69 research outputs found

    Misconceptions of science teacher candidates about heat and temperature

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    3rd World Conference on Educational Sciences (WCES) -- FEB 03-07, 2011 -- Bahcesehir Univ, Istanbul, TURKEYWOS: 000466750602149In this study, the misconceptions that the students have about heat and temperature and the reasons behind it have been focused. Members of study group include 60 second grade students of the Faculty of Education of Ahi Evran University during 2009-2010 school year. Multiple-choice tests have been used to be able find out misconceptions. In this test, also entitled as "Diagnostic Test", there is a space where students are expected to write why they have chosen that particular option after a number of items including the right answer along with confounding options. In addition, the misconceptions of teacher candidates have been put forth as an outcome of the analysis of data about heat and temperature. (C) 2011 Published by Elsevier Ltd.Ankara Univ, Near E Uni

    Search for CPCP violation in D0^0\to KS0^0_\mathrm{S}KS0^0_\mathrm{S} decays in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceA search is reported for charge-parity D0^0\to KS0^0_\mathrm{S}KS0^0_\mathrm{S}CPCP violation in D0^0\to KS0^0_\mathrm{S}KS0^0_\mathrm{S} decays, using data collected in proton-proton collisions at s\sqrt{s} = 13 TeV recorded by the CMS experiment in 2018. The analysis uses a dedicated data set that corresponds to an integrated luminosity of 41.6 fb1^{-1}, which consists of about 10 billion events containing a pair of ẖadrons, nearly all of which decay to charm hadrons. The flavor of the neutral D meson is determined by the pion charge in the reconstructed decays D+^{*+}\to D0π+^0\pi^+ and D^{*-}\to D0π^0\pi^-. The D0^0\to KS0^0_\mathrm{S}KS0^0_\mathrm{S}CPCP asymmetry in D0^0\to KS0^0_\mathrm{S}KS0^0_\mathrm{S} is measured to be ACPA_{CP}( KS0^0_\mathrm{S}KS0^0_\mathrm{S}) = (6.2 ±\pm 3.0 ±\pm 0.2 ±\pm 0.8)%, where the three uncertainties represent the statistical uncertainty, the systematic uncertainty, and the uncertainty in the measurement of the D0^0 \to KS0^0_\mathrm{S}KS0^0_\mathrm{S} CPCP asymmetry in the D0^0 \to KS0π+π^0_\mathrm{S}\pi^+\pi^- decay. This is the first D0^0 \to KS0^0_\mathrm{S}KS0^0_\mathrm{S} CPCP asymmetry measurement by CMS in the charm sector as well as the first to utilize a fully hadronic final state

    Search for the Z boson decay to ττμμ\tau\tau\mu\mu in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceThe first search for the Z boson decay to ττμμ\tau\tau\mu\mu at the CERN LHC is presented, based on data collected by the CMS experiment at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 138 fb1^{-1}. The data are compatible with the predicted background. For the first time, an upper limit at the 95% confidence level of 6.9 times the standard model expectation is placed on the ratio of the Z \to ττμμ\tau\tau\mu\mu to Z \to 4μ\mu branching fractions. Limits are also placed on the six flavor-conserving four-lepton effective-field-theory operators involving two muons and two tau leptons, for the first time testing all such operators

    Searches for Higgs boson production through decays of heavy resonances

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    The discovery of the Higgs boson has led to new possible signatures for heavy resonance searches at the LHC. Since then, search channels including at least one Higgs boson plus another particle have formed an important part of the program of new physics searches. In this report, the status of these searches by the CMS Collaboration is reviewed. Searches are discussed for resonances decaying to two Higgs bosons, a Higgs and a vector boson, or a Higgs boson and another new resonance, with proton-proton collision data collected at s= \sqrt{s}= 13 TeV in the years 2016-2018. A combination of the results of these searches is presented together with constraints on different beyond-the-standard model scenarios, including scenarios with extended Higgs sectors, heavy vector bosons and extra dimensions. Studies are shown for the first time by CMS on the validity of the narrow-width approximation in searches for the resonant production of a pair of Higgs bosons. The potential for a discovery at the High Luminosity LHC is also discussed.The discovery of the Higgs boson has led to new possible signatures for heavy resonance searches at the LHC. Since then, search channels including at least one Higgs boson plus another particle have formed an important part of the program of new physics searches. In this report, the status of these searches by the CMS Collaboration is reviewed. Searches are discussed for resonances decaying to two Higgs bosons, a Higgs and a vector boson, or a Higgs boson and another new resonance, with proton-proton collision data collected at s\sqrt{s} = 13 TeV in the years 2016-2018. A combination of the results of these searches is presented together with constraints on different beyond-the-standard model scenarios, including scenarios with extended Higgs sectors, heavy vector bosons and extra dimensions. Studies are shown for the first time by CMS on the validity of the narrow-width approximation in searches for the resonant production of a pair of Higgs bosons. The potential for a discovery at the High Luminosity LHC is also discussed

