1,146 research outputs found

    Cultivo y crecimiento de dos especies de diatomeas bentónicas aisladas del Salar del Huasco (Norte de Chile, 20° S) a diferentes condiciones de temperatura, luz y nutrientes

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    Benthic diatoms are cultured usually under laboratory conditions to be used as a food source for other organisms, ofaquaculture interest or for biotechnological applications. Laboratory experiments demonstrate the incidence of the physicaland chemical variables on abundance and growth rates of diatoms. While macronutrients are usually selected and dosed intocommon culture mediums to meet the general requirements of a wide range of diatoms, the availability and optimizationof micronutrients are more susceptible to each organism’s particular physiological conditions. The aim of this study was tocharacterize the growth of two species of benthic diatoms isolated from the Salar de Huasco in batch cultures at differentconditions of temperature (10, 15 and 20 °C), light intensity (40, 80 and 120 ?mol m-2 s-1) and concentrations of silica (1.06x 10-4 M Na2SiO3 x 9H2O and 2.12 x 10-4 M Na2SiO3 x 9H2O) and selenium (10-8 M H2SeO3) in f/2 medium, on a lightdarkcycle of 18:6 h. Both Nitzschia epithemioides Grunow in Cleve & Grunow (1880) as Nitzschia sp. showed highermaximum cell densities (692800 ± 107704 and 649600 ± 68942 cells ml-1, respectively) and exponential growth rates(1.80±0.56 and 0.97±0.32 div. d-1, respectively) at the highest temperature (20°C). The light intensity to which the cultureswere exposed had no effect on cell density and exponential growth rate in both taxa. Regarding to nutrients, an increasein silicates concentrations on the culture medium could promote the growth of N. epithemioides and Nitzschia sp. since atendency was observed to higher cell densities (1.08 x 106 ± 84,639 and 1.32 x 106 ± 109,038 cells ml-1, respectively) andexponential growth rates (1.98 ± 0.44 and 0.95 ± 0.18 div. d-1, respectively) with respect at the normal f/2 medium and f/2medium plus selenium. Simultaneous addition of silicate and selenium to the culture medium increased the maximum celldensity of the two strains under study, but this increase was significant (p = 0.05) only for N. epithemioides and amongthe normal f/2 medium (719200 ± 116895 cells ml-1) and the f/2 medium with double the amount of silicate and selenium(1498800 ± 209599 cells ml-1). However, the exponential growth rates were not significantly different when comparedto those of the control (without the addition of silicate and selenium). In conclusion both N. epithemioides and Nitzschiasp shown an increased cell density and exponential growth rate at 20 °C. The different light intensities not significantlyinfluenced the growth of both taxa. An increase in the concentration of silicates or simultaneous increase in silicatesand selenium in the culture medium can be considered as possible strategy to increase cell density of benthic diatom N.epithemioides in batch cultures.de alimento de otros organismos de interés acuícola o para aplicaciones biotecnológicas. Experimentos de laboratoriodemuestran la incidencia de las variables físicas y químicas sobre la abundancia y tasas de crecimiento de las diatomeas.Mientras los macronutrientes están generalmente seleccionados y dosificados en los medios de cultivo más comunespara satisfacer los requerimientos generales de un amplio rango de diatomeas, la disponibilidad y optimización demicronutrientes son más susceptibles a las condiciones fisiológicas particulares de cada organismo. El objetivo de esteestudio fue caracterizar el crecimiento de dos especies de diatomeas bentónicas aisladas del Salar de Huasco en cultivostipo batch, a diferentes condiciones de temperatura (10, 15 y 20 °C), intensidad de la luz (40, 80 y 120 ?mol m-2 s-1), y concentraciones de sílice (1.06 x 10-4 M Na2SiO3 x 9H2O y 2.12 x 10-4 M Na2SiO3 x 9H2O) y selenio (10-8 M H2SeO3)en medio f/2, a un ciclo 18:6 h luz-oscuridad. Tanto Nitzschia epithemioides Grunow in Cleve & Grunow (1880) comoNitzschia sp, exhibieron las mayores densidades celulares máximas (692800 ± 107704 y 649600 ± 68942 células mL-1,respectivamente) y tasas de crecimiento exponencial (1,80 ± 0,56 y 0,97 ± 0,32 div. d-1, respectivamente) a la temperaturamás elevada (20 °C). La intensidad de luz a la cual los cultivos fueron expuestos no afectó la densidad celular y tasa decrecimiento exponencial en ambos taxa. En cuanto a los nutrientes, un incremento en la concentración de silicatos en elmedio de cultivo, podría favorecer el crecimiento de N. epithemioides y Nitzschia sp. ya que se observó una tendenciaal aumento en la densidad celular (1,08 x 106 ± 84.639 y 1,32 x 106 ± 109.038 células mL-1, respectivamente) y tasa decrecimiento exponencial (1,98 ± 0,44 y 0,95 ± 0,18 div. d-1, respectivamente) con respecto a los medios f/2 normal y f/2más selenio. La adición simultanea de silicato y selenio al medio de cultivo aumentó las densidades celulares máximas delas dos cepas bajo estudio, pero este aumento fue significativo (p = 0,05) sólo para N. epithemioides y entre los medios decultivo f/2 normal (719200 ± 116895 células mL?1) y medio f/2 con el doble de silicato y selenio (1498800 ± 209599 célulasmL-1). Sin embargo, las tasas de crecimiento exponencial no tuvieron diferencias significativas con el control (sin adiciónde silicato y selenio). En conclusión tanto N. epithemioides y Nitzschia sp. muestran un aumento en la densidad celular yla tasa de crecimiento exponencial a 20 °C. Las diferentes intensidades de luz evaluadas no influyeron significativamenteen el crecimiento de ambos taxa. Un aumento en la concentración de silicatos o aumento simultáneo de silicatos y selenioen el medio de cultivo puede ser considerado como posible estrategia para incrementar la densidad celular de la diatomeabentónica N. epithemioides en cultivos discontinuos

