1,379 research outputs found

    NLO QCD corrections to the production of a weak boson pair associated by a hard jet

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    In this talk we discuss recent progress concerning precise predictions for the LHC. We give a status report of an application of the GOLEM method to deal with multi-leg one-loop amplitudes, namely the next-to-leading order QCD corrections to the process pp to V V + jet, where V is a weak boson W,Z.Comment: Talk at 2008 Rencontres de Moriond, QCD session, La Thuile, March 2007. Four page

    NLO QCD corrections to ZZ+jet production at hadron colliders

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    A fully differential calculation of the next-to-leading order QCD corrections to the production of Z-boson pairs in association with a hard jet at the Tevatron and LHC is presented. This process is an important background for Higgs particle and new physics searches at hadron colliders. We find sizable corrections for cross sections and differential distributions, particularly at the LHC. Residual scale uncertainties are typically at the 10% level and can be further reduced by applying a veto against the emission of a second hard jet. Our results confirm that NLO corrections do not simply rescale LO predictions.Comment: 15 pages, 4 figures, 4 tables; added 1 reference, version to appear in Phys. Lett.

    Next-to-leading order multi-leg processes for the Large Hadron Collider

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    In this talk we discuss recent progress concerning precise predictions for the LHC. We give a status report of three applications of our method to deal with multi-leg one-loop amplitudes: The interference term of Higgs production by gluon- and weak boson fusion to order O(alpha^2 alpha_s^3) and the next-to-leading order corrections to the two processes pp -> ZZ jet and u ubar -> d dbar s sbar. The latter is a subprocess of the four jet cross section at the LHC.Comment: 6 pages, 5 figures. Talk given at the 8th international Symposium on Radiative Corrections (RADCOR), October 1-5 2007, Florence, Ital

    Measurements and Simulation Studies of Piezoceramics for Acoustic Particle Detection

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    Calibration sources are an indispensable tool for all detectors. In acoustic particle detection the goal of a calibration source is to mimic neutrino signatures as expected from hadronic cascades. A simple and promising method for the emulation of neutrino signals are piezo ceramics. We will present results of measruements and simulations on these piezo ceramics.Comment: 5 pages, 5 figure

    Climate change and its effect on agriculture, water resources and human health sectors in Poland

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    Multi-model ensemble climate projections in the ENSEMBLES Project of the EU allowed the authors to quantify selected extreme-weather indices for Poland, of importance to climate impacts on systems and sectors. Among indices were: number of days in a year with high value of the heat index; with high maximum and minimum temperatures; length of vegetation period; and number of consecutive dry days. Agricultural, hydrological, and human health indices were applied to evaluate the changing risk of weather extremes in Poland in three sectors. To achieve this, model-based simulations were compared for two time horizons, a century apart, i.e., 1961–1990 and 2061–2090. Climate changes, and in particular increases in temperature and changes in rainfall, have strong impacts on agriculture via weather extremes – droughts and heat waves. The crop yield depends particularly on water availability in the plant development phase. To estimate the changes in present and future yield of two crops important for Polish agriculture i.e., potatoes and wheat, some simple empirical models were used. For these crops, decrease of yield is projected for most of the country, with national means of yield change being: –2.175 t/ha for potatoes and –0.539 t/ha for wheat. Already now, in most of Poland, evapotranspiration exceeds precipitation during summer, hence the water storage (in surface water bodies, soil and ground) decreases. Summer precipitation deficit is projected to increase considerably in the future. The additional water supplies (above precipitation) needed to use the agro-potential of the environment would increase by half. Analysis of water balance components (now and in the projected future) can corroborate such conclusions. As regards climate and health, a composite index, proposed in this paper, is a product of the number of senior discomfort days and the number of seniors (aged 65+). The value of this index is projected to increase over 8-fold during 100 years. This is an effect of both increase in the number of seniors (over twofold) and the number of senior-discomfort days (nearly fourfold)

