3,008 research outputs found

    The AFP Project

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    AFP is a project to extend the diffractive physics programme of the ATLAS experiment by installing new detectors that will be able to tag forward protons scattered at very small angles. This will allow us to study Single Diffraction, Double Pomeron Exchange, Central Exclusive Production and photon-photon processes. This note presents the physics case for the AFP project and briefly describes the proposed detector system.Comment: 10 pages, 8 figures, presented at the Cracow Epiphany Conference on the first year of the LHC, Cracow, Poland, January 10--12, 201

    On the Possibility of Measuring the Single-tagged Exclusive Jets at the LHC

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    The feasibility studies of the measurement of the central exclusive jet production at the LHC using the proton tagging technique are presented. In order to reach the low jet-mass region, single tagged events were considered. The studies were performed at the c.m. energy of 14 TeV and the ATLAS detector, but are also applicable for the CMS-TOTEM experiments. Four data-taking scenarios were considered: AFP and ALFA detectors as forward proton taggers and β\beta^* = 0.55 m and β\beta^* = 90 m optics. After the event selection, the signal-to-background ratio ranges between 5 and 10410^4. Finally, the expected precision of the central exclusive dijet cross-section measurement for data collection period of 100 h is estimated

    Cloning by limiting dilution: an improved estimate that an interesting culture is monoclonal.

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    An interesting culture obtained by limiting dilution is less likely to be monoclonal than a random viable culture. Current practice using limiting dilution to establish monoclonal lines of interesting recombinant DNA or hybridoma-derived organisms overestimates the probability that promising cultures are monoclonal, resulting in inadequate dilutions, with the need for additional subcloning and the avoidable loss (avoidable instability) of interesting lines by overgrowth with uninteresting varieties

    Diffractive Bremsstrahlung at High-β\beta^\star LHC Case Study

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    Feasibility studies of the measurement of the exclusive diffractive bremsstrahlung cross-section in proton-proton scattering at the centre of mass energy of 13 TeV at the LHC are reported. Present studies were performed for the low luminosity LHC running with the betatron function value of 90~m using the ATLAS associated forward detectors ALFA and ZDC. A simplified approach to the event simulation and reconstruction is used. The background influence is also discussed.Comment: 20 pages, 10 figures. arXiv admin note: substantial text overlap with arXiv:1603.0644

    Uncertainties on exclusive diffractive Higgs and jets production at the LHC

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    Two theoretical descriptions of exclusive diffractive jets and Higgs production at the LHC were implemented into the FPMC generator: the Khoze, Martin, Ryskin model and the Cudell, Hern\'andez, Ivanov, Dechambre exclusive model. We then study the uncertainties. We compare their predictions to the CDF measurement and discuss the possibility of constraining the exclusive Higgs production at the LHC with early measurements of exclusive jets. We show that the present theoretical uncertainties can be reduced with such data by a factor of 5

    Exclusive π+π\pi^+\pi^- Production at the LHC with Forward Proton Tagging

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    A process of Central Exclusive π+π\pi^+\pi^- production in proton-proton collisions and its theoretical description is presented. A possibility of its measurement, during the special low luminosity LHC runs, with the help of the ATLAS central detector for measuring pions and the ALFA stations for tagging the scattered protons is studied. A visible cross section is estimated to be 21 μ\mub for s=7\sqrt{s}=7 TeV, which gives over 2000 events for 100 μ\mub1^{-1} of integrated luminosity. Differential distributions in pion pseudorapidities, pion and proton transverse momenta as well as π+π\pi^+\pi^- invariant mass are shown and discussed.Comment: 9 pages, 7 figure

    Feasibility Studies of the Diffractive Bremsstrahlung Measurement at the LHC

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    Feasibility studies of an observation of the exclusive diffractive bremsstrahlung in proton-proton scattering at the LHC are reported. A simplified approach to the photon and the scattered proton energy reconstruction is used. The background influence is discussed.Comment: 15 pages, 6 figure