64 research outputs found

    Measurement of the dependence of transverse energy production at large pseudorapidity on the hard-scattering kinematics of proton-proton collisions at √s=2.76 TeV with ATLAS

    Get PDF
    The relationship between jet production in the central region and the underlying-event activity in a pseudorapidity-separated region is studied in 4.0 pb-1 of s=2.76 TeV pp collision data recorded with the ATLAS detector at the LHC. The underlying event is characterised through measurements of the average value of the sum of the transverse energy at large pseudorapidity downstream of one of the protons, which are reported here as a function of hard-scattering kinematic variables. The hard scattering is characterised by the average transverse momentum and pseudorapidity of the two highest transverse momentum jets in the event. The dijet kinematics are used to estimate, on an event-by-event basis, the scaled longitudinal momenta of the hard-scattered partons in the target and projectile beam-protons moving toward and away from the region measuring transverse energy, respectively. Transverse energy production at large pseudorapidity is observed to decrease with a linear dependence on the longitudinal momentum fraction in the target proton and to depend only weakly on that in the projectile proton. The results are compared to the predictions of various Monte Carlo event generators, which qualitatively reproduce the trends observed in data but generally underpredict the overall level of transverse energy at forward pseudorapidity

    Measurement of W boson angular distributions in events with high transverse momentum jets at s√= 8 TeV using the ATLAS detector

    Get PDF
    The W boson angular distribution in events with high transverse momentum jets is measured using data collected by the ATLAS experiment from proton–proton collisions at a centre-of-mass energy at the Large Hadron Collider, corresponding to an integrated luminosity of . The focus is on the contributions to processes from real W emission, which is achieved by studying events where a muon is observed close to a high transverse momentum jet. At small angular separations, these contributions are expected to be large. Various theoretical models of this process are compared to the data in terms of the absolute cross-section and the angular distributions of the muon from the leptonic W decay.Fil: Aaboud, M.. Université Mohamed Premier and LPTPM; MarruecosFil: Aad, G.. Aix-Marseille Université ; FranciaFil: Abbott, B.. Oklahoma State University; Estados UnidosFil: Abdallah, J.. Academia Sinica; ChinaFil: Abdinov, O.. Azerbaijan Academy of Sciences; AzerbaiyánFil: Alconada Verzini, María Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Alonso, Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Arduh, Francisco Anuar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Dova, Maria Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Hoya, Joaquín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Monticelli, Fernando Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Wahlberg, Hernan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Bossio Sola, Jonathan David. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Marceca, Gino. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Otero y Garzon, Gustavo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Piegaia, Ricardo Nestor. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Sacerdoti, Sabrina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Zibell. A.. Julius-Maximilians-Universität ; AlemaniaFil: Zieminska, D.. Indiana University; Estados UnidosFil: Zimine, N. I.. Joint Institute for Nuclear Research; RusiaFil: Zimmermann, C.. Universität Mainz ; AlemaniaFil: Zimmermann, S.. Albert-Ludwigs-Universität ; AlemaniaFil: Zinonos, Z.. Georg-August-Universität ; AlemaniaFil: Zinser, M.. Universität Mainz ; AlemaniaFil: Ziolkowski, M.. Universität Siegen ; AlemaniaFil: Živković, L.. University of Belgrade ; SerbiaFil: Zobernig, G.. University of Wisconsin; Estados UnidosFil: Zoccoli, A.. Università di Bologna ; ItaliaFil: Nedden, M. zur. Humboldt University; AlemaniaFil: Zurzolo, G.. Università di Napoli; ItaliaFil: Zwalinski, L.. Cern - European Organization For Nuclear Research; SuizaFil: The ATLAS Collaboration. No especifica

    Erratum: Search for Resonant and Nonresonant Higgs Boson Pair Production in the bb[over ¯]τ^{+}τ^{-} Decay Channel in pp Collisions at sqrt[s]=13  TeV with the ATLAS Detector [Phys. Rev. Lett. 121, 191801 (2018)]

    Get PDF

    Search for pair-produced resonances decaying to quark pairs in proton-proton collisions at root s=13 TeV

