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399 Research products, page 1 of 40

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  • Open Access
    Authors: 
    J. P. Lees; V. Poireau; V. Tisserand; E. Grauges; A. Palano; D. N. Brown; Yu. G. Kolomensky; Herbert Koch; T. Schroeder; C. Hearty; +192 more
    Publisher: American Physical Society (APS)
    Project: NSERC

    We measure the $D^0 - {\bar{D}}^0$ mixing parameters using a time-dependent amplitude analysis of the decay $D^0\to\pi^+\pi^-\pi^0$. The data were recorded with the BABAR detector at center-of-mass energies at and near the $\Upsilon(4S)$ resonance, and correspond to an integrated luminosity of approximately 468.1 ${\rm fb}^{-1}$. The neutral $D$ meson candidates are selected from $D^{*}(2010)^+\to D^0 \pi_s^+$ decays where the flavor at the production is identified by the charge of the low momentum pion, $\pi_s^+$. The measured mixing parameters are $x = (1.5\pm1.2\pm0.6) \%$ and $y = (0.2\pm0.9\pm0.5) \%$, where the quoted uncertainties are statistical and systematic, respectively.

  • Open Access
    Authors: 
    Georges Aad; Bobby Samir Acharya; Leszek Adamczyk; Jahred Adelman; Stefanie Adomeit; Tim Adye; Tatjana Agatonovic-Jovin; Faig Ahmadov; Giulio Aielli; Gian Luigi Alberghi; +592 more
    Publisher: American Physical Society (APS)
    Project: NSERC

    Many extensions of the Standard Model posit the existence of heavy particles with long lifetimes. This article presents the results of a search for events containing at least one long-lived particle that decays at a significant distance from its production point into two leptons or into five or more charged particles. This analysis uses a data sample of proton-proton collisions at root s = 8 TeV corresponding to an integrated luminosity of 20.3 fb(-1) collected in 2012 by the ATLAS detector operating at the Large Hadron Collider. No events are observed in any of the signal regions, and limits are set on model parameters within supersymmetric scenarios involving R-parity violation, split supersymmetry, and gauge mediation. In some of the search channels, the trigger and search strategy are based only on the decay products of individual long-lived particles, irrespective of the rest of the event. In these cases, the provided limits can easily be reinterpreted in different scenarios.

  • Open Access
    Authors: 
    V. Poireau; V. Tisserand; E. Grauges; A. Palano; G. Eigen; D. N. Brown; Yu G. Kolomensky; M. Fritsch; Herbert Koch; C. Hearty; +191 more
    Publisher: American Physical Society (APS)
    Project: NSERC

    We measure the mass difference, Δm_{+}, between the D^{*}(2010)^{+} and the D^{+} using the decay chain D^{*}(2010)^{+}→D^{+}π^{0} with D^{+}→K^{-}π^{+}π^{+}. The data were recorded with the BABAR detector at center-of-mass energies at and near the ϒ(4S) resonance, and correspond to an integrated luminosity of approximately 468 fb^{-1}. We measure Δm_{+}=(140 601.0±6.8[stat]±12.9[syst]) keV. We combine this result with a previous BABAR measurement of Δm_{0}≡m(D^{*}(2010)^{+})-m(D^{0}) to obtain Δm_{D}=m(D^{+})-m(D^{0})=(4824.9±6.8[stat]±12.9[syst]) keV. These results are compatible with and approximately five times more precise than the Particle Data Group averages.

  • Open Access English
    Authors: 
    Gerold Busch; Bernd Husemann; I. Smirnova-Pinchukova; Andreas Eckart; Stefi A. Baum; Francoise Combes; Scott M. Croom; Timothy A. Davis; Nastaran Fazeli; C. Fischer; +11 more
    Publisher: American Astronomical Society
    Countries: Spain, France, Italy, Spain
    Project: NSERC

