Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV

The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of √s = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT≥20 GeV and pseudorapidities {pipe}η{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}η{pipe}<0. 8) for jets with 60≤pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2≤{pipe}η{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. © 2013 CERN for the benefit of the ATLAS collaboration

Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal

Photobiocatalytic chemistry of oxidoreductases using water as the electron donor

[EN] To date, water has been poorly studied as the sacrificial electron donor for biocatalytic redox reactions using isolated enzymes. Here we demonstrate that water can also be turned into a sacrificial electron donor to promote biocatalytic redox reactions. The thermodynamic driving force required for water oxidation is obtained from UV and visible light by means of simple titanium dioxide-based photocatalysts. The electrons liberated in this process are delivered to an oxidoreductase by simple flavin redox mediators. Overall, the feasibility of photobiocatalytic, water-driven bioredox reactions is demonstrated.Financial support from the Spanish Science and Innovation Ministry (Consolider Ingenio 2010-MULTICAT CSD 2009-00050, Subprograma de apoyo a Centros y Universidades de Excelencia Severo Ochoa SEV 2012 0267). M. M. acknowledges the Spanish Science and Innovation Ministry for a 'Juan de la Cierva' postdoctoral contract. S. G. acknowledges the European Union Marie Curie Programme (ITN 'Biotrains', Grant Agreement No. 238531).Mifsud Grau, M.; Gargiulo, S.; Iborra Chornet, S.; Arends, IWCE.; Hollmann, F.; Corma Canós, A. (2014). Photobiocatalytic chemistry of oxidoreductases using water as the electron donor. Nature Communications. 5:1-6. https://doi.org/10.1038/ncomms4145S165Bornscheuer, U. T. et al. Engineering the third wave of biocatalysis. Nature 485, 185–194 (2012).Breuer, M. et al. Industrial methods for the production of optically active intermediates. Angew. Chem. Int. Ed. 43, 788–824 (2004).Pollard, D. J. & Woodley, J. M. Biocatalysis for pharmaceutical intermediates: the future is now. Trends Biotechnol. 25, 66–73 (2007).Ran, N., Zhao, L., Chen, Z. & Tao, J. Recent applications of biocatalysis in developing green chemistry for chemical synthesis at the industrial scale. Green. Chem. 10, 361–372 (2008).Schmid, A. et al. Industrial biocatalysis today and tomorrow. Nature 409, 258–268 (2001).Schmid, A., Hollmann, F., Park, J. B. & Bühler, B. The use of enzymes in the chemical industry in Europe. Curr. Opin. Biotechnol. 13, 359–366 (2002).Schoemaker, H. E., Mink, D. & Wubbolts, M. G. Dispelling the myths-biocatalysis in industrial synthesis. Science 299, 1694–1697 (2003).Turner, N. J. & O’Reilly, E. Biocatalytic retrosynthesis. Nat. Chem. Biol. 9, 285–288 (2013).Drauz K., Gröger H., May O. (eds)Enzyme Catalysis in Organic Synthesis Wiley-VCH: Weinheim, (2012).Weckbecker, A., Gröger, H. & Hummel, W. Regeneration of nicotinamide coenzymes: principles and applications for the synthesis of chiral compounds. inBiosystems Engineering I: Creating Superior Biocatalysts pp195–242Springer: Berlin, (2010).Van der Donk, W. A. & Zhao, H. Recent developments in pyridine nucleotide regeneration. Curr. Opin. Biotechnol. 