    Resistance to autosomal dominant Alzheimer's disease in an APOE3 Christchurch homozygote: a case report.

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    We identified a PSEN1 (presenilin 1) mutation carrier from the world's largest autosomal dominant Alzheimer's disease kindred, who did not develop mild cognitive impairment until her seventies, three decades after the expected age of clinical onset. The individual had two copies of the APOE3 Christchurch (R136S) mutation, unusually high brain amyloid levels and limited tau and neurodegenerative measurements. Our findings have implications for the role of APOE in the pathogenesis, treatment and prevention of Alzheimer's disease

    Measurement of four-jet production in proton-proton collisions at √s=7  TeV

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    This article is available under the terms of the Creative Commons Attribution 3.0 License.-- et al.Measurements of the differential cross sections for the production of exactly four jets in proton-proton collisions are presented as a function of the transverse momentum pT and pseudorapidity η, together with the correlations in azimuthal angle and the pT balance among the jets. The data sample was collected in 2010 at a center-of-mass energy of 7 TeV with the CMS detector at the LHC, with an integrated luminosity of 36pb-1. The cross section for exactly four jets, with two hard jets of pT>50GeV each, together with two jets of pT>20GeV each, within |η|<4.7 is measured to be σ= 330±5(stat.)±45(syst.)nb. It is found that fixed-order matrix element calculations including parton showers describe the measured differential cross sections in some regions of phase space only, and that adding contributions from double parton scattering brings the Monte Carlo predictions closer to the data.We acknowledge support from BMWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MEYS (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLPFAI (Mexico); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine Uzbekistan); MON, RosAtom, RAS and RFBR (Russia); MSTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); ThEP, IPST and NECTEC (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA). Individuals have received support from the Marie-Curie programme and the European Research Council and EPLANET(EuropeanUnion); the Leventis Foundation; the A.P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation à la Recherche dans l’Industrie et dansl’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschapen Technologie (IWT-Belgium); the Ministry of Education, Youth and Sports(MEYS) of Czech Republic; the Council of Science and Industrial Research, India; the Compagnia di San Paolo(Torino); the HOMINGPLUS programme of Foundation for PolishScience, cofinanced by EU,Re-gional Development Fund; and the Thalis and Aristeia programmes cofinanced by EU-ESFand the Greek NSRF.Peer reviewe