    Get PDF
    A general search for the pair production of resonances, each decaying to two quarks, is reported. The search is conducted separately for heavier resonances (masses above 400 GeV), where each of the four final-state quarks generates a hadronic jet resulting in a four-jet signature, and for lighter resonances (masses between 80 and 400 GeV), where the pair of quarks from each resonance is collimated and reconstructed as a single jet resulting in a two-jet signature. In addition, a b-tagged selection is applied to target resonances with a bottom quark in the final state. The analysis uses data collected with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 35.9 fb(-1), from proton-proton collisions at a center-of-mass energy of 13 TeV. The mass spectra are analyzed for the presence of new resonances, and are found to be consistent with standard model expectations. The results are interpreted in the framework of R-parity-violating supersymmetry assuming the pair production of scalar top quarks decaying via the hadronic coupling lambda ''(312) or lambda ''(323) and upper limits on the cross section as a function of the top squark mass are set. These results probe a wider range of masses than previously explored at the LHC, and extend the top squark mass limits in the (t) over tilde -> qq' scenario.Peer reviewe

    Operation and performance of the ATLAS Tile Calorimeter in Run 1

    Get PDF
    The Tile Calorimeter is the hadron calorimeter covering the central region of the ATLAS experiment at the Large Hadron Collider. Approximately 10,000 photomultipliers collect light from scintillating tiles acting as the active material sandwiched between slabs of steel absorber. This paper gives an overview of the calorimeter’s performance during the years 2008–2012 using cosmic-ray muon events and proton–proton collision data at centre-of-mass energies of 7 and 8TeV with a total integrated luminosity of nearly 30 fb−1. The signal reconstruction methods, calibration systems as well as the detector operation status are presented. The energy and time calibration methods performed excellently, resulting in good stability of the calorimeter response under varying conditions during the LHC Run 1. Finally, the Tile Calorimeter response to isolated muons and hadrons as well as to jets from proton–proton collisions is presented. The results demonstrate excellent performance in accord with specifications mentioned in the Technical Design Report

    Deep eutectic solvents and heterogeneous catalysis with metallic nanoparticles: A powerful partnership in sustainable synthesis

    No full text
    The last decade has seen a remarkable interest in Deep Eutectic Solvents (DESs), usually obtained from biorenewable, cheap and non-toxic precursors, as effective environmentally responsible reaction media for transition-metal-catalyzed organic transformations. One of the main advantages associ-ated with the use of these neoteric solvents is the ease of recyclability of both the catalytic system under study and the eutectic mixture, which paves the way for their implementation in heterogeneous catalysis. In this Current Opinion, a discus-sion is offered to highlight recent studies published, in particular since 2018, in which transition-metal-based nanoparticles have been efficiently coupled with DESs in the following synthetic protocols: i) C-C and C-X (X = N, O, S) coupling reactions; ii) oxidation/reduction processes; iii) synthesis of heterocycles/ cycloisomerizations; and iv) polymerization reactions

    Simultaneous Determination of Creatinine and Creatine in Human Serum by Double-Spike Isotope Dilution Liquid Chromatography–Tandem Mass Spectrometry (LC-MS/MS) and Gas Chromatography–Mass Spectrometry (GC-MS)

    No full text
    This work describes the first multiple spiking isotope dilution procedure for organic compounds using <sup>13</sup>C labeling. A double-spiking isotope dilution method capable of correcting and quantifying the creatine–creatinine interconversion occurring during the analytical determination of both compounds in human serum is presented. The determination of serum creatinine may be affected by the interconversion between creatine and creatinine during sample preparation or by inefficient chemical separation of those compounds by solid phase extraction (SPE). The methodology is based on the use differently labeled <sup>13</sup>C analogues (<sup>13</sup>C<sub>1</sub>-creatinine and <sup>13</sup>C<sub>2</sub>-creatine), the measurement of the isotopic distribution of creatine and creatinine by liquid chromatography–tandem mass spectrometry (LC-MS/MS) and the application of multiple linear regression. Five different lyophilized serum-based controls and two certified human serum reference materials (ERM-DA252a and ERM-DA253a) were analyzed to evaluate the accuracy and precision of the proposed double-spike LC-MS/MS method. The methodology was applied to study the creatine–creatinine interconversion during LC-MS/MS and gas chromatography–mass spectrometry (GC-MS) analyses and the separation efficiency of the SPE step required in the traditional gas chromatography–isotope dilution mass spectrometry (GC-IDMS) reference methods employed for the determination of serum creatinine. The analysis of real serum samples by GC-MS showed that creatine–creatinine separation by SPE can be a nonquantitative step that may induce creatinine overestimations up to 28% in samples containing high amounts of creatine. Also, a detectable conversion of creatine into creatinine was observed during sample preparation for LC-MS/MS. The developed double-spike LC-MS/MS improves the current state of the art for the determination of creatinine in human serum by isotope dilution mass spectrometry (IDMS), because corrections are made for all the possible errors derived from the sample preparation step