14, 421–426 (2003).Wu, H. et al. Methods for the regeneration of nicotinamide coenzymes. Green. Chem. 15, 1773–1789 (2013).Rodriguez, C., Lavandera, I. & Gotor, V. Recent advances in cofactor regeneration systems applied to biocatalyzed oxidative processes. Curr. Org. Chem. 16, 2525–2541 (2012).Reipa, V., Mayhew, M. P. & Vilker, V. L. A direct electrode-driven P450 cycle for biocatalysis. Proc. Natl Acad. Sci. USA 94, 13554–13558 (1997).Bernard, J., van Heerden, E., Arends, I. W. C. E., Opperman, D. J. & Hollmann, F. Chemoenzymatic reduction of conjugated C=C double bonds. Chem. Cat. Chem. 4, 196–199 (2012).Hollmann, F., Arends, I. W. C. E. & Bühler, K. Biocatalytic redox reactions for organic synthesis: nonconventional regeneration methods. Chem. Cat. Chem. 2, 762–782 (2010).Hollmann, F., Hofstetter, K., Habicher, T., Hauer, B. & Schmid, A. Direct electrochemical regeneration of monooxygenase subunits for biocatalytic asymmetric epoxidation. J. Am. Chem. Soc. 127, 6540–6541 (2005).Hollmann, F., Lin, P.-C., Witholt, B. & Schmid, A. Stereospecific biocatalytic epoxidation: the first example of direct regeneration of a fad-dependent monooxygenase for catalysis. J. Am. Chem. Soc. 125, 8209–8217 (2003).Hollmann, F. & Schmid, A. Towards [Cp*Rh(bpy)(H2O)]2+-promoted P450 catalysis: direct regeneration of CytC. J. Inorg. Biochem. 103, 313–315 (2009).Hollmann, F., Taglieber, A., Schulz, F. & Reetz, M. T. A light-driven stereoselective biocatalytic oxidation. Angew. Chem. Int. Ed. 46, 2903–2906 (2007).Mifsud Grau, M. et al. Photoenzymatic reduction of C=C double bonds. Adv. Synth. Catal. 351, 3279–3286 (2009).Ruinatscha, R., Dusny, C., Buehler, K. & Schmid, A. Productive asymmetric styrene epoxidation based on a next generation electroenzymatic methodology. Adv. Synth. Catal. 351, 2505–2515 (2009).Schwaneberg, U., Appel, D., Schmitt, J. & Schmid, R. D. P450 in biotechnology: zinc driven ω-hydroxylation of p-nitrophenoxydodecanoic acid using P450 BM-3 F87A as a catalyst. J. 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Integrated photosystem II-based photo-bioelectrochemical cells. Nat. Commun. 3, 742 (2012).Duan, L. et al. A molecular ruthenium catalyst with water-oxidation activity comparable to that of photosystem II. Nat. Chem. 4, 418–423 (2012).Dau, H., Zaharieva, I. & Haumann, M. Recent developments in research on water oxidation by photosystem II. Curr. Opin. Chem. Biol. 16, 3–10 (2012).Qu, Y. & Duan, X. Progress, challenge and perspective of heterogeneous photocatalysts. Chem. Soc. Rev. 42, 2568–2580 (2013).Takanabe, K. & Domen, K. Preparation of inorganic photocatalytic materials for overall water splitting. Chem. Cat. Chem. 4, 1485–1497 (2012).Wee, T.-L. et al. Photochemical synthesis of a water oxidation catalyst based on cobalt nanostructures. J. Am. Chem. Soc. 133, 16742–16745 (2011).Cargnello, M. & Fornasiero, P. Photocatalysis by nanostructured TiO2 based semiconductors. inHandbook of Green Chemistry, Green Nanoscience (eds Selva M., Perosa A. Wiley-VCH: Weinheim, (2010).Liu, S. Q. & Chen, A. C. Coadsorption of horseradish peroxidase with thionine on TiO2: Nanotubes for biosensing. Langmuir 21, 8409–8413 (2005).Zhang, Y., He, P. L. & Hu, N. F. Horseradish peroxidase immobilized in TiO2 nanoparticle films on pyrolytic graphite electrodes: direct electrochemistry and bioelectrocatalysis. Electrochim. Acta 49, 1981–1988 (2004).Chen, D., Zhang, H., Li, X. & Li, J. H. Biofunctional titania nanotubes for visible-light-activated photoelectrochemical biosensing. Anal. Chem. 82, 2253–2261 (2010).Gomes Silva, C. U., Juárez, R., Marino, T., Molinari, R. & García, H. Influence of excitation wavelength (UV or visible light) on the photocatalytic activity of titania containing gold nanoparticles for the generation of hydrogen or oxygen from water. J. Am. Chem. Soc. 133, 595–602 (2010).Opperman, D. J., Piater, L. A. & van Heerden, E. A novel chromate reductase from Thermus scotoductus SA-01 related to old yellow enzyme. J. Bacteriol. 190, 3076–3082 (2008).Opperman, D. J. et al. Crystal structure of a thermostable old yellow enzyme from Thermus scotoductus SA-01. Biochem. Biophys. Res. Commun. 393, 426–431 (2010).Choi, S. H. et al. The influence of non-stoichiometric species of V/TiO2 catalysts on selective catalytic reduction at low temperature. J. Mol. Catal. A: Chem. 304, 166–173 (2009)