    Observation of long-range, near-side angular correlations in pPb collisions at the LHC

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    This article is published Open Access at sciencedirect.com. It is distributed under the terms of the Creative Commons Attribution License 3.0.-- et al.Results on two-particle angular correlations for charged particles emitted in pPb collisions at a nucleon–nucleon center-of-mass energy of 5.02 TeV are presented. The analysis uses two million collisions collected with the CMS detector at the LHC. The correlations are studied over a broad range of pseudorapidity, η , and full azimuth, ϕ , as a function of charged particle multiplicity and particle transverse momentum, pTpT. In high-multiplicity events, a long-range (2<|Δη|<42<|Δη|<4), near-side (Δϕ≈0Δϕ≈0) structure emerges in the two-particle Δη –Δϕ correlation functions. This is the first observation of such correlations in proton–nucleus collisions, resembling the ridge-like correlations seen in high-multiplicity pp collisions at s=7 TeV and in AA collisions over a broad range of center-of-mass energies. The correlation strength exhibits a pronounced maximum in the range of pT=1–1.5 GeV/cpT=1–1.5 GeV/c and an approximately linear increase with charged particle multiplicity for high-multiplicity events. These observations are qualitatively similar to those in pp collisions when selecting the same observed particle multiplicity, while the overall strength of the correlations is significantly larger in pPb collisions.Acknowledge support from BMWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MEYS (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLPFAI (Mexico); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine Uzbekistan); MON, RosAtom, RAS and RFBR (Russia); MSTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); ThEP, IPST and NECTEC (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA).Peer Reviewe

    Measurement of the Υ(1S), Υ(2S), and Υ(3S) polarizations in pp collisions at √s=7 TeV

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    The polarizations of the υ(1S), υ(2S), and υ(3S) mesons are measured in proton-proton collisions at √s=7 TeV, using a data sample of υ(nS)→μ+μ- decays collected by the CMS experiment, corresponding to an integrated luminosity of 4.9 fb-1. The dimuon decay angular distributions are analyzed in three different polarization frames. The polarization parameters λ™, λφ, and λ, as well as the frame-invariant quantity λ, are presented as a function of the υ(nS) transverse momentum between 10 and 50 GeV, in the rapidity ranges |y|<0.6 and 0.6<|y|<1.2. No evidence of large transverse or longitudinal polarizations is seen in the explored kinematic region. © 2013 CERN.We acknowledge support from: BMWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, and Uzbekistan); MON, RosAtom, RAS, and RFBR (Russia); MSTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); and DOE and NSF (USA).Peer Reviewe

    Search for long-lived particles in events with photons and missing energy in proton-proton collisions at √s=7 TeV

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    This article is published Open Access at sciencedirect.com. It is distributed under the terms of the Creative Commons Attribution License 3.0.-- et al.Results are presented from a search for long-lived neutralinos decaying into a photon and an invisible particle, a signature associated with gauge-mediated supersymmetry breaking in supersymmetric models. The analysis is based on a 4.9 fb−1 sample of proton–proton collisions at √s = 7 TeV, collected with the CMS detector at the LHC. The missing transverse energy and the time of arrival of the photon at the electromagnetic calorimeter are used to search for an excess of events over the expected background. No significant excess is observed, and lower limits at the 95% confidence level are obtained on the mass of the lightest neutralino, m > 220 GeV (for cτ 6000 mm (for m < 150 GeV).We acknowledge support from BMWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MEYS (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLPFAI (Mexico); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine Uzbekistan); MON, RosAtom, RAS and RFBR (Russia); MSTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); ThEP, IPST and NECTEC (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA).Peer Reviewe