    We report spatially resolved [C ii] λ158 μm observations of HE 0433-1028, which is the first detection of a nearby luminous active galactic nucleus (AGN; redshift 0.0355) with the Field-Imaging Far-Infrared Line Spectrometer (FIFI-LS) on board the airborne Stratospheric Observatory For Infrared Astronomy (SOFIA). We compare the spatially resolved star formation tracers [C ii], as provided by our SOFIA observations, and Hα from the Multi Unit Spectroscopic Explorer (MUSE) optical integral-field spectroscopy. We find that the [C ii] emission is mainly matching the extended star formation as traced by the extinction-corrected Hα line emission but some additional flux is present. While a larger sample is needed to statistically confirm our findings and investigate possible dependencies on AGN luminosity and star formation rate, our study underlines the necessity of collecting a spatially resolved optical-far-infrared data set for nearby AGNs, and shows that it is technically feasible to collect such data sets with FIFI-LS on board SOFIA. © 2018. The American Astronomical Society. All rights reserved. Based in part on observations made with the NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA). SOFIA is jointly operated by the Universities Space Research Association, Inc. (USRA), under NASA contract NAS2-97001, and the Deutsches SOFIA Institut (DSI) under DLR contract 50 OK 0901 to the University of Stuttgart. We thank the anonymous referee for a constructive report that helped to clarify the manuscript. This work was supported by the Deutsche Forschungsgemeinschaft (DFG) via SFB 956, subprojects A2, and A6. The work of S.B. and C.O. was supported by NSERC (Natural Sciences and Engineering Research Council of Canada). M.G. is supported by NASA through Einstein Postdoctoral Fellowship Award No. PF5-160137 issued by the Chandra X-ray Observatory Center, which is operated by the SAO for and on behalf of NASA under contract NAS8-03060. Support for this work was also provided by Chandra grant GO7-18121X. M.K. acknowledges support by DLR 50OR1802. M.P.T. acknowledges support from the Spanish MINECO through grants AYA2012-38491-C02-02 and AYA2015-63939-C2-1-P. Peer reviewed

  • Open Access
    Authors: 
    G. Aad; B. Abbott; J. Abdallah; A.A. Abdelalim; A. Abdesselam; O. Abdinov; B. Abi; M. Abolins; H. Abramowicz; H. Abreu; +191 more
    Publisher: Elsevier BV
    Project: NSERC

    The cross section for the production of W bosons with subsequent decay W to tau nu is measured with the ATLAS detector at the LHC. The analysis is based on a data sample that was recorded in 2010 at a proton-proton center-of-mass energy of sqrt(s) = 7 TeV and corresponds to an integrated luminosity of 34 pb^-1. The cross section is measured in a region of high detector acceptance and then extrapolated to the full phase space. The product of the total W production cross section and the W to tau nu branching ratio is measured to be 11.1 +/- 0.3 (stat) +/- 1.7 (syst) +/- 0.4 (lumi) nb.

  • Open Access English
    Authors: 
    Aad, G; Abbott, B; Abdallah, J; Abdelalim, AA; Abdesselam, A; Abdinovi, O; Abi, B; Abolins, M; Abramowicz, H; Abreu, H; +191 more
    Countries: Spain, Serbia, United Kingdom, France, Turkey, France, Italy, France, Italy, Germany ...
    Project: NSERC

    A search for the Standard Model Higgs boson in the two photon decay channel is reported, using 1.08 fb−11.08 fb[superscript −1] of proton–proton collision data at a centre-of-mass energy of 7 TeV recorded by the ATLAS detector. No significant excess is observed in the investigated mass range of 110–150 GeV. Upper limits on the cross-section times branching ratio of between 2.0 and 5.8 times the Standard Model prediction are derived for this mass range. National Science Foundation (U.S.) United States. Dept. of Energy Brookhaven National Laboratory

  • Open Access
    Authors: 
    G. Aad; B. Abbott; J. Abdallah; S. Abdel Khalek; A.A. Abdelalim; O. Abdinov; B. Abi; M. Abolins; O.S. AbouZeid; H. Abramowicz; +191 more
    Publisher: Elsevier BV
    Project: NSERC

    Measurement of the top quark pair cross section with ATLAS in pp collisions at root s=7 TeV using final states with an electron or a muon and a hadronically decaying tau lepton

  • Open Access English
    Authors: 
    V. Poireau; V. Tisserand; E. Grauges; A. Palano; M. Pappagallo; B. Stugu; D. N. Brown; L. T. Kerth; Yu. G. Kolomensky; D. J. Asgeirsson; +202 more
    Publisher: HAL CCSD
    Countries: Italy, United States, Italy, Italy, Netherlands, Italy, France
    Project: NSERC

    See paper for full list of authors - 7 pages, 5 postscript figures, submitted to Phys. Rev. Lett; Recent astrophysical and terrestrial experiments have motivated the proposal of a dark sector with GeV-scale gauge boson force carriers and new Higgs bosons. We present a search for a dark Higgs boson using 516 fb-1 of data collected with the BABAR detector. We do not observe a significant signal and we set 90% confidence level upper limits on the product of the Standard Model-dark sector mixing angle and the dark sector coupling constant.