    Rhodium Complexes with a Pyridine-2-yloxy-silyl-Based N,Si-Ligand: Bonding Situation and Activity as Alkene Hydrogenation Catalysts

    No full text
    Rh(III) complexes [Rh(H)(X)(κ2-NSitBu2OPy)(L)] (X = Cl, L = PCy3, 2a; PHtBu2, 2b; X = OTf, L = PCy3, 3a; PHtBu2, 3b) (NSitBu2OPy = 4-methylpyridin-2-yloxy-ditertbutylsilyl) have been prepared and characterized by means of elemental analysis and nuclear magnetic resonance (NMR) spectroscopy. The solid-state structures of complexes 2a, 2b, and 3a have been determined by X-ray diffraction studies. Computational analyses of the bonding situation of these species evidence the electron-sharing nature of the Rh–Si bond and the significant role of the electrostatic component in the interaction between the transition metal fragment [Rh(H)(PR3)(X)]• and the [NSitBu2OPy]• ligand. In addition, a comparative study of the activity of 2a, 2b, 3a, 3b, and related iridium species as catalysts for the hydrogenation of olefins has been performed. The best catalytic results have been obtained when using the Rh(III) species 3a, with triflate and PCy3 ligands, as catalyst. Computational density functional theory studies show that the formation of the alkane is thermodynamically favored and that the rate-limiting step corresponds to the hydrogen activation, which takes place via a σ-complex-assisted metathesis mechanism

    Rhodium Complexes with a Pyridine-2-yloxy-silyl-Based N,Si-Ligand: Bonding Situation and Activity as Alkene Hydrogenation Catalysts

    No full text
    Rh(III) complexes [Rh(H)(X)(κ2-NSitBu2OPy)(L)] (X = Cl, L = PCy3, 2a; PHtBu2, 2b; X = OTf, L = PCy3, 3a; PHtBu2, 3b) (NSitBu2OPy = 4-methylpyridin-2-yloxy-ditertbutylsilyl) have been prepared and characterized by means of elemental analysis and nuclear magnetic resonance (NMR) spectroscopy. The solid-state structures of complexes 2a, 2b, and 3a have been determined by X-ray diffraction studies. Computational analyses of the bonding situation of these species evidence the electron-sharing nature of the Rh–Si bond and the significant role of the electrostatic component in the interaction between the transition metal fragment [Rh(H)(PR3)(X)]• and the [NSitBu2OPy]• ligand. In addition, a comparative study of the activity of 2a, 2b, 3a, 3b, and related iridium species as catalysts for the hydrogenation of olefins has been performed. The best catalytic results have been obtained when using the Rh(III) species 3a, with triflate and PCy3 ligands, as catalyst. Computational density functional theory studies show that the formation of the alkane is thermodynamically favored and that the rate-limiting step corresponds to the hydrogen activation, which takes place via a σ-complex-assisted metathesis mechanism

    Quantitative Evaluation of Cisplatin Uptake in Sensitive and Resistant Individual Cells by Single-Cell ICP-MS (SC-ICP-MS)

    No full text
    One of the main limitations to the Pt-therapy in cancer is the development of associated drug resistance that can be associated with a significant reduction of the intracellular platinum concentration. Thus, intracellular Pt concentration could be considered as a biomarker of cisplatin resistance. In this work, an alternative method to address intracellular Pt concentration in individual cells is explored to permit the evaluation of different cell models and alternative therapies in a relatively fast way. For this aim, total Pt analysis in single cells has been implemented using a total consumption nebulizer coupled to inductively coupled plasma mass spectrometric detection (ICP-MS). The efficiency of the proposed device has been evaluated in combination with flow cytometry and turned out to be around 25% (cells entering the ICP-MS from the cells in suspension). Quantitative uptake studies of a nontoxic Tb-containing compound by individual cells were conducted and the results compared to those obtained by bulk analysis of the same cells. Both sets of data were statistically comparable. Thus, final application of the developed methodology to the comparative uptake of Pt-species in cisplatin resistant and sensitive cell lines (A2780cis and A2780) was conducted. The results obtained revealed the potential of this analytical strategy to differentiate between different cell lines of different sensitivity to the drug which might be of high medical interest
    corecore