    Search for narrow resonances using the dijet mass spectrum in pp collisions at √s=8 TeV

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    Results are presented of a search for the production of new particles decaying to pairs of partons (quarks, antiquarks, or gluons), in the dijet mass spectrum in proton-proton collisions at √s=8 TeV. The data sample corresponds to an integrated luminosity of 4.0 fb-1, collected with the CMS detector at the LHC in 2012. No significant evidence for narrow resonance production is observed. Upper limits are set at the 95% confidence level on the production cross section of hypothetical new particles decaying to quark-quark, quark-gluon, or gluon-gluon final states. These limits are then translated into lower limits on the masses of new resonances in specific scenarios of physics beyond the standard model. The limits reach up to 4.8 TeV, depending on the model, and extend previous exclusions from similar searches performed at lower collision energies. For the first time mass limits are set for the Randall-Sundrum graviton model in the dijet channel.We acknowledge support from BMWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MEYS (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLPFAI (Mexico); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine Uzbekistan); MON, RosAtom, RAS and RFBR (Russia); MSTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); ThEP, IPST and NECTEC (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA).Peer Reviewe

    Search for pair production of excited top quarks in the lepton + jets final state

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    Open Access: This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0).-- et al.A search is performed for pair-produced spin-3/2 excited top quarks (t*t̄*), each decaying to a top quark and a gluon. The search uses data collected with the CMS detector from pp collisions at a center-of-mass energy of √s = 8 TeV, selecting events that have a single isolated muon or electron, an imbalance in transverse momentum, and at least six jets, of which one must be compatible with originating from the fragmentation of a b quark. The data, corresponding to an integrated luminosity of 19.5 fb-1, show no significant excess over standard model predictions, and provide a lower limit of 803 GeV at 95% confidence on the mass of the spin-3/2 t* quark in an extension of the Randall-Sundrum model, assuming a 100% branching fraction of its decay into a top quark and a gluon. This is the first search for a spin-3/2 excited top quark performed at the LHC.We acknowledge the enduring support for the construction and operation of the LHC and the CMS detector provided by the following funding agencies: the Austrian Federal Ministry of Science and Research; the Belgian Fonds de la Recherche Scientifique, and Fonds voor Wetenschappelijk Onderzoek; the Brazilian Funding Agencies (CNPq, CAPES, FAPERJ, and FAPESP); the Bulgarian Ministry of Education, Youth and Science; CERN; the Chinese Academy of Sciences, Ministry of Science and Technology, and National Natural Science Foundation of China; the Colombian Funding Agency (COLCIENCIAS); the Croatian Ministry of Science, Education and Sport; the Research Promotion Foundation, Cyprus; the Ministry of Education and Research, Recurrent financing contract SF0690030s09 and European Regional Development Fund, Estonia; the Academy of Finland, Finnish Ministry of Education and Culture, and Helsinki Institute of Physics; the Institut National de Physique Nucle´aire et de Physique des Particules/CNRS, and Commissariat à l’Énergie Atomique et aux E'nergies Alternatives/CEA, France; the Bundesministerium für Bildung und Forschung, Deutsche Forschungsgemeinschaft, and Helmholtz-Gemeinschaft Deutscher Forschungszentren, Germany; the General Secretariat for Research and Technology, Greece; the National Scientific Research Foundation, and National Office for Research and Technology, Hungary; the Department of Atomic Energy and the Department of Science and Technology, India; the Institute for Studies in Theoretical Physics and Mathematics, Iran; the Science Foundation, Ireland; the Istituto Nazionale di Fisica Nucleare, Italy; the Korean Ministry of Education, Science and Technology and the World Class University program of NRF, Republic of Korea; the Lithuanian Academy of Sciences; the Mexican Funding Agencies (CINVESTAV, CONACYT, SEP, and UASLP-FAI); the Ministry of Science and Innovation, New Zealand; the Pakistan Atomic Energy Commission; the Ministry of Science and Higher Education and the National Science Centre, Poland; the Fundaçao para a Ciência e a Tecnologia, Portugal; JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); the Ministry of Education and Science of the Russian Federation, the Federal Agency of Atomic Energy of the Russian Federation, Russian Academy of Sciences, and the Russian Foundation for Basic Research; the Ministry of Science and Technological Development of Serbia; the Secretaría de Estado de Investigación, Desarrollo e Innovación and Programa Consolider-Ingenio 2010, Spain; the Swiss Funding Agencies (ETH Board, ETH Zurich, PSI, SNF, UniZH, Canton Zurich, and SER); the National Science Council, Taipei; the Thailand Center of Excellence in Physics, the Institute for the Promotion of Teaching Science and Technology of Thailand and the National Science and Technology Development Agency of Thailand; the Scientific and Technical Research Council of Turkey, and Turkish Atomic Energy Authority; the Science and Technology Facilities Council, U.K.; the U.S. Department of Energy, and the U.S. National Science Foundation. Individuals have received support from the Marie-Curie program and the European Research Council (European Union); the Leventis Foundation; the A. P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of Czech Republic; the Council of Science and Industrial Research, India; the Compagnia di San Paolo (Torino); and the HOMING PLUS program of Foundation for Polish Science, cofinanced from European Union, Regional Development Fund; and the Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF.Article funded by SCOAP3.Peer Reviewe

