A search for the Standard Model Higgs boson in the two photon decay channel is reported, using 1.... more A search for the Standard Model Higgs boson in the two photon decay channel is reported, using 1.08 fb −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. 1 ATLAS uses a right-handed coordinate system with its origin at the nominal interaction point (IP) in the centre of the detector and the z-axis along the beam pipe. The x-axis points from the IP to the centre of the LHC ring, and the y axis points upward. Cylindrical coordinates (r, φ) are used in the transverse plane, φ being the azimuthal angle around the beam pipe. The pseudorapidity is defined in terms of the polar angle θ as η = − ln tan(θ/2).
A search for the direct production of charginos and neutralinos in final states with three electr... more A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb −1 of √ s = 7 TeV proton-proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results.
This letter reports a measurement of the muon charge asymmetry from W bosons produced in proton-p... more This letter reports a measurement of the muon charge asymmetry from W bosons produced in proton-proton collisions at a centre-of-mass energy of 7 TeV with the ATLAS experiment at the LHC. The asymmetry is measured in the W → µν decay mode as a function of the muon pseudorapidity using a data sample corresponding to a total integrated luminosity of 31 pb −1 . The results are compared to predictions based on next-to-leading order calculations with various parton distribution functions. This measurement provides information on the u and d quark momentum fractions in the proton.
A search for diphoton events with large missing transverse momentum has been performed using prot... more A search for diphoton events with large missing transverse momentum has been performed using proton-proton collision data at √ s = 7 TeV recorded with the ATLAS detector, corresponding to an integrated luminosity of 4.8 fb −1 . No excess of events was observed above the Standard Model prediction and model-dependent 95 % confidence level exclusion limits are set. In the context of a generalised model of gauge-mediated supersymmetry breaking with a bino-like lightest neutralino of mass above 50 GeV, gluinos (squarks) below 1.07 TeV (0.87 TeV) are excluded, while a breaking scale Λ below 196 TeV is excluded for a minimal model of gauge-mediated supersymmetry breaking. For a specific model with one universal extra dimension, compactification scales 1/R < 1.40 TeV are excluded. These limits provide the most stringent tests of these models to date.
A search for top quark pair resonances in final states containing at least one electron or muon h... more A search for top quark pair resonances in final states containing at least one electron or muon has been performed with the ATLAS experiment at the CERN Large Hadron Collider. The search uses a data sample corresponding to an integrated luminosity of 2.05 fb −1 , which was recorded in 2011 at a proton-proton centre-of-mass energy of 7 TeV. No evidence for a resonance is found and limits are set on the production cross-section times branching ratio to tt for narrow and wide resonances. For narrow Z bosons, the observed 95% Bayesian credibility level limits range from 9.3 pb to 0.95 pb for masses in the range of m Z = 500 GeV to m Z = 1300 GeV. The corresponding excluded mass region for a leptophobic topcolour Z boson (Kaluza-Klein gluon excitation in the Randall-Sundrum model) is m Z < 880 GeV (m gKK < 1130 GeV).
Hasta fines del siglo XIX se había avanzado en la etiología de muchas enfermedades infecciosas, s... more Hasta fines del siglo XIX se había avanzado en la etiología de muchas enfermedades infecciosas, sin embargo, quedaban una gran cantidad de enfermedades en el hombre, animales y plantas sin identificar el agente causal. A lo largo del siglo XX se descubrieron a los virus como causantes de enfermedades infecciosas para las cuales no se había encontrado una bacteria, hongo o protozoario como agente responsable. Fue el desarrollo de nuevas técnicas como los cultivos celulares, el mejoramiento en microscopía y el advenimiento a fines del siglo XX de técnicas de Biología Molecular, que han permitido no sólo aislar e identificar agentes virales, sino además un avance extraordinario en el conocimiento a nivel molecular en detalle de la biología de los mismos.
A search for the Standard Model Higgs boson in the two photon decay channel is reported, using 1.... more A search for the Standard Model Higgs boson in the two photon decay channel is reported, using 1.08 fb −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. 1 ATLAS uses a right-handed coordinate system with its origin at the nominal interaction point (IP) in the centre of the detector and the z-axis along the beam pipe. The x-axis points from the IP to the centre of the LHC ring, and the y axis points upward. Cylindrical coordinates (r, φ) are used in the transverse plane, φ being the azimuthal angle around the beam pipe. The pseudorapidity is defined in terms of the polar angle θ as η = − ln tan(θ/2).
A search for the direct production of charginos and neutralinos in final states with three electr... more A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb −1 of √ s = 7 TeV proton-proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results.
This letter reports a measurement of the muon charge asymmetry from W bosons produced in proton-p... more This letter reports a measurement of the muon charge asymmetry from W bosons produced in proton-proton collisions at a centre-of-mass energy of 7 TeV with the ATLAS experiment at the LHC. The asymmetry is measured in the W → µν decay mode as a function of the muon pseudorapidity using a data sample corresponding to a total integrated luminosity of 31 pb −1 . The results are compared to predictions based on next-to-leading order calculations with various parton distribution functions. This measurement provides information on the u and d quark momentum fractions in the proton.
A search for diphoton events with large missing transverse momentum has been performed using prot... more A search for diphoton events with large missing transverse momentum has been performed using proton-proton collision data at √ s = 7 TeV recorded with the ATLAS detector, corresponding to an integrated luminosity of 4.8 fb −1 . No excess of events was observed above the Standard Model prediction and model-dependent 95 % confidence level exclusion limits are set. In the context of a generalised model of gauge-mediated supersymmetry breaking with a bino-like lightest neutralino of mass above 50 GeV, gluinos (squarks) below 1.07 TeV (0.87 TeV) are excluded, while a breaking scale Λ below 196 TeV is excluded for a minimal model of gauge-mediated supersymmetry breaking. For a specific model with one universal extra dimension, compactification scales 1/R < 1.40 TeV are excluded. These limits provide the most stringent tests of these models to date.
A search for top quark pair resonances in final states containing at least one electron or muon h... more A search for top quark pair resonances in final states containing at least one electron or muon has been performed with the ATLAS experiment at the CERN Large Hadron Collider. The search uses a data sample corresponding to an integrated luminosity of 2.05 fb −1 , which was recorded in 2011 at a proton-proton centre-of-mass energy of 7 TeV. No evidence for a resonance is found and limits are set on the production cross-section times branching ratio to tt for narrow and wide resonances. For narrow Z bosons, the observed 95% Bayesian credibility level limits range from 9.3 pb to 0.95 pb for masses in the range of m Z = 500 GeV to m Z = 1300 GeV. The corresponding excluded mass region for a leptophobic topcolour Z boson (Kaluza-Klein gluon excitation in the Randall-Sundrum model) is m Z < 880 GeV (m gKK < 1130 GeV).
Hasta fines del siglo XIX se había avanzado en la etiología de muchas enfermedades infecciosas, s... more Hasta fines del siglo XIX se había avanzado en la etiología de muchas enfermedades infecciosas, sin embargo, quedaban una gran cantidad de enfermedades en el hombre, animales y plantas sin identificar el agente causal. A lo largo del siglo XX se descubrieron a los virus como causantes de enfermedades infecciosas para las cuales no se había encontrado una bacteria, hongo o protozoario como agente responsable. Fue el desarrollo de nuevas técnicas como los cultivos celulares, el mejoramiento en microscopía y el advenimiento a fines del siglo XX de técnicas de Biología Molecular, que han permitido no sólo aislar e identificar agentes virales, sino además un avance extraordinario en el conocimiento a nivel molecular en detalle de la biología de los mismos.
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Papers by Samuel Doria