866 research outputs found
A Search for Randall-Sundrum Gravitons Decaying to Photon Pairs in √s = 7 TeV pp Collisions at the ATLAS experiment of the Large Hadron Collider
No full textA variety of new physics models involving extra dimensions predict photons in the final states from pp collisions at energies accessible at the Large Hadron Collider. The search for new particles in the diphoton channel, such as the Kaluza-Klein resonant mode of the graviton in the Randall-Sundrum model, carried out by the ATLAS experiment is presented. Event selection and optimization, as well as data-driven methods for estimating the background and efficiencies are discussed. Particular emphasis is given to the statistical treatment for the contrast of the null and alternative hypothesis. Making use of 36 pb-1 of pp collisions data at TeV , bounds on the production cross section times branching ratio for the Randall-Sundrum graviton as a function of diphoton mass are shown, including a comparison with the results from Tevatron
Search for resonances in lepton pairs and photon pairs with the ATLAS detector
No full textResonances decaying into a pair of particles are an obvious place to look for phenomena beyond the Standard Model. This talk summarizes recent results on searches for resonances in lepton pairs, leptons and missing transverse energy and pairs of photons. The models considered are the Z' and W', the Randall-Sundrum gravitons as well as the ADD large extra dimension scenario. The talk presents results from searches for new physics in final states containing pairs of electrons or muons using the full data sample recorded in 2011 at sqrt(s)=7 TeV centre-of-mass energy by the ATLAS experiment at the LHC. If ready it will also add a first look at the data collected in early 201
Measurement of the inelastic proton–proton cross-section at √s=7 TeV with the ATLAS Detector
No full textA first measurement of the inelastic cross-section is presented for proton-proton collisions at a center of mass energy √ =7 TeV using the ATLAS detector at the Large Hadron Collider. In a dataset corresponding to an integrated luminosity of 20 µb<sup>-1</sup>, events are selected by requiring hits on scintillation counters mounted in the forward region of the detector. An inelastic cross-section of 60.3 ± 2.1 mb is measured for ξ>5x10<sup>-6</sup>, where ξ=M<sup>2</sup><sub>X</sub>/s is calculated from the invariant mass, M<sub>X</sub>, of hadrons selected using the largest rapidity gap in the event. For diffractive events this corresponds to requiring at least one of the dissociation masses to be larger than 15.7 GeV
Measurement of the b-hadron production cross section using decays to D∗ +μ −X final states in pp collisions at √<span style="text-decoration:overline">s</span>=7 TeV with the ATLAS detector
No full textThe b-hadron production cross section is measured with the ATLAS detector in pp collisions at
√<span style="text-decoration:overline">s</span>=7 TeV, using 3.3 pb−1
of integrated luminosity, collected during the 2010 LHC run. The b-hadrons
are selected by partially reconstructing D∗+μ
−X final states. Differential cross sections are measured as
functions of the transverse momentum and pseudorapidity. The measured production cross section for a
b-hadron withpT
>9 GeV and |η|<2.5 is 32.7±0.8(stat.)+4.5
−6.8
(syst.) µb, higher than the next-to-leadingorder QCD predictions but consistent within the experimental and theoretical uncertainties
Measurement of the b-hadron production cross section using decays to D∗+μ−X final states in pp collisions at √s = 7 TeV with the ATLAS detector
No full textThe b-hadron production cross section is measured with the ATLAS detector in pp collisions at √s = 7 TeV, using 3.3 pb−1 of integrated luminosity, collected during the 2010 LHC run. The b-hadrons are selected by partially reconstructing D∗+μ−X final states. Differential cross sections are measured as functions of the transverse momentum and pseudorapidity. The measured production cross section for a b-hadron with pT > 9 GeV and |η| < 2.5 is 32.7±0.8(stat.)+4.5 −6.8(syst.) μb, higher than the next-to-leading- order QCD predictions but consistent within the experimental and theoretical uncertainties.Facultad de Ciencias Exacta
Measurement of the b-hadron production cross section using decays to D∗+μ−X final states in pp collisions at √s = 7 TeV with the ATLAS detector
No full textThe b-hadron production cross section is measured with the ATLAS detector in pp collisions at √s = 7 TeV, using 3.3 pb−1 of integrated luminosity, collected during the 2010 LHC run. The b-hadrons are selected by partially reconstructing D∗+μ−X final states. Differential cross sections are measured as functions of the transverse momentum and pseudorapidity. The measured production cross section for a b-hadron with pT > 9 GeV and |η| < 2.5 is 32.7±0.8(stat.)+4.5 −6.8(syst.) μb, higher than the next-to-leading- order QCD predictions but consistent within the experimental and theoretical uncertainties.La lista completa de autores puede verse en el archivo asociado.Instituto de Física La Plat
Search for a CP-odd Higgs boson decaying to Zh in pp collisions at root s=8 TeV with the ATLAS detector
