2,433 research outputs found

    Single Top production at CMS

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    A first measurement of the cross section of single top quark production in the t channel in pp collision at sqrt(s)=7 TeV is presented. The measurement is performed on a data sample corresponding to an integrated luminosity of 35.9 pb^-1 recorded at the LHC with the CMS detector. Leptonic decay channels with an electron or a muon in the final state are considered. After a selection optimized for the t-channel mode, two different and complementary analyses have been performed. Both analyses confirm the Tevatron's observation of single top, and their combination measures a cross section of sigma = 83.6 +/- 29.8(stat.+syst.) +/- 3.3 (lumi.) pb, which is consistent with the Standard Model prediction.Comment: 7 pages, 3 figures, Proceedings of the DPF-2011 Conference, Providence, RI, August 8-13, 201

    The ATLAS and CMS Detectors and Triggers for B physics

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    The ATLAS and CMS detectors are the two general purpose experiments which will be operated at the LHC, and these have been designed to explore the full range of physics that can be accessed at LHC energies. With the large b production cross section and high luminosity foreseen a substantial number of b-flavoured hadrons can be expected to be recorded. For both experiments, a brief description of the most relevant detectors, the trigger systems and the trigger strategy envisaged for B physics is presented

    B physics at CMS

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    The Compact Muon Solenoid (CMS) is a multi-purpose detector which will be operated at the Large Hadron Collider (LHC) at CERN. The capabilities of the CMS experiment in the field of BB physics has been studied in several benchmark processes which are representative of exclusive BB physics analysis. They allow to study the capability of CMS to identify, select and reconstruct the decay of the bb-flavoured hadrons, which presents a significant challenge due to their relatively low momentum and high background

    Strategies for btagging calibration using collider data at CMS

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    The CMS Collaboration is studying several algorithms to identify jets coming from the hadronization of bottom quarks (b-jets) which are present in a wide range of physics processes of interests such as in the decay of top quarks, Higgs bosons and several non-Standard Model particles. All of these b-tagging algorithms rely upon the reconstruction of lower level objects like tracks, vertices, and jets, which might make it difficult for the Monte Carlo simulation to exactly reproduce the performance observed in data. Reliable methods to measure performance of these algorithms directly from collider data have been developed. The CMS b-tagging group is working on several strategies which should yield reliable results already with 10‚ÄÖ‚Ääpb‚ąí110\;\rm{pb}^{-1} of integrated luminosity

    Lorentz angle calibration for the barrel pixel detector

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    A method to measure the Lorentz angle in the barrel pixel detector of CMS is presented. This measurement from CMS data will be necessary during operation since the electric field in the sensors will change with increasing irradiation. The approach described in this note uses well measured muon tracks to determine the drift of the electrons in the pixel sensors. From an analysis of simulated data an accuracy of 2% on tau_L can be achieved from just 1000 muon tracks. This corresponds to a systematic shift in the hit reconstruction of less than 1.5 \mu m which will decrease with increasing integrated luminosity

    Proteção de camundongos atímicos BALB/c (Nu/Nu) contra Plasmodium berghei por esplenócitos oriundos de camundongos normais BALB/c (Nu/+)

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    Camundongos at√≠micos BALB/c (Nu/Nu) sucumbem entre 7-13 dias ap√≥s a inocula√ß√£o (DAI) da cepa NK65 de Plasmodium berghei. Todavia, seus singen√™icos heterozigotos (Nu/+) morrem em 7-8 DAI. Camundongos nude (Nu/Nu) reconstitu√≠dos com 2xl0(7) esplen√≥citos de camundongos heterozigotos singen√™icos normais n√£o infectados (Nu/+) 20 dias antes da inocula√ß√£o a (DBI) do parasita, sucumbem 2 dias antes que os animais controles. Camundongos nude reconstitu√≠dos 10 ou 2 DBI, vivem 2-4 dias a mais que os animais controles e alguns deles sobrevivem. Esses achados indicam que a cepa NK65 de P. berghei induz, no m√≠nimo, dois imunofen√īmenos dependentes de linf√≥citos T; um supressivo e outro estimulat√≥rio. A reconstitui√ß√£o de camundongos nude com c√©lulas T de camundongos BALB/c (Nu/+) parece reduzir ou "By-pass" a atividade supressora das c√©lulas T, o qual leva √† forma√ß√£o de uma resposta imune protetora por alguns dos camundongos nude.Athymic BALB/c (Nu/Nu) mice died at 7-13 days after inoculation (DAI) of Plasmodium berghei NK65, whereas their heterozygous (Nu/+) littermates died at 7-8 DAI. Nude (Nu/Nu) mice, reconstituted with 2 x 10(7) splenocytes from uninfected heterozygous (Nu/+) littermates at 20 days before parasite inoculation (DBI), died about 2 days earlier than control nude mice; nude mice reconstituted at 10 or 2 DBI lived 2 to 4 days longer than control nudes; and nude mice reconstituted 2 DAI lived even longer and some survived. These findings indicate that P. berghei NK65 induces at least two T-cell dependent immune phenomena, one suppressive and the other stimulatory. Reconstitution of nude mice with T-cells from BALB/c (Nu/+) mice appeared to reduce or bypass suppressive T-cell activities which allowed the formation of a protective immune response by some of the nude mice

