726 research outputs found

    Determination of Integrated Luminosity via W and Z Boson Production with the ATLAS Detector

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    The possibility to determine the recorded integrated luminosity via the measurements of the W and Z boson production cross-sections with the ATLAS detector is discussed. The current results based on 2010 data are briefly summarized. Special attention is drawn to theoretical uncertainties of the measurement. The latter give a large contribution to the systematic uncertainties of the measurements. An outlook on the expected precision of an analysis based on 1fb-1 is given and the implications on a possible luminosity determination are discussed.Comment: presented at the LHC Lumi Days: LHC Workshop on LHC Luminosity Calibration, 13-14 January 2011, CERN, Geneva, Switzerland; CERN-Proceedings-2011-001, pp. 22-2

    Review of single vector boson production in pp collisions at s=7\sqrt{s} = 7 TeV

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    This review summarises the main results on the production of single vector bosons in the Standard Model, both inclusively and in association with light and heavy flavour jets, at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of 7 TeV. The general purpose detectors at this collider, ATLAS and CMS, each recorded an integrated luminosity of 40pb1\approx 40\,{\rm pb^{-1}} and 5fb15\,{\rm fb^{-1}} in the years 2010 and 2011, respectively. The corresponding data offer the unique possibility to precisely study the properties of the production of heavy vector bosons in a new energy regime. The accurate understanding of the Standard Model is not only crucial for searches of unknown particles and phenomena but also to test predictions of perturbative Quantum-Chromo-Dynamics calculations and for precision measurements of observables in the electroweak sector. Results from a variety of measurements in which single W or Z bosons are identified are reviewed. Special emphasis in this review is given to interpretations of the experimental results in the context of state-of-the-art predictions.Comment: 60 pages, 64 figures, For Eur. Phys. J.

    Diboson Production in Proton-Proton Collisions at s=7\sqrt{s}=7 TeV

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    This review article summarizes results on the production cross section measurements of electroweak boson pairs (WWWW, WZWZ, ZZZZ, WγW\gamma and ZγZ\gamma) at the Large Hadron Collider (LHC) in pppp collisions at a center-of-mass energy of s=7\sqrt{s}=7 \TeV. The two general-purpose detectors at the LHC, ATLAS and CMS, recorded an integrated luminosity of 5fb15fb^{-1} in 2011, which offered the possibility to study the properties of diboson production to high precision. These measurements test predictions of the Standard Model (SM) in a new energy regime and are crucial for the understanding and the measurement of the SM Higgs boson and other new particles. In this review, special emphasis is drawn on the combination of results from both experiments and a common interpretation with respect to state-of-the-art SM predictions.Comment: 60 page

    Development and Performance of spark-resistant Micromegas Detectors

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    The Muon ATLAS MicroMegas Activity (MAMMA) focuses on the development and testing of large-area muon detectors based on the bulk-Micromegas technology. These detectors are candidates for the upgrade of the ATLAS Muon System in view of the luminosity upgrade of Large Hadron Collider at CERN (sLHC). They will combine trigger and precision measurement capability in a single device. A novel protection scheme using resistive strips above the readout electrode has been developed. The response and sparking properties of resistive Micromegas detectors were successfully tested in a mixed (neutron and gamma) high radiation field, in a X-ray test facility, in hadron beams, and in the ATLAS cavern. Finally, we introduced a 2-dimensional readout structure in the resistive Micromegas and studied the detector response with X-rays

    Searching for Gravitational Waves with CMS

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    The idea of searching for gravitational waves using cavities in strong magnetic fields has recently received significant attention. Most concepts foresee moderate magnetic fields in rather small volumes, similar to those which are currently employed for axion-like particle searches. We propose to use the magnet system of the Compact Muon Solenoid (CMS) experiment after the high luminosity phase of the LHC as a key component for a future detector for gravitational waves in the MHz frequency range. In this paper we briefly discuss a possible cavity concept which can be integrated into CMS and additionally provide a first estimation of its possible sensitivity.Comment: 4 pages, 2 figure

    From Lost Letters to Conditional E-Mail Responses: A Method to Assess Biased Behavior Online

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    This article introduces the Conditional E-mail Response Technique (CERT) as a systematic, hidden observation technique to measure behavioral tendencies. Although CERT derives from older techniques such as lost-letter/lost-e-mail techniques, we show how CERT is unique: each participant receives several e-mails with varying content, allowing the researcher to observe response rates and valence as a function of the manipulated content. Our study investigated discrimination against foreigners in the apartment rental market in Heidelberg (a German university city) by recording lessors' (non-) responses to 600 e-mails from fake applicants. Each owner (N = 120) received five applications for a one-room apartment via e-mail. Applicants' ethnic identities were communicated through their names. The results showed a remarkable bias against foreign names compared to German names. The response rates for foreign applicants were almost half that for German applicants (response rates were 78% for German names compared to 44-54% for American, Italian, Russian, and Turkish names). The relative risk of a rejecting response was up to eight times higher for e-mails appearing to come from foreigners. Applicants with foreign names were noticeably more likely to receive either no response or a negative response, that is, to have a negative outcome. There were also differences among the foreign applicant groups. We discuss the implications, ethical considerations, and advantages of CERT compared to other related techniques, as well as possible future uses

    The Global Network of Cavities to Search for Gravitational Waves (GravNet): A novel scheme to hunt gravitational waves signatures from the early universe

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    The idea of searching for gravitational waves using cavities in strong magnetic fields has recently received significant attention. Specifically, discussions focus on cavities with relatively small volumes, which are currently employed in the search for axions. In this context, we propose a novel experimental scheme that enables the detection of gravitational waves in the GHz regime, which could originate, for example, from primordial black hole mergers. The scheme is based on synchronous measurements of cavity signals from multiple devices operating in magnetic fields at distant locations. While gravitational wave signatures might be detectable in individual cavities, distinguishing them from noise is highly challenging. By analyzing the correlation among signals from several, possibly geographically separated cavities, it is not only possible to significantly enhance the signal-to-noise ratio but also to investigate the source of those gravitational wave signatures. In the context of this proposal, a first demonstration experiment with one superconducting cavity is currently conducted, which is the basis of the proposed data-analysis approaches. On this basis the prospects of GravNet (Global Network of Cavities to Search for Gravitational Waves) are outlined in the paper.Comment: 9 page