiphile structure, while preliminary proton transport measurements establish that the pores are functional. We expect that this class of self-assembling dendrimers will allow the design of a variety of biologically inspired systems with functional properties arising from their porous structure.
47.	Rekhi, S., et al. (författare) Experimental and theoretical investigations on the compressibility of nanocrystalline nickel 2001 Ingår i: Journal of Materials Science. - 0022-2461 .- 1573-4803. ; 36:19, s. 4719-4721 Tidskriftsartikel (refereegranskat)
48.	Sarlio-Lahteenkorva, S, et al. (författare) The association between thinness and socio-economic disadvantage, health indicators, and adverse health behaviour: a study of 28 000 Finnish men and women 2004 Ingår i: International journal of obesity and related metabolic disorders : journal of the International Association for the Study of Obesity. - 0307-0565. ; 28:4, s. 568-573 Tidskriftsartikel (refereegranskat)
49.	Wagner, M, et al. (författare) Adaptive renal ABC transporter expression in common bile duct-ligated mice 2004 Ingår i: JOURNAL OF HEPATOLOGY. - 0168-8278. ; 40, s. 26-26 Konferensbidrag (övrigt vetenskapligt/konstnärligt)
50.	Wagner, M, et al. (författare) Gender and pregnancy affect hepatic and renal ABC transporter expression in mice 2004 Ingår i: JOURNAL OF HEPATOLOGY. - 0168-8278. ; 40, s. 94-94 Konferensbidrag (övrigt vetenskapligt/konstnärligt)

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