69 research outputs found

    Electrically and Magnetically Charged States and Particles in the 2+1-Dimensional Z_N-Higgs Gauge Model

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    Electrically as well as magnetically charged states are constructed in the 2+1-dimensional Euclidean Z_N-Higgs lattice gauge model, the former following ideas of Fredenhagen and Marcu and the latter using duality transformations on the algebra of observables. The existence of electrically and of magnetically charged particles is also established. With this work we prepare the ground for the constructive study of anyonic statistics of multiparticle scattering states of electrically and magnetically charged particles in this model (work in progress).Comment: 57 pages, Sfb 288 Preprint No. 109. To appear in Commun. Math. Phys. About the file: This is a uuencoded, "gzip-ed" postscript file. It is about 300kB large. The original ps file is about 700kB large. All figures are included. The LaTeX sources ou even hard copies can be required to the authors at [email protected] or Freie Universitaet Berlin. Institut fuer Theoretische Physik. Arnimallee 14. Berlin 14195 German

    NLO corrections to differential cross sections for pseudo-scalar Higgs boson production

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    We have computed the full next-to-leading (NLO) QCD corrections to the differential distributions d2σ/(dpT dy)d^2\sigma/(dp_T~dy) for pseudo-scalar Higgs (A) production at large hadron colliders. This calculation has been carried out using the effective Lagrangian approach which is valid as long as the mass of the pseudo-scalar Higgs boson mAm_{\rm A} and its transverse momentum pTp_T do not exceed the top-quark mass mtm_t. The shape of the distributions hardly differ from those obtained for scalar Higgs (H) production because, apart from the overall coupling constant and mass, there are only small differences between the partonic differential distributions for scalar and pseudo-scalar production. Therefore there are only differences in the magnitudes of the hadronic differential distributions which can be mainly attributed to the unknown mixing angle β\beta describing the pseudo-scalar Higgs coupling to the top quarks.Comment: 9 pages, LaTeX, 3 Postscript figures In the previous version we have forgotten to include contributions which arrise from interferences between graphs containing vertices corresponding to the operator O2(x)O_2(x) in Eq. (3) with graphs originating from the operator O1(x)O_1(x). These interferences occur because of the prescription for the Levi-Civita tensor given in our paper. These extra contributions are added to Eqs. (19) and (20). Numerically they are completely negligible so that the figures are not altere

    A systematic study of J/psi suppression in cold nuclear matter

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    Based on a Glauber model, a statistical analysis of all mid-rapidity J/psi hadroproduction and leptoproduction data on nuclear targets is carried out. This allows us to determine the J/psi-nucleon inelastic cross section, whose knowledge is crucial to interpret the J/psi suppression observed in heavy-ion collisions, at SPS and at RHIC. The values of sigma are extracted from each experiment. A clear tension between the different data sets is reported. The global fit of all data gives sigma=3.4+/-0.2 mb, which is significantly smaller than previous estimates. A similar value, sigma=3.5+/-0.2 mb, is obtained when the nDS nuclear parton densities are included in the analysis, although we emphasize that the present uncertainties on gluon (anti)shadowing do not allow for a precise determination of sigma. Finally, no significant energy dependence of the J/psi-N interaction is observed, unless strong nuclear modifications of the parton densities are assumed.Comment: 25 pages, 5 figure

    The role of nutraceuticals and phytotherapy in the management of urinary tract infections: What we need to know?

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    Urinary Tract Infections (UTIs) are amongst the most common infectious diseases and carry a significant impact on patient quality of life and health care costs. Despite that, there is no well-established recommendation for a "standard" prophylactic antibiotic management to prevent UTI recurrences. The majority of patients undergoes long-term antibiotic treatment that severely impairs the normal microbiota and increases the risk of development of multidrugresistant microorganisms. In this scenario, the use of phytotherapy to both alleviate symptoms related to UTI and decrease the rate of symptomatic recurrences is an attractive alternative. Several recently published papers report conflicting findings and cannot give confident recommendations for the everyday clinical practice. A new approach to the management of patients with recurrent UTI might be to use nutraceuticals or phytotherapy after an accurate assessment of the patient`s risk factors. No single compound or mixture has been identified so far as the best preventive approach in patients with recurrent UTI. We reviewed our non-antibiotic approach to the management of recurrent UTI patients in order to clarify the evidence-base for the commonly used substances, understand their pharmacokinetics and pharmacodynamics in order to tailor the best way to improve patient's quality of life and reduce the rate of antibiotic resistance. Lack of a gold-standard recommendation and the risk of increasing antibiotic resistance is the reason why we need alternatives to antibiotics in the management of urinary tract infections (UTIs). A tailored approach according to bacterial characteristics and the patient risk factors profile is a promising option