  • Open Access
    Authors: 
    K. Abe; J. Amey; M. Antonova; Akitaka Ariga; Y. Ashida; D. Autiero; S. Ban; M. Barbi; Gareth J. Barker; G.D. Barr; +195 more
    Publisher: American Physical Society (APS)
    Project: NSERC , EC | JENNIFER (644294)

    We report measurements by the T2K experiment of the parameters $\theta_{23}$ and $\Delta m^{2}_{32}$ governing the disappearance of muon neutrinos and antineutrinos in the three flavor neutrino oscillation model. Utilizing the ability of the experiment to run with either a mainly neutrino or a mainly antineutrino beam, the parameters are measured separately for neutrinos and antineutrinos. Using $7.482 \times 10^{20}$ POT in neutrino running mode and $7.471 \times 10^{20}$ POT in antineutrino mode, T2K obtained, $\sin^{2}(\theta_{23})=0.51^{+0.08}_{-0.07}$ and $\Delta m^{2}_{32} = 2.53^{+0.15}_{-0.13} \times 10^{-3}$eV$^{2}$/c$^{4}$ for neutrinos, and $\sin^{2}({\overline{\theta}}_{23})=0.42^{+0.25}_{-0.07}$ and ${\Delta\overline{m}^2}_{32} = 2.55^{+0.33}_{-0.27} \times 10^{-3}$eV$^{2}$/c$^{4}$ for antineutrinos (assuming normal mass ordering). No significant differences between the values of the parameters describing the disappearance of muon neutrinos and antineutrinos were observed.

  • Open Access
    Authors: 
    A. A. Abdelalim; Jahred Adelman; J. Albert; Theodoros Alexopoulos; G. Anders; M. L. Andrieux; Francis Anghinolfi; Alberto Annovi; Giacomo Artoni; A. Astbury; +188 more
    Publisher: Elsevier BV
    Project: NSERC

    This Letter reports a measurement of the W W production cross section in root s = 7 TeV pp collisions using data corresponding to an integrated luminosity of 1.02 fb(-1) collected with the ATLAS de ...

search
Include:
The following results are related to Canada. Are you interested to view more results? Visit OpenAIRE - Explore.
399 Research products, page 1 of 40
  • Open Access
    Authors: 
    J. P. Lees; V. Poireau; V. Tisserand; E. Grauges; A. Palano; D. N. Brown; Yu. G. Kolomensky; Herbert Koch; T. Schroeder; C. Hearty; +192 more
    Publisher: American Physical Society (APS)
    Project: NSERC

    We measure the $D^0 - {\bar{D}}^0$ mixing parameters using a time-dependent amplitude analysis of the decay $D^0\to\pi^+\pi^-\pi^0$. The data were recorded with the BABAR detector at center-of-mass energies at and near the $\Upsilon(4S)$ resonance, and correspond to an integrated luminosity of approximately 468.1 ${\rm fb}^{-1}$. The neutral $D$ meson candidates are selected from $D^{*}(2010)^+\to D^0 \pi_s^+$ decays where the flavor at the production is identified by the charge of the low momentum pion, $\pi_s^+$. The measured mixing parameters are $x = (1.5\pm1.2\pm0.6) \%$ and $y = (0.2\pm0.9\pm0.5) \%$, where the quoted uncertainties are statistical and systematic, respectively.

  • Open Access
    Authors: 
    Georges Aad; Bobby Samir Acharya; Leszek Adamczyk; Jahred Adelman; Stefanie Adomeit; Tim Adye; Tatjana Agatonovic-Jovin; Faig Ahmadov; Giulio Aielli; Gian Luigi Alberghi; +592 more
    Publisher: American Physical Society (APS)
    Project: NSERC

    Many extensions of the Standard Model posit the existence of heavy particles with long lifetimes. This article presents the results of a search for events containing at least one long-lived particle that decays at a significant distance from its production point into two leptons or into five or more charged particles. This analysis uses a data sample of proton-proton collisions at root s = 8 TeV corresponding to an integrated luminosity of 20.3 fb(-1) collected in 2012 by the ATLAS detector operating at the Large Hadron Collider. No events are observed in any of the signal regions, and limits are set on model parameters within supersymmetric scenarios involving R-parity violation, split supersymmetry, and gauge mediation. In some of the search channels, the trigger and search strategy are based only on the decay products of individual long-lived particles, irrespective of the rest of the event. In these cases, the provided limits can easily be reinterpreted in different scenarios.