    Swine in Confinement - Feeding

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    It\u27s no news that hog feeding has moved out of the slopping stage. With the movement from pasture to houses and the shift from a small number of slop-fed hogs to larger scale production, swine producers soon learned that when swine are confined without vegetation, more care had to be taken with rations. And, with feed costs accounting for two-thirds to nearly nine-tenths of the total production cost, no wonder so much attention has been paid to rations, feeds, and feeding

    A natural stochastic extension of the sandpile model on a graph

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    We introduce a new model of a stochastic sandpile on a graph GG containing a sink. When unstable, a site sends one grain to each of its neighbours independently with probability p‚ąą(0,1]p \in (0,1]. For p=1p=1, this coincides with the standard Abelian sandpile model. In general, for p‚ąą(0,1)p\in(0,1), the set of recurrent configurations of this sandpile model is different from that of the Abelian sandpile model. We give a characterisation of this set in terms of orientations of the graph GG. We also define the lacking polynomial LGL_G as the generating function counting this set according to the number of grains, and show that this polynomial satisfies a recurrence which resembles that of the Tutte polynomial

    Simulation of Heavily Irradiated Silicon Pixel Sensors and Comparison with Test Beam Measurements

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    Charge collection measurements performed on heavily irradiated p-spray DOFZ pixel sensors with a grazing angle hadron beam provide a sensitive determination of the electric field within the detectors. The data are compared with a complete charge transport simulation of the sensor which includes signal trapping and charge induction effects. A linearly varying electric field based upon the standard picture of a constant type-inverted effective doping density is inconsistent with the data. A two-trap double junction model implemented in the ISE TCAD software can be tuned to produce a doubly-peaked electric field which describes the data reasonably well. The modeled field differs somewhat from previous determinations based upon the transient current technique. The model can also account for the level of charge trapping observed in the data.Comment: 8 pages, 11 figures. Talk presented at the 2004 IEEE Nuclear Science Symposium, October 18-21, Rome, Italy. Submitted to IEEE Transactions on Nuclear Scienc

    Poet: Product-oriented Video Captioner for E-commerce

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    In e-commerce, a growing number of user-generated videos are used for product promotion. How to generate video descriptions that narrate the user-preferred product characteristics depicted in the video is vital for successful promoting. Traditional video captioning methods, which focus on routinely describing what exists and happens in a video, are not amenable for product-oriented video captioning. To address this problem, we propose a product-oriented video captioner framework, abbreviated as Poet. Poet firstly represents the videos as product-oriented spatial-temporal graphs. Then, based on the aspects of the video-associated product, we perform knowledge-enhanced spatial-temporal inference on those graphs for capturing the dynamic change of fine-grained product-part characteristics. The knowledge leveraging module in Poet differs from the traditional design by performing knowledge filtering and dynamic memory modeling. We show that Poet achieves consistent performance improvement over previous methods concerning generation quality, product aspects capturing, and lexical diversity. Experiments are performed on two product-oriented video captioning datasets, buyer-generated fashion video dataset (BFVD) and fan-generated fashion video dataset (FFVD), collected from Mobile Taobao. We will release the desensitized datasets to promote further investigations on both video captioning and general video analysis problems.Comment: 10 pages, 3 figures, to appear in ACM MM 2020 proceeding
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