No full textSee paper for full list of authors – 13 pages plus author list + cover pages (30 pages total), 5 figures, 2 tables, submitted to Phys. Lett. B, All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2013-06/International audienceA search for a heavy, CP-odd Higgs boson, , decaying into a boson and a 125 GeV Higgs boson, , with the ATLAS detector at the LHC is presented. The search uses proton--proton collision data at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20.3 fb. Decays of CP-even bosons to or pairs with the boson decaying to electron or muon pairs are considered, as well as decays with the boson decaying to neutrinos. No evidence for the production of an boson in these channels is found and the 95% confidence level upper limits derived for \sigma (gg\rightarrow A) \times \mbox{BR}(A \rightarrow Zh) \times \mbox{BR}(h \rightarrow f\bar{f}) are 0.098--0.013 pb for and 0.57--0.014 pb for in a range of 220--1000 GeV. The results are combined and interpreted in the context of two-Higgs doublet models
Measurement of the low-mass Drell-Yan differential cross section at √s = 7 TeV using the ATLAS detector
No full textThe differential cross section for the process Z/γ ∗ → ℓℓ (ℓ = e, μ) as a function of dilepton invariant mass is measured in pp collisions at s√ = 7 TeV at the LHC using the ATLAS detector. The measurement is performed in the e and μ channels for invariant masses between 26 GeV and 66 GeV using an integrated luminosity of 1.6 fb−1 collected in 2011 and these measurements are combined. The analysis is extended to invariant masses as low as 12 GeV in the muon channel using 35 pb−1 of data collected in 2010. The cross sections are determined within fiducial acceptance regions and corrections to extrapolate the measurements to the full kinematic range are provided. Next-to-next-to-leading-order QCD predictions provide a significantly better description of the results than next-to-leading-order QCD calculations, unless the latter are matched to a parton shower calculation
Measurement of the b-hadron production cross section using decays to D∗+μ−X final states in pp collisions at √s = 7 TeV with the ATLAS detector
No full textThe b-hadron production cross section is measured with the ATLAS detector in pp collisions at √s = 7 TeV, using 3.3 pb−1 of integrated luminosity, collected during the 2010 LHC run. The b-hadrons are selected by partially reconstructing D∗+μ−X final states. Differential cross sections are measured as functions of the transverse momentum and pseudorapidity. The measured production cross section for a b-hadron with pT > 9 GeV and |η| < 2.5 is 32.7±0.8(stat.)+4.5 −6.8(syst.) μb, higher than the next-to-leading- order QCD predictions but consistent within the experimental and theoretical uncertainties.Facultad de Ciencias Exacta
ATLAS search for new phenomena in dijet mass and angular distributions using pp collisions at √s = 7 TeV
No full textMass and angular distributions of dijets produced in LHC proton-proton collisions at a centre-of-mass energy s√=7s=7TeV have been studied with the ATLAS detector using the full 2011 data set with an integrated luminosity of 4.8 fb−1. Dijet masses up to ~ 4.0 TeV have been probed. No resonance-like features have been observed in the dijet mass spectrum, and all angular distributions are consistent with the predictions of QCD. Exclusion limits on six hypotheses of new phenomena have been set at 95% CL in terms of mass or energy scale, as appropriate. These hypotheses include excited quarks below 2.83 TeV, colour octet scalars below 1.86 TeV, heavy W bosons below 1.68 TeV, string resonances below 3.61 TeV, quantum black holes with six extra space-time dimensions for quantum gravity scales below 4.11 TeV, and quark contact interactions below a compositeness scale of 7.6 TeV in a destructive interference scenario.Fil: Aad, G.. Albert Ludwigs Universität; AlemaniaFil: Abajyan, T.. Universitaet Bonn; AlemaniaFil: Abbott, B.. University of Oklahoma; Estados UnidosFil: Abdallah, J.. Universitat Autònoma de Barcelona; EspañaFil: Abdel Khalek, S.. Universite Paris Sud; FranciaFil: 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: Anduaga, Xabier Sebastian. 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: González Silva, María Laura. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; 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: Otero y Garzon, Gustavo Javier. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Piegaia, Ricardo Nestor. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Romeo, Gaston Leonardo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tripiana, Martin Fernando. 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: Zhuang, X.. Ludwig Maximilians Universitat; AlemaniaFil: Zhuravlov, V.. Max-Planck Institut für Physik; AlemaniaFil: Zibell, A.. Ludwig Maximilians Universitat; AlemaniaFil: Zieminska, D.. Indiana University; Estados UnidosFil: Zimin, N. I.. Joint Institute for Nuclear Research; RusiaFil: Zimmermann, R.. Universitaet Bonn; AlemaniaFil: Zimmermann, S.. Universitaet Bonn; AlemaniaFil: Zimmermann, S.. Albert Ludwigs Universität; AlemaniaFil: Ziolkowski, M.. Universität Siegen; AlemaniaFil: Zitoun, R.. Université de Savoie; FranciaFil: Živković, L.. Columbia University; Estados UnidosFil: Zmouchko, V. V.. State Research Center Institute for High Energy Physics; RusiaFil: Zobernig, G.. University of Wisconsin; Estados UnidosFil: Zoccoli, A.. Università di Bologna; ItaliaFil: zur Nedden, M.. Humboldt University; AlemaniaFil: Zutshi, V.. Northern Illinois University; Estados UnidosFil: Zwalinski, L.. Cern - European Organization For Nuclear Research; Suiz
- …