    Effect of climate change on sporulation of the teleomorphs of Leptosphaeria species causing stem canker of brassicas

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    Leptosphaeria maculans and L. biglobosa are closely related sibling fungal pathogens that cause phoma leaf spotting, stem canker (blackleg) and stem necrosis of oilseed rape (Brassica napus). The disease is distributed worldwide, and it is one of the main causes of considerable decrease in seed yield and quality. Information about the time of ascospore release at a particular location provides important data for decision making in plant protection, thereby enabling fungicides to be used only when necessary and at optimal times and doses. Although the pathogens have been studied very extensively, the effect of climate change on the frequencies and distributions of their aerially dispersed primary inoculum has not been reported to date. We have collected a large dataset of spore counts from Poznan, located in central-west part of Poland, and studied the relationships between climate and the daily concentrations of airborne propagules over a period of 17 years (1998–2014). The average air temperature and precipitation for the time of development of pseudothecia and ascospore release (July–November), increased during the years under study at the rates of 0.1 °C and 6.3 mm per year. The day of the year (DOY) for the first detection of spores, as well as the date with maximum of spores, shifted from 270 to 248 DOY, and from 315 to 265 DOY, respectively. The acceleration of the former parameter by 22 days and the latter by 50 days has great influence on the severity of stem canker of oilseed rape

    Two-phonon 1- state in 112Sn observed in resonant photon scattering

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    Results of a photon scattering experiment on 112Sn using bremsstrahlung with an endpoint energy of E_0 = 3.8 MeV are reported. A J = 1 state at E_x = 3434(1) keV has been excited. Its decay width into the ground state amounts to Gamma_0 = 151(17) meV, making it a candidate for a [2+ x 3-]1- two-phonon state. The results for 112Sn are compared with quasiparticle-phonon model calculations as well as the systematics of the lowest-lying 1- states established in other even-mass tin isotopes. Contrary to findings in the heavier stable even-mass Sn isotopes, no 2+ states between 2 and 3.5 MeV excitation energy have been detected in the present experiment.Comment: 10 pages, including 2 figures, Phys. Rev. C, in pres

    Viking Age garden plants from southern Scandinavia: diversity, taphonomy and cultural aspects

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    Plant finds recovered from archaeological sites in southern Scandinavia dated to the Viking Age reflect the diversity of useful plants that were cultivated and collected. This review presents the results of 14 investigations of deposits that are dated between AD 775 and 1050. The site types are categorized as agrarian, urban, military and burials. Garden plants are unevenly distributed, as the greatest diversity is recorded in features from urban contexts. We argue that taphonomic processes played an important role in the picture displayed. Archaeobotanical research results from neighbouring regions suggest that Viking Age horticulture has its roots in older traditions, and that the spectrum of garden plants is influenced by central and north-western European horticultural customs, which were to a great extent shaped by Roman occupation

    Integration of Acoustic Detection Equipment into ANTARES

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    The ANTARES group at the University of Erlangen is working towards the integration of a set of acoustic sensors into the ANTARES Neutrino Telescope. With this setup, tests of acoustic particle detection methods and background studies shall be performed. The ANTARES Neutrino Telescope, which is currently being constructed in the Mediterranean Sea, will be equipped with the infrastructure to accommodate a 3-dimensional array of photomultipliers for the detection of Cherenkov light. Within this infrastructure, the required resources for acoustic sensors are available: Bandwidth for the transmission of the acoustic data to the shore, electrical power for the off-shore electronics and physical space to install the acoustic sensors and to route the connecting cables (transmitting signals and power) into the electronics containers. It will be explained how the integration will be performed with minimal modifications of the existing ANTARES design and which setup is foreseen for the acquisition of the acoustic data.Comment: 5 pages, 1 figure, to appear in the proceedings of the 1st International ARENA Workshop, May 17-19th, 2005, DESY Zeuthen (Germany
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