    The CMS Statistical Analysis and Combination Tool: COMBINE

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    International audienceThis paper describes the COMBINE software package used for statistical analyses by the CMS Collaboration. The package, originally designed to perform searches for a Higgs boson and the combined analysis of those searches, has evolved to become the statistical analysis tool presently used in the majority of measurements and searches performed by the CMS Collaboration. It is not specific to the CMS experiment, and this paper is intended to serve as a reference for users outside of the CMS Collaboration, providing an outline of the most salient features and capabilities. Readers are provided with the possibility to run COMBINE and reproduce examples provided in this paper using a publicly available container image. Since the package is constantly evolving to meet the demands of ever-increasing data sets and analysis sophistication, this paper cannot cover all details of COMBINE. However, the online documentation referenced within this paper provides an up-to-date and complete user guide

    Dark sector searches with the CMS experiment

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    Astrophysical observations provide compelling evidence for gravitationally interacting dark matter in the universe that cannot be explained by the standard model of particle physics. The extraordinary amount of data from the CERN LHC presents a unique opportunity to shed light on the nature of dark matter at unprecedented collision energies. This Report comprehensively reviews the most recent searches with the CMS experiment for particles and interactions belonging to a dark sector and for dark-sector mediators. Models with invisible massive particles are probed by searches for signatures of missing transverse momentum recoiling against visible standard model particles. Searches for mediators are also conducted via fully visible final states. The results of these searches are compared with those obtained from direct-detection experiments. Searches for alternative scenarios predicting more complex dark sectors with multiple new particles and new forces are also presented. Many of these models include long-lived particles, which could manifest themselves with striking unconventional signatures with relatively small amounts of background. Searches for such particles are discussed and their impact on dark-sector scenarios is evaluated. Many results and interpretations have been newly obtained for this Report.Astrophysical observations provide compelling evidence for gravitationally interacting dark matter in the universe that cannot be explained by the standard model of particle physics. The extraordinary amount of data from the CERN LHC presents a unique opportunity to shed light on the nature of dark matter at unprecedented collision energies. This Report comprehensively reviews the most recent searches with the CMS experiment for particles and interactions belonging to a dark sector and for dark-sector mediators. Models with invisible massive particles are probed by searches for signatures of missing transverse momentum recoiling against visible standard model particles. Searches for mediators are also conducted via fully visible final states. The results of these searches are compared with those obtained from direct-detection experiments. Searches for alternative scenarios predicting more complex dark sectors with multiple new particles and new forces are also presented. Many of these models include long-lived particles, which could manifest themselves with striking unconventional signatures with relatively small amounts of background. Searches for such particles are discussed and their impact on dark-sector scenarios is evaluated. Many results and interpretations have been newly obtained for this Report