  • Open Access
    Authors: 
    V. Poireau; V. Tisserand; E. Grauges; A. Palano; G. Eigen; D. N. Brown; Yu G. Kolomensky; M. Fritsch; Herbert Koch; C. Hearty; +191 more
    Publisher: American Physical Society (APS)
    Project: NSERC

    We measure the mass difference, Δm_{+}, between the D^{*}(2010)^{+} and the D^{+} using the decay chain D^{*}(2010)^{+}→D^{+}π^{0} with D^{+}→K^{-}π^{+}π^{+}. The data were recorded with the BABAR detector at center-of-mass energies at and near the ϒ(4S) resonance, and correspond to an integrated luminosity of approximately 468 fb^{-1}. We measure Δm_{+}=(140 601.0±6.8[stat]±12.9[syst]) keV. We combine this result with a previous BABAR measurement of Δm_{0}≡m(D^{*}(2010)^{+})-m(D^{0}) to obtain Δm_{D}=m(D^{+})-m(D^{0})=(4824.9±6.8[stat]±12.9[syst]) keV. These results are compatible with and approximately five times more precise than the Particle Data Group averages.

  • Open Access English
    Authors: 
    Gerold Busch; Bernd Husemann; I. Smirnova-Pinchukova; Andreas Eckart; Stefi A. Baum; Francoise Combes; Scott M. Croom; Timothy A. Davis; Nastaran Fazeli; C. Fischer; +11 more
    Publisher: American Astronomical Society
    Countries: Spain, France, Italy, Spain
    Project: NSERC

    We report spatially resolved [C ii] λ158 μm observations of HE 0433-1028, which is the first detection of a nearby luminous active galactic nucleus (AGN; redshift 0.0355) with the Field-Imaging Far-Infrared Line Spectrometer (FIFI-LS) on board the airborne Stratospheric Observatory For Infrared Astronomy (SOFIA). We compare the spatially resolved star formation tracers [C ii], as provided by our SOFIA observations, and Hα from the Multi Unit Spectroscopic Explorer (MUSE) optical integral-field spectroscopy. We find that the [C ii] emission is mainly matching the extended star formation as traced by the extinction-corrected Hα line emission but some additional flux is present. While a larger sample is needed to statistically confirm our findings and investigate possible dependencies on AGN luminosity and star formation rate, our study underlines the necessity of collecting a spatially resolved optical-far-infrared data set for nearby AGNs, and shows that it is technically feasible to collect such data sets with FIFI-LS on board SOFIA. © 2018. The American Astronomical Society. All rights reserved. Based in part on observations made with the NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA). SOFIA is jointly operated by the Universities Space Research Association, Inc. (USRA), under NASA contract NAS2-97001, and the Deutsches SOFIA Institut (DSI) under DLR contract 50 OK 0901 to the University of Stuttgart. We thank the anonymous referee for a constructive report that helped to clarify the manuscript. This work was supported by the Deutsche Forschungsgemeinschaft (DFG) via SFB 956, subprojects A2, and A6. The work of S.B. and C.O. was supported by NSERC (Natural Sciences and Engineering Research Council of Canada). M.G. is supported by NASA through Einstein Postdoctoral Fellowship Award No. PF5-160137 issued by the Chandra X-ray Observatory Center, which is operated by the SAO for and on behalf of NASA under contract NAS8-03060. Support for this work was also provided by Chandra grant GO7-18121X. M.K. acknowledges support by DLR 50OR1802. M.P.T. acknowledges support from the Spanish MINECO through grants AYA2012-38491-C02-02 and AYA2015-63939-C2-1-P. Peer reviewed

  • Open Access
    Authors: 
    G. Aad; B. Abbott; J. Abdallah; A.A. Abdelalim; A. Abdesselam; O. Abdinov; B. Abi; M. Abolins; H. Abramowicz; H. Abreu; +191 more
    Publisher: Elsevier BV
    Project: NSERC

    The cross section for the production of W bosons with subsequent decay W to tau nu is measured with the ATLAS detector at the LHC. The analysis is based on a data sample that was recorded in 2010 at a proton-proton center-of-mass energy of sqrt(s) = 7 TeV and corresponds to an integrated luminosity of 34 pb^-1. The cross section is measured in a region of high detector acceptance and then extrapolated to the full phase space. The product of the total W production cross section and the W to tau nu branching ratio is measured to be 11.1 +/- 0.3 (stat) +/- 1.7 (syst) +/- 0.4 (lumi) nb.

