546 research outputs found
Soft QCD with ATLAS Detector at LHC
No full textSoft QCD measurements in proton-proton collisions at = 900 GeV and 7 TeV recorded with the ATLAS detector at the LHC are presented. Charged particle distributions were measured using tracks reconstructed in the ATLAS inner detector. Activity in the underlying event was studied using independent measurements from tracking detectors and calorimeters. Two-particle angular correlations measurement is also presented. Finally, a new measurement of the inelastic cross-section at =7 TeV has been made using events counted by the Minimum Bias trigger. Results are compared to Monte Carlo models
Search for compositeness at LHC
No full textIf leptons and quarks are composite objects built from more fundamental constituents, it may be possible to explore contact interactions at the LHC. We report on the discovery potential for such interactions in processes with dijet and with dimuon final states
Prospect of new physics using neutrino-like signatures with ATLAS at LHC
No full textProspect of new physics using neutrino-like signatures with ATLAS at L
Soft QCD with ATLAS detector
No full textUsing Minimum Bias data recorded in 2010, ATLAS has carried out several studies of the global properties of pp collisions at 7 TeV. Charged particle distributions, underlying events and two particle correlations results are presented. A precise measurement of the total inelastic cross-section is presented in a well-defined fiducial volume, taking advantage of the precise knowledge of the luminosity available from van der Meer scans First detailed studies of diffraction cross-sections are also reported, based on pseudo-rapidity gap distributions
Searches in lepton only final states with ATLAS
No full textWe present the potential of the ATLAS detector to discover a heavy new resonance decaying into lepton pairs, using early LHC data. The unprecedented center of mass energy will allow to explore regions unaccessible for previous experiments, even with small amount of data. Z' in some models, gravitons and technicolor states are used as benchmarks
ATLAS prospects for New Physics using neutrino-like signatures
No full textMany possible extensions to the Standard Model predict new particles and heavy neutrinos. Standard Model neutrinos are invisible to detectors at colliders but they are indirectly detected using the event Missing Transverse Energy MET. Some of the new stable particles are also invisible to detectors and are detected through their MET. In this paper, we discuss how ATLAS is using the MET~ signatures from standard neutrinos or from new particles to prepare for the analysis of the first fb of good data at 14TeV in view of discovering new physics beyond the Standard Model
Proton structure impact on sensitivity to extra-dimensions at LHC
No full textThe LHC data will provide sensitivity to an unification of the couplings at low energies in the range 10-100 TeV. It is demonstrated in this note that the lack of knowledge on the proton structure, specifically its gluon distribution, can lower dramatically the sensitivity of bare cross section measurements to this physics. However, some more elaborated strategies could probably be developped to recover an important part of the sensitivit
Searches in the dilepton final states with ATLAS
No full textWe present the discovery potential of heavy new resonances decaying into dilepton pairs with early LHC data using the ATLAS detector. The dilepton final states are robust channels to analyze because of the simplicity of the event topology. The unprecedented available center-of-mass energy will allow one to probe regions that are simply inaccessible at previous experiments even with modest amounts of data. After studying the Standard Model predictions and the associated uncertainties one can look for significant deviations as indication of Beyond the Standard Model physics (BSM). The focus is to study the prospects for discovering BSM physics in the dilepton final states with an assumed integrated luminosity ranging from 100 ~ to 10 ~
PDF uncertainties in Higgs production at hadron colliders
No full textUsing the new schemes provided by the CTEQ and MRST collaborations and by Alekhin, we analyse the uncertainties due to the parton distribution functions (PDFs) on the next-to-leading-order cross sections of the four main production processes of the Standard Model Higgs boson at the LHC and the Tevatron. In the Higgs mass range where the production rates are large enough, the spread in the uncertainties when the three sets of PDFs are compared is of about 15% in all processes and at both colliders. However, within one given set of PDFs, the deviations from the values obtained with the reference sets are much smaller, being of %), except in the gluon--gluon fusion mechanism at relatively large Higgs boson masses, where they can reach the level of 10% (15%) at the LHC (Tevatron).Using the new schemes provided by the CTEQ and MRST collaborations and by Alekhin, we analyse the uncertainties due to the parton distribution functions (PDFs) on the next-to-leading-order cross sections of the four main production processes of the Standard Model Higgs boson at the LHC and the Tevatron. In the Higgs mass range where the production rates are large enough, the spread in the uncertainties when the three sets of PDFs are compared is of about 15% in all processes and at both colliders. However, within one given set of PDFs, the deviations from the values obtained with the reference sets are much smaller, being of %), except in the gluon--gluon fusion mechanism at relatively large Higgs boson masses, where they can reach the level of 10% (15%) at the LHC (Tevatron).Using the new schemes provided by CTEQ and MRST Collaborations and by Alekhin, we analyze the uncertainties due to the parton distribution functions (PDFs) on the next-to-leading-order cross sections of the four main production processes of the Standard Model Higgs boson at the LHC and the Tevatron. In the Higgs mass range where the production rates are large enough, the spread in the uncertainties when the three sets of PDFs are compared is of about 15% in all processes and at both colliders. However, within one given set of PDFs, the deviations from the values obtained with the reference sets are much smaller, being of O (5%), except in the gluon–gluon fusion mechanism at relatively large Higgs boson masses, where they can reach the level of 10% (15%) at the LHC (Tevatron)
Dilepton searches with ATLAS
No full textWe present the discovery potential of heavy new resonances decaying into dilepton pairs with early LHC data using the ATLAS detector. The dilepton final states are robust channels to analyze because of the simplicity of the event topology. The unprecedented available center-of-mass energy will allow one to probe regions that were simply inaccessible at previous experiments even with modest amounts of data. After studying the Standard Model predictions and the associated uncertainties, one can look for significant deviations as indications of Beyond the Standard Model physics (BSM). The focus is to study the prospects for discovering BSM physics in the dilepton final states with an assumed integrated luminosity ranging from 100 pb-1 to 1 fb-1
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