1,410 research outputs found

    Study of Standard Model Scalar Production in Bosonic Decay Channels in CMS

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    The status of the Standard Model Scalar Boson search in the bosonic decay channels at the CMS experiment at the LHC is presented. The results are based on proton-proton collisions data corresponding to integrated luminosities of up to 5.1 fb-1 at sqrt{s} = 7 TeV and 19.6 fb-1 at sqrt{s} = 8 TeV. The observation of a new boson at a mass near 126 GeV is confirmed by the analysis of the new data and first measurements of the boson properties are shown.Comment: 12 pages, 20 figures, proceedings of the talk given in the Rencontres de Moriond Electroweak Interactions and Unified theories 201

    Search for Anomalous Production of Multilepton Events in pp̅ Collisions at √s=1.96  TeV

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    We report a search for the anomalous production of events with multiple charged leptons in pp̄ collisions at s=1.96TeV using a data sample corresponding to an integrated luminosity of 346pb-1 collected by the CDFII detector at the Fermilab Tevatron. The search is divided into three-lepton and four-or-more-lepton data samples. We observe six events in the three-lepton sample and zero events in the 4-lepton sample. Both numbers of events are consistent with standard model background expectations. Within the framework of an R-parity-violating supergravity model, the results are interpreted as mass limits on the lightest neutralino (χ 10) and chargino (χ1±) particles. For one particular choice of model parameters, the limits are M(χ10)>110GeV/c2 and M(χ1±)>203GeV/c2 at 95% confidence level; the variation of these mass limits with model parameters is presented. © 2007 The American Physical Society.This work was supported by the U.S. Department of Energy and National Science Foundation; the Italian Istituto Nazionale di Fisica Nucleare; the Ministry of Education, Culture, Sports, Science and Technology of Japan; the Natural Sciences and Engineering Research Council of Canada; the National Science Council of the Republic of China; the Swiss National Science Foundation; the A. P. Sloan Foundation; the Bundesministerium fušr Bildung und Forschung, Germany; the Korean Science and Engineering Foundation and the Korean Research Foundation; the Particle Physics and Astronomy Research Council and the Royal Society, UK; the Russian Foundation for Basic Research; the ComisioÂŽn Interministerial de Ciencia y TecnologıŽa, Spain; in part by the European Community’s Human Potential Programme under Contract No. HPRN-CT-2002-00292; and the Academy of Finland.Peer Reviewe

    Measurement of the ratio of branching fractions B(B±→J/ ψπ±)/B(B±→J/ψK±)

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    We report a measurement of the ratio of branching fractions of the decays B±→J/ψπ± and B±→J/ψK± using the CDF II detector at the Fermilab Tevatron Collider. The signal from the Cabbibo-suppressed B±→J/ψπ± decay is separated from B±→J/ψK± using the B±→J/ψK± invariant mass distribution and the kinematical differences of the hadron track in the two decay modes. From a sample of 220pb-1 of pp̄ collisions at s=1.96TeV, we observe 91±15 B±→J/ψπ± events together with 1883±34 B±→J/ψK± events. The ratio of branching fractions is found to be B(B±→J/ψπ±)/ B(B±→J/ψK±)=(4.86±0.82(stat)±0.15(syst))%. © 2009 The American Physical Society.This work was supported by the U.S. Department of Energy and the National Science Foundation; the Italian Istituto Nazionale di Fisica Nucleare; the Ministry of Education, Culture, Sports, Science and Technology of Japan; the Natural Sciences and Engineering Research Council of Canada; the National Science Council of the Republic of China; the Swiss National Science Foundation; the A. P. Sloan Foundation; the Bundesministerium fĂŒr Bildung und Forschung, Germany; the Korean Science and Engineering Foundation and the Korean Research Foundation; the Particle Physics and Astronomy Research Council and the Royal Society, UK; the Russian Foundation for Basic Research; the ComisiĂłn Interministerial de Ciencia y TecnologĂ­a, Spain; in part by the European Community’s Human Potential Programme under Contract No. HPRNCT-2002-00292; and the Academy of Finland

    Measurements of CP-conserving trilinear gauge boson couplings WWV (V ≡ γ,Z) in e+e− collisions at LEP2

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    The data taken by DELPHI at centre-of-mass energies between 189 and 209 GeV are used to place limits on the CP-conserving trilinear gauge boson couplings ΔgZ1 , λ Îł and ΔÎș Îł associated to W + W − and single W production at LEP2. Using data from the jj ℓ Îœ, jjjj, jjX and ℓ X final states, where j, ℓ and X represent a jet, a lepton and missing four-momentum, respectively, the following limits are set on the couplings when one parameter is allowed to vary and the others are set to their Standard Model values of zero: ΔgZ1=−0.025+0.033−0.030,\vskip6ptλγ=0.002+0.035−0.035and\vskip6ptΔÎșÎł=0.024+0.077−0.081. Results are also presented when two or three parameters are allowed to vary. All observations are consistent with the predictions of the Standard Model and supersede the previous results on these gauge coupling parameters published by DELPHI