Measurement of the cross-section for b-jets produced in association with a Z boson at root s=7 TeV with the ATLAS detector ATLAS Collaboration

A measurement is presented of the inclusive cross-section for b-jet production in association with a Z boson in pp collisions at a centre-of-mass energy of root s = 7 TeV. The analysis uses the data sample collected by the ATLAS experiment in 2010, corresponding to an integrated luminosity of approximately 36 pb(-1). The event selection requires a Z boson decaying into high P-T electrons or muons, and at least one b-jet, identified by its displaced vertex, with transverse momentum p(T) > 25 GeV and rapidity vertical bar y vertical bar < 2.1. After subtraction of background processes, the yield is extracted from the vertex mass distribution of the candidate b-jets. The ratio of this cross-section to the inclusive Z cross-section (the average number of b-jets per Z event) is also measured. Both results are found to be in good agreement with perturbative QCD predictions at next-to-leading order

Search for long-lived heavy neutral leptons with lepton flavour conserving or violating decays to a jet and a charged lepton

A preprint version of the article is available at arXiv:2312.07484v3 [hep-ex], https://arxiv.org/abs/2312.07484 . Comments: Replaced with the published version. Added the journal reference and the DOI. All the figures and tables can be found at https://cms-results.web.cern.ch/cms-results/public-results/publications/EXO-21-013 (CMS Public Pages)A search for long-lived heavy neutral leptons (HNLs) is presented, which considers the hadronic final state and coupling scenarios involving all three lepton generations in the 2-20 GeV HNL mass range for the first time. Events comprising two leptons (electrons or muons) and jets are analyzed in a data sample of proton-proton collisions, recorded with the CMS experiment at the CERN LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb−1. A novel jet tagger, based on a deep neural network, has been developed to identify jets from an HNL decay using various features of the jet and its constituent particles. The network output can be used as a powerful discriminating tool to probe a broad range of HNL lifetimes and masses. Contributions from background processes are determined from data. No excess of events in data over the expected background is observed. Upper limits on the HNL production cross section are derived as functions of the HNL mass and the three coupling strengths VℓN to each lepton generation ℓ and presented as exclusion limits in the coupling-mass plane, as lower limits on the HNL lifetime, and on the HNL mass. In this search, the most stringent limit on the coupling strength is obtained for pure muon coupling scenarios; values of |VμN|2 > 5 (4) × 10−7 are excluded for Dirac (Majorana) HNLs with a mass of 10 GeV at a confidence level of 95% that correspond to proper decay lengths of 17 (10) mm.SCOAP3

The embryo as moral work object: PGD/IVF staff views and experiences

Copyright @ 2008 the authors. This article is available in accordance with the Creative Commons Deed, Attribution 2.5, see http://creativecommons.org/licenses/by-nc-nd/2.5/deed.en_CA.We report on one aspect of a study that explored the views and experiences of practitioners and scientists on social, ethical and clinical dilemmas encountered when working in the field of preimplantation genetic diagnosis (PGD) for serious genetic disorders. The study produced an ethnography based on observation, interviews and ethics discussion groups with staff from two PGD/IVF Units in the UK. We focus here on staff perceptions of work with embryos that entails disposing of ‘affected’ or ‘spare’ embryos or using them for research. A variety of views were expressed on the ‘embryo question’ in contrast to polarised media debates. We argue that the prevailing policy acceptance of destroying affected embryos, and allowing research on embryos up to 14 days leaves some staff with rarely reported, ambivalent feelings. Staff views are under-researched in this area and we focus on how they may reconcile their personal moral views with the ethical framework in their field. Staff construct embryos in a variety of ways as ‘moral work objects’. This allows them to shift attention between micro-level and overarching institutional work goals, building on Casper's concept of ‘work objects’ and focusing on negotiation of the social order in a morally contested field.The Wellcome Trust Biomedical Ethics Programme, who funded the projects‘Facilitating choice, framing choice: the experience of staff working in pre-implantation genetic diagnosis’ (no: 074935), and ‘Ethical Frameworks for Embryo Donation:the views and practices of IVF/PGD staff’ (no: 081414)