4,157 research outputs found

    Study of anomalous top quark FCNC interactions via tWtW-channel of single top

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    The potential of the LHC for investigation of anomalous top quark interactions with gluon (tug,tcgtug,tcg) through the production of tWtW-channel of single top quark is studied. In the Standard Model, the single top quarks in the tWtW-channel mode are charge symmetric meaning that σ(pp→t+W−)=σ(pp→tˉ+W+)\sigma(pp\to t+W^{-}) = \sigma(pp\to \bar{t}+W^{+}). However, the presence of anomalous FCNC couplings leads to charge asymmetry. In this paper a method is proposed in which this charge asymmetry may be used to constrain anomalous FCNC couplings. The strength of resulting constraints is estimated for the LHC for the center of mass energies of 7 and 14 TeV.Comment: 13 pages, 4 figures, new references adde

    Electrooxidation of nitrite ions on gold/polyaniline/carbon paste electrode

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    Nitrite ions can penetrate from fertilizers into underground water and consequently contaminate the water and food sources. A facile two-step electrochemical method was used to fabricate gold/polyaniline/carbon paste electrode (Au/PAni/CPE) for nitrite sensing. The Au/PAni/CPE was visualized and characterized by scanning electron microscopy, energy-dispersed X-ray spectroscopy, X-ray diffraction and electrochemical methods. The electrocatalytic activity of bare CPE, PAni/CPE and Au/PAni/CPE toward the electrooxidation of nitrite was examined and compared via cyclic voltammetry. To obtain the optimal condition for fabrication of the electrode, the number of cycles in cyclic voltammetry for synthesis of polyaniline and the deposition time in potentiostatic deposition of gold were optimized with respect to the electrooxidation of nitrite. In a phosphate buffer solution (PBS, pH 7.0), the peak current was linear to the concentration of nitrite in the range from 3.8×10-5 M to 1.0×10-3 M with a detection limit of 2.5×10-5 M. The interference effect on the nitrite detection was also studied. The proposed method was also employed for the determination of nitrite in rain and lake water samples

    A Qualitative Land Suitability Assessment in Gypsiferous Soils of Kerman Province, Iran 1

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    Abstract: The suitability is the aptitude of a given type of land to support a defined use. The process of land suitability classification is the appraisal and grouping of specific areas of land in terms of their suitability for a defined use.This research was performed to study of properties of gypsiferous soils and land suitability evaluation for agronomic productions in the study area. At first, the land maps were studied, then 35 farmlands were chosen, they had gypsic horizon and were scattered in the total plain. Then one profile in each farm was described and catch the samples from all horizons. The total gypsum characteristics, using agricultural instruments and applying of different inputs were studied. Land characteristics for example: salinity, acidity, Sodium Absorption Ratio (SAR), Cation Exchange Capacity (CEC), gypsum content, calcium carbonate content, texture and climate were used to classification of land suitability and land utilization types such as wheat, barely, alfalfa, maize, sugarbeet and potato were studied. meanwhile, plant and climate tables were gathered by sys and givi. The results show that the maximum and average of soil gypsum was 31% and 12% respectively. it is one of the most limitation for crop production. According to key to soil taxonomy(2006), the gypsic and cambic horizons were classified in aridisols and entisols. Parent materials, climate, microrelief (topography), physiography and pendant shapes effect the gypsum formation in the studied area. Investigation and qualitative reviewing of lands show that land suitability have a range of changes in classes from S2 to S3 for wheat with the limitations of gypsum in soils and texture, from S2 to S3 for barley with the limitations of gypsum in soils and texture, from S2 to N2 and S3 to N2 for potato with the limitations of soil acidity and gypsum, and S2 to N1 with the limitation of soil`s texture for sugarbeet, from S2 to N2 and S3 to N2 for alfalfa with the limitations of soil`s acidity and gypsum and topography and from S2 to N2 for onion with the limitations of soil`s gypsum and acidity, respectively. researches show that the average of yield in different production in gypsic and non-gypsiferous soils are different

    Spinal codes

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    Spinal codes are a new class of rateless codes that enable wireless networks to cope with time-varying channel conditions in a natural way, without requiring any explicit bit rate selection. The key idea in the code is the sequential application of a pseudo-random hash function to the message bits to produce a sequence of coded symbols for transmission. This encoding ensures that two input messages that differ in even one bit lead to very different coded sequences after the point at which they differ, providing good resilience to noise and bit errors. To decode spinal codes, this paper develops an approximate maximum-likelihood decoder, called the bubble decoder, which runs in time polynomial in the message size and achieves the Shannon capacity over both additive white Gaussian noise (AWGN) and binary symmetric channel (BSC) models. Experimental results obtained from a software implementation of a linear-time decoder show that spinal codes achieve higher throughput than fixed-rate LDPC codes, rateless Raptor codes, and the layered rateless coding approach of Strider, across a range of channel conditions and message sizes. An early hardware prototype that can decode at 10 Mbits/s in FPGA demonstrates that spinal codes are a practical construction.Massachusetts Institute of Technology (Irwin and Joan Jacobs Presidential Fellowship)Massachusetts Institute of Technology (Claude E. Shannon Assistantship)Intel Corporation (Intel Fellowship

    Measurements of branching fraction ratios and CP-asymmetries in suppressed B^- -> D(-> K^+ pi^-)K^- and B^- -> D(-> K^+ pi^-)pi^- decays

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    We report the first reconstruction in hadron collisions of the suppressed decays B^- -> D(-> K^+ pi^-)K^- and B^- -> D(-> K^+ pi^-)pi^-, sensitive to the CKM phase gamma, using data from 7 fb^-1 of integrated luminosity collected by the CDF II detector at the Tevatron collider. We reconstruct a signal for the B^- -> D(-> K^+ pi^-)K^- suppressed mode with a significance of 3.2 standard deviations, and measure the ratios of the suppressed to favored branching fractions R(K) = [22.0 \pm 8.6(stat)\pm 2.6(syst)]\times 10^-3, R^+(K) = [42.6\pm 13.7(stat)\pm 2.8(syst)]\times 10^-3, R^-(K)= [3.8\pm 10.3(stat)\pm 2.7(syst]\times 10^-3, as well as the direct CP-violating asymmetry A(K) = -0.82\pm 0.44(stat)\pm 0.09(syst) of this mode. Corresponding quantities for B^- -> D(-> K^+ pi^-)pi^- decay are also reported.Comment: 8 pages, 1 figure, accepted by Phys.Rev.D Rapid Communications for Publicatio

    Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

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    A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

    Search for anomalous t t-bar production in the highly-boosted all-hadronic final state