    Search for single top quark production via contact interactions at LEP2

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    Single top quark production via four-fermion contact interactions associated to flavour-changing neutral currents was searched for in data taken by the DELPHI detector at LEP2. The data were accumulated at centre-ofmass energies ranging from 189 to 209 GeV, with an integrated luminosity of 598.1 pb?1. No evidence for a signal was found. Limits on the energy scale ?, were set for scalar-, vector- and tensor-like coupling scenarios.We are greatly indebted to our technical collaborators, to the members of the CERN-SL Division for the excellent performance of the LEP collider, and to the funding agencies for their support in building and operating the DELPHI detector. We acknowledge in particular the support of Austrian Federal Ministry of Education, Science and Culture, GZ 616.364/2-III/2a/98, FNRS–FWO, Flanders Institute to encourage scientific and technological research in the industry (IWT) and Belgian Federal Office for Scientific, Technical and Cultural affairs (OSTC), Belgium, FINEP, CNPq, CAPES, FUJB and FAPERJ, Brazil, Ministry of Education of the Czech Republic, project LC527, Academy of Sciences of the Czech Republic, project AV0Z10100502, Commission of the European Communities (DG XII), Direction des Sciences de la Matiere, CEA, France, ` Bundesministerium fur Bildung, Wissenschaft, Forschung und Tech- š nologie, Germany, General Secretariat for Research and Technology, Greece, National Science Foundation (NWO) and Foundation for Research on Matter (FOM), The Netherlands, Norwegian Research Council, State Committee for Scientific Research, Poland, SPUB-M/CERN/PO3/ DZ296/2000, SPUB-M/CERN/PO3/DZ297/2000, 2P03B 104 19 and 2P03B 69 23(2002-2004), FCT—Fundação para a CiĂȘncia e Tecnologia, Portugal, Vedecka grantova agentura MS SR, Slovakia, Nr. 95/5195/134, Ministry of Science and Technology of the Republic of Slovenia, CICYT, Spain, AEN99-0950 and AEN99-0761, The Swedish Research Council, The Science and Technology Facilities Council, UK, Department of Energy, USA, DE-FG02-01ER41155, EEC RTN contract HPRN-CT-00292-2002

    A study of the b-quark fragmentation function with the DELPHI detector at LEP I and an averaged distribution obtained at the Z Pole

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    The nature of b-quark jet hadronisation has been investigated using data taken at the Z peak by the DELPHI detector at LEP. Two complementary methods are used to reconstruct the energy of weakly decaying b-hadrons, Eweak B . The average value of xweak B = Eweak B /Ebeam is measured to be 0.699 ± 0.011. The resulting xweak B distribution is then analysed in the framework of two choices for the perturbative contribution (parton shower and Next to Leading Log QCD calculation) in order to extract measurements of the non-perturbative contribution to be used in studies of bhadron production in other experimental environments than LEP. In the parton shower framework, data favour the Lund model ansatz and corresponding values of its parameters have been determined within PYTHIA 6.156 from DELPHI data: a = 1.84+0.23 ?0.21 and b = 0.642+0.073 ?0.063 GeV?2, with a correlation factor ? = 92.2%. Combining the data on the b-quark fragmentation distributions with those obtained at the Z peak by ALEPH, OPAL and SLD, the average value of xweak B is found to be 0.7092 ± 0.0025 and the non-perturbative fragmentation component is extracted. Using the combined distribution, a better determination of the Lund parameters is also obtained: a = 1.48+0.11 ?0.10 and b = 0.509+0.024 ?0.023 GeV?2, with a correlation factor ? = 92.6%

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

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    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð„with constraintsð ð ð„ „ ðandðŽð„ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

    MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV

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    Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe

    Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

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    A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

    Measurement of prompt open-charm production cross sections in proton-proton collisions at root s=13 TeV

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    The production cross sections for prompt open-charm mesons in proton-proton collisions at a center-of-mass energy of 13TeV are reported. The measurement is performed using a data sample collected by the CMS experiment corresponding to an integrated luminosity of 29 nb(-1). The differential production cross sections of the D*(+/-), D-+/-, and D-0 ((D) over bar (0)) mesons are presented in ranges of transverse momentum and pseudorapidity 4 < p(T) < 100 GeV and vertical bar eta vertical bar < 2.1, respectively. The results are compared to several theoretical calculations and to previous measurements.Peer reviewe
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