  • Open Access English
    Authors: 
    Aad, G; Abbott, B; Abdallah, J; Abdelalim, AA; Abdesselam, A; Abdinovi, O; Abi, B; Abolins, M; Abramowicz, H; Abreu, H; +191 more
    Countries: Spain, Serbia, United Kingdom, France, Turkey, France, Italy, France, Italy, Germany ...
    Project: NSERC

    A search for the Standard Model Higgs boson in the two photon decay channel is reported, using 1.08 fb−11.08 fb[superscript −1] of proton–proton collision data at a centre-of-mass energy of 7 TeV recorded by the ATLAS detector. No significant excess is observed in the investigated mass range of 110–150 GeV. Upper limits on the cross-section times branching ratio of between 2.0 and 5.8 times the Standard Model prediction are derived for this mass range. National Science Foundation (U.S.) United States. Dept. of Energy Brookhaven National Laboratory

  • Open Access
    Authors: 
    G. Aad; B. Abbott; J. Abdallah; S. Abdel Khalek; A.A. Abdelalim; O. Abdinov; B. Abi; M. Abolins; O.S. AbouZeid; H. Abramowicz; +191 more
    Publisher: Elsevier BV
    Project: NSERC

    Measurement of the top quark pair cross section with ATLAS in pp collisions at root s=7 TeV using final states with an electron or a muon and a hadronically decaying tau lepton

  • Open Access English
    Authors: 
    V. Poireau; V. Tisserand; E. Grauges; A. Palano; M. Pappagallo; B. Stugu; D. N. Brown; L. T. Kerth; Yu. G. Kolomensky; D. J. Asgeirsson; +202 more
    Publisher: HAL CCSD
    Countries: Italy, United States, Italy, Italy, Netherlands, Italy, France
    Project: NSERC

    See paper for full list of authors - 7 pages, 5 postscript figures, submitted to Phys. Rev. Lett; Recent astrophysical and terrestrial experiments have motivated the proposal of a dark sector with GeV-scale gauge boson force carriers and new Higgs bosons. We present a search for a dark Higgs boson using 516 fb-1 of data collected with the BABAR detector. We do not observe a significant signal and we set 90% confidence level upper limits on the product of the Standard Model-dark sector mixing angle and the dark sector coupling constant.

  • Open Access
    Authors: 
    K. Abe; J. Amey; M. Antonova; Akitaka Ariga; Y. Ashida; D. Autiero; S. Ban; M. Barbi; Gareth J. Barker; G.D. Barr; +195 more
    Publisher: American Physical Society (APS)
    Project: NSERC , EC | JENNIFER (644294)

    We report measurements by the T2K experiment of the parameters $\theta_{23}$ and $\Delta m^{2}_{32}$ governing the disappearance of muon neutrinos and antineutrinos in the three flavor neutrino oscillation model. Utilizing the ability of the experiment to run with either a mainly neutrino or a mainly antineutrino beam, the parameters are measured separately for neutrinos and antineutrinos. Using $7.482 \times 10^{20}$ POT in neutrino running mode and $7.471 \times 10^{20}$ POT in antineutrino mode, T2K obtained, $\sin^{2}(\theta_{23})=0.51^{+0.08}_{-0.07}$ and $\Delta m^{2}_{32} = 2.53^{+0.15}_{-0.13} \times 10^{-3}$eV$^{2}$/c$^{4}$ for neutrinos, and $\sin^{2}({\overline{\theta}}_{23})=0.42^{+0.25}_{-0.07}$ and ${\Delta\overline{m}^2}_{32} = 2.55^{+0.33}_{-0.27} \times 10^{-3}$eV$^{2}$/c$^{4}$ for antineutrinos (assuming normal mass ordering). No significant differences between the values of the parameters describing the disappearance of muon neutrinos and antineutrinos were observed.

  • Open Access
    Authors: 
    A. A. Abdelalim; Jahred Adelman; J. Albert; Theodoros Alexopoulos; G. Anders; M. L. Andrieux; Francis Anghinolfi; Alberto Annovi; Giacomo Artoni; A. Astbury; +188 more
    Publisher: Elsevier BV
    Project: NSERC

    This Letter reports a measurement of the W W production cross section in root s = 7 TeV pp collisions using data corresponding to an integrated luminosity of 1.02 fb(-1) collected with the ATLAS de ...