    Search in leptonic channels for heavy resonances decaying to long-lived neutral particles

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    Open Access: This article is distributed under the terms of the Creative Commons Attribution License.-- et al.A search is performed for heavy resonances decaying to two long-lived massive neutral particles, each decaying to leptons. The experimental signature is a distinctive topology consisting of a pair of oppositely charged leptons originating at a separated secondary vertex. Events were collected by the CMS detector at the LHC during pp collisions at s √ =7 TeV, and selected from data samples corresponding to 4.1 (5.1) fb−1 of integrated luminosity in the electron (muon) channel. No significant excess is observed above standard model expectations, and an upper limit is set with 95% confidence level on the production cross section times the branching fraction to leptons, as a function of the long-lived massive neutral particle lifetime.We acknowledge support from BMWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MEYS (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLPFAI (Mexico); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine Uzbekistan); MON, RosAtom, RAS and RFBR (Russia); MSTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); ThEP, IPST and NECTEC (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA).Peer Reviewe

    Search for flavor-changing neutral currents in top-quark decays t →zq in pp collisions at √s = 8TeV

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    This article is available under the terms of the Creative Commons Attribution 3.0 License.-- et al.A search for flavor-changing neutral currents in top-quark decays t→Zq is performed in events produced from the decay chain tt̄→Zq+Wb, where both vector bosons decay leptonically, producing a final state with three leptons (electrons or muons). A data set collected with the CMS detector at the LHC is used, corresponding to an integrated luminosity of 19.7fb-1 of proton-proton collisions at a center-of-mass energy of 8 TeV. No excess is seen in the observed number of events relative to the standard model prediction; thus, no evidence for flavor-changing neutral currents in top-quark decays is found. A combination with a previous search at 7 TeV excludes a t→Zq branching fraction greater than 0.05% at the 95% confidence level. © 2014 CERN, for the CMS Collaboration.We acknowledge support from BMWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MEYS (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLPFAI (Mexico); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine Uzbekistan); MON, RosAtom, RAS and RFBR (Russia); MSTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); ThEP, IPST and NECTEC (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA).Peer Reviewe
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