    Observation of the Ξb\Xi^-_\mathrm{b}\toψ\psi(2S)Ξ\Xi^- decay and studies of the Ξb0\Xi_\mathrm{b}^{\ast{}0} baryon in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceThe first observation of the decay Ξb\Xi^-_\mathrm{b}\toψ\psi(2S)Ξ\Xi^- and measurement of the branching ratio of Ξb\Xi^-_\mathrm{b}\toψ\psi(2S)Ξ\Xi^- to Ξb\Xi^-_\mathrm{b}\to J/ψ\psiΞ\Xi^- are presented. The J/ψ\psi and ψ\psi(2S) mesons are reconstructed using their dimuon decay modes. The results are based on proton-proton colliding beam data from the LHC collected by the CMS experiment at s\sqrt{s} = 13 TeV in 2016-2018, corresponding to an integrated luminosity of 140 fb1^{-1}. The branching fraction ratio is measured to be B\mathcal{B}(Ξb\Xi^-_\mathrm{b}\toψ\psi(2S)Ξ\Xi^-)/B\mathcal{B}(Ξb\Xi^-_\mathrm{b}\to J/ψ\psiΞ\Xi^-) = 0.840.19+0.21^{+0.21}_{-0.19} (stat) ±\pm 0.10 (syst) ±\pm 0.02 (B\mathcal{B}), where the last uncertainty comes from the uncertainties in the branching fractions of the charmonium states. New measurements of the Ξb0\Xi_\mathrm{b}^{\ast{}0} baryon mass and natural width are also presented, using the Ξbπ+\Xi_\mathrm{b}^-\pi^+ final state, where the Ξb\Xi^-_\mathrm{b} baryon is reconstructed through the decays J/ψΞ\psi \Xi^-, ψ\psi(2S)Ξ\Xi^-, J/ψΛ\psi \LambdaK^-, and J/ψΣ0\psi \Sigma^0K^-. Finally, the fraction of the Ξb\Xi^-_\mathrm{b} baryons produced from Ξb0\Xi_\mathrm{b}^{\ast{}0} decays is determined

    Search for the decay of the Higgs boson to a pair of light pseudoscalar bosons in the final state with four bottom quarks in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceA search is presented for the decay of the 125 GeV Higgs boson (H) to a pair of new light pseudoscalar bosons (a), followed by the prompt decay of each a boson to a bottom quark-antiquark pair, H \to aa \tobbˉbbˉ\mathrm{b\bar{b}b\bar{b}}. The analysis is performed using a data sample of proton-proton collisions collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb1^{-1}. To reduce the background from standard model processes, the search requires the Higgs boson to be produced in association with a leptonically decaying W or Z boson. The analysis probes the production of new light bosons in a 15 <\ltmam_\mathrm{a}<\lt 60 GeV mass range. Assuming the standard model predictions for the Higgs boson production cross sections for pp \to WH and ZH, model independent upper limits at 95% confidence level are derived for the branching fraction B\mathcal{B}(H \to aa \to bbˉbbˉ\mathrm{b\bar{b}b\bar{b}}). The combined WH and ZH observed upper limit on the branching fraction ranges from 1.10 for ma=m_\mathrm{a} = 20 GeV to 0.36 for ma=m_\mathrm{a} = 60 GeV, complementing other measurements in the μμττ\mu\mu\tau\tau, ττττ\tau\tau\tau\tau and bb\ell\ell (=\ell= μ\mu,τ\tau) channels

    Observation of the J/ψ\psi \to μ+μμ+μ\mu^+\mu^-\mu^+\mu^- decay in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceThe J/ψ\psi\toμ+μμ+μ\mu^+\mu^-\mu^+\mu^- decay has been observed with a statistical significance in excess of five standard deviations. The analysis is based on an event sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS experiment in 2018 and corresponding to an integrated luminosity of 33.6 fb1{-1}. Normalizing to the J/ψ\psi\toμ+μ\mu^+\mu^- decay mode leads to a branching fraction [10.12.7+3.3^{+3.3}_{-2.7} (stat) ±\pm 0.4 (syst) ]×\times 107^{-7}, a value that is consistent with the standard model prediction

    Search for new resonances decaying to pairs of merged diphotons in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceA search is presented for an extended Higgs sector with two new particles, X and ϕ\phi, in the process X \toϕϕ\phi\phi\to(γγ)(γγ)(\gamma\gamma)(\gamma\gamma). Novel neural networks classify events with diphotons that are merged and determine the diphoton masses. The search uses LHC proton-proton collision data at s\sqrt{s} = 13 TeV collected with the CMS detector, corresponding to an integrated luminosity of 138 fb1^{-1}. No evidence of such resonances is seen. Upper limits are set on the production cross section versus the resonance masses, representing the most sensitive search in this channel
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