    Higgs Boson Decay into Hadronic Jets

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    The remarkable agreement of electroweak data with standard model (SM) predictions motivates the study of extensions of the SM in which the Higgs boson is light and couples in a standard way to the weak gauge bosons. Postulated new light particles should have small couplings to the gauge bosons. Within this context it is natural to assume that the branching fractions of the light SM-like Higgs boson mimic those in the standard model. This assumption may be unwarranted, however, if there are non-standard light particles coupled weakly to the gauge bosons but strongly to the Higgs field. In particular, the Higgs boson may effectively decay into hadronic jets, possibly without important bottom or charm flavor content. As an example, we present a simple extension of the SM, in which the predominant decay of the Higgs boson occurs into a pair of light bottom squarks that, in turn, manifest themselves as hadronic jets. Discovery of the Higgs boson remains possible at an electron-positron linear collider, but prospects at hadron colliders are diminished substantially.Comment: 30 pages, 7 figure

    Direct 17O Isotopic Labeling of Oxides Using Mechanochemistry

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    While 17O NMR is increasingly being used for elucidating the structure and reactivity of complex molecular and materials systems, much effort is still required for it to become a routine analytical technique. One of the main difficulties for its development comes from the very low natural abundance of 17O (0.04%), which implies that isotopic labeling is generally needed prior to NMR analyses. However, 17O-enrichment protocols are often unattractive in terms of cost, safety, and/or practicality, even for compounds as simple as metal oxides. Here, we demonstrate how mechanochemistry can be used in a highly efficient way for the direct 17O isotopic labeling of a variety of s-, p-, and d-block oxides, which are of major interest for the preparation of functional ceramics and glasses: Li2O, CaO, Al2O3, SiO2, TiO2, and ZrO2. For each oxide, the enrichment step was performed under ambient conditions in less than 1 h and at low cost, which makes these synthetic approaches highly appealing in comparison to the existing literature. Using high-resolution solid-state 17O NMR and dynamic nuclear polarization, atomic-level insight into the enrichment process is achieved, especially for titania and alumina. Indeed, it was possible to demonstrate that enriched oxygen sites are present not only at the surface but also within the oxide particles. Moreover, information on the actual reactions occurring during the milling step could be obtained by 17O NMR, in terms of both their kinetics and the nature of the reactive species. Finally, it was demonstrated how high-resolution 17O NMR can be used for studying the reactivity at the interfaces between different oxide particles during ball-milling, especially in cases when X-ray diffraction techniques are uninformative. More generally, such investigations will be useful not only for producing 17O-enriched precursors efficiently but also for understanding better mechanisms of mechanochemical processes themselves

    Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV

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    A search for a Higgs boson decaying into two photons is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross section of the standard model Higgs boson decaying to two photons. The expected exclusion limit at 95% confidence level is between 1.4 and 2.4 times the standard model cross section in the mass range between 110 and 150 GeV. The analysis of the data excludes, at 95% confidence level, the standard model Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The largest excess of events above the expected standard model background is observed for a Higgs boson mass hypothesis of 124 GeV with a local significance of 3.1 sigma. The global significance of observing an excess with a local significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is estimated to be 1.8 sigma. More data are required to ascertain the origin of this excess.Comment: Submitted to Physics Letters

    Measurement of isolated photon production in pp and PbPb collisions at sqrt(sNN) = 2.76 TeV

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    Isolated photon production is measured in proton-proton and lead-lead collisions at nucleon-nucleon centre-of-mass energies of 2.76 TeV in the pseudorapidity range |eta|<1.44 and transverse energies ET between 20 and 80 GeV with the CMS detector at the LHC. The measured ET spectra are found to be in good agreement with next-to-leading-order perturbative QCD predictions. The ratio of PbPb to pp isolated photon ET-differential yields, scaled by the number of incoherent nucleon-nucleon collisions, is consistent with unity for all PbPb reaction centralities.Comment: Submitted to Physics Letters
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