1,259 research outputs found

    Heavy Ion Physics at the LHC with the ATLAS Detector

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    The ATLAS detector at CERN will provide a high-resolution longitudinally-segmented calorimeter and precision tracking for the upcoming study of heavy ion collisions at the LHC (sqrt(s_NN)=5520 GeV). The calorimeter covers |eta|<5 with both electromagnetic and hadronic sections, while the inner detector spectrometer covers |eta|<2.5. ATLAS will study a full range of observables necessary to characterize the hot and dense matter formed at the LHC. Global measurements (particle multiplicities, collective flow) will provide access into its thermodynamic and hydrodynamic properties. Measuring complete jets out to 100's of GeV will allow detailed studies of energy loss and its effect on jets. Quarkonia will provide a handle on deconfinement mechanisms. ATLAS will also study the structure of the nucleon and nucleus using forward physics probes and ultraperipheral collisions, both enabled by segmented Zero Degree Calorimeters.Comment: 9 pages, 8 figures, submitted to the Proceedings of Quark Matter 2006, Shanghai, China, November 14-20, 200

    On CP-Odd Effects in K_L \to 2\pi and K^{\pm} \to \pi^{\pm} \pi^{\pm} \pi^{\mp} Decays Generated by Direct CP Violation

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    The amplitudes of the K^{\pm} \to 3\pi and K \to 2\pi decays are expressed in terms of different combinations of one and the same set of CP-conserving and CP-odd parameters. Extracting the magnitudes of these parameters from the data on K \to 2\pi decays, we estimate an expected CP-odd difference between the values of the slope parameters g^+ and g^- of the energy distributions of "odd" pions in K^+ \to \pi^+\pi^+\pi^- and K^- \to \pi^-\pi^-\pi^+ decays.Comment: 12 pages, no figure

    Pion Interactions in Chiral Field Theories

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    We study in various chiral models the pion charge radius, πe3\pi_{e3} form factor ratio, πγγ\pi^\circ \to \gamma \gamma amplitude, charge pion polarizabilities, γγππ\gamma\gamma \to \pi^\circ \pi^\circ amplitude at low energies and the ππ\pi\pi s-wave I = 0 scattering length. We find that a quark-level linear sigma-model approach (also being consistent with tree-level vector meson dominance) is quite compatible with all of the above data.Comment: 12 pages, 9 eps figure

    S-wave Meson-Meson Scattering from Unitarized U(3) Chiral Lagrangians

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    An investigation of the s-wave channels in meson-meson scattering is performed within a U(3) chiral unitary approach. Our calculations are based on a chiral effective Lagrangian which includes the eta' as an explicit degree of freedom and incorporates important features of the underlying QCD Lagrangian such as the axial U(1) anomaly. We employ a coupled channel Bethe-Salpeter equation to generate poles from composed states of two pseudoscalar mesons. Our results are compared with experimental phase shifts up to 1.5 GeV and effects of the eta' within this scheme are discussed.Comment: 18 pages, 6 figure

    Relativistic Effects in the Scalar Meson Dynamics

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    A separable potential formalism is used to describe the ππ\pi\pi and KKK\overline{K} interactions in the scalar-isoscalar states in the energy range from the ππ\pi\pi threshold up to 1.4 GeV. Introduction of relativistic propagators into a system of Lippmann-Schwinger equations leads to a very good description of the data (χ2=0.93\chi^{2}=0.93 per one degree of freedom). Three poles are found in this energy region: fo(500) (M=506±10M=506\pm 10 MeV, Γ=494±5\Gamma=494\pm 5 MeV), fo(975) (M=973±2M=973\pm 2 MeV, Γ=29±2\Gamma=29\pm 2 MeV) and fo(1400) (M=1430±5M=1430\pm 5 MeV, Γ=145±25\Gamma=145\pm 25 MeV). The fo(975) state can be interpreted as a KKK\overline{K} bound state. The fo(500) state may be associated with the often postulated very broad scalar resonance under the KKK\overline{K} threshold (sometimes called σ\sigma or ϵ\epsilon meson). The scattering lengths in the ππ\pi\pi and KKK\overline{K} channels have also been obtained. The relativistic approach provides qualitatively new results (e.g. the appearance of the fo(500)) in comparison with previously used nonrelativistic approach.Comment: 30 pages in LaTeX + 5 figures available on request. Preprint Orsay No IPNO/TH 93-3

    A global fit of ππ\pi\pi and πK\pi K elastic scattering in ChPT with dispersion relations

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    We apply the one-loop results of the SU(3)L×SU(3)RSU(3)_L\times SU(3)_R ChPT suplemented with the inverse amplitude method to fit the available experimental data on ππ\pi\pi and πK\pi K scattering. With esentially only three parameters we describe accurately data corresponding to six different channels, namely (I,J)=(0,0),(2,0),(1,1),(1/2,0),(3/2,0)(I,J)=(0,0), (2,0), (1,1), (1/2,0), (3/2,0) and (1/2,1)(1/2,1). In addition we reproduce the first resonances of the (1,1)(1,1) and (1/2,1)(1/2,1) channel with the right mass corresponding to the ρ\rho and the K(892)K^*(892) particles.Comment: 19 pages, 5 figures available on request, FT/UCM/10/9

    Pion Mass Effects in the Large NN Limit of \chiPT

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    We compute the large NN effective action of the O(N+1)/O(N)O(N+1)/O(N) non-linear sigma model including the effect of the pion mass to order mπ2/fπ2m^2_{\pi}/f_{\pi}^2. This action is more complex than the one corresponding to the chiral limit not only because of the pion propagators but also because chiral symmetry produce new interactions proportional to mπ2/fπ2m^2_{\pi}/f_{\pi}^2. We renormalize the action by including the appropriate counter terms and find the renormalization group equations for the corresponding couplings. Then we estudy the unitarity propierties of the scattering amplitudes. Finally our results are applied to the particular case of the linear sigma model and also are used to fit the pion scattering phase shifts.Comment: FT/UCM/18/9

    The Inverse Amplitude Method in ππ\pi\pi Scattering in Chiral Perturbation Theory to Two Loops

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    The inverse amplitude method is used to unitarize the two loop ππ\pi\pi scattering amplitudes of SU(2) Chiral Perturbation Theory in the I=0,J=0I=0,J=0, I=1,J=1I=1,J=1 and I=2,J=0I=2,J=0 channels. An error analysis in terms of the low energy one-loop parameters lˉ1,2,3,4,\bar l_{1,2,3,4,} and existing experimental data is undertaken. A comparison to standard resonance saturation values for the two loop coefficients bˉ1,2,3,4,5,6\bar b_{1,2,3,4,5,6} is also carried out. Crossing violations are quantified and the convergence of the expansion is discussed.Comment: (Latex, epsfig) 30 pages, 13 figures, 8 table

    Medication Management Models for Polymedicated Home-Dwelling Older Adults With Multiple Chronic Conditions: Protocol of a Systematic Review.

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    Older adults with multiple chronic diseases commonly require complex medication regimes. When combined with frailty, cognitive impairment, and changing pharmacological prescriptions, older adults' polymedication regimes increase the risk of medication-related problems (MRPs) and hospitalization. Effective, well-organized medication management could avoid MRPs and their clinical outcomes. Identify medication management models and analyze their impact on managing and preventing MRPs for polymedicated, home-dwelling older adults. We will conduct a systematic review of published articles in relevant professional scientific journals from inception until March 31, 2019, in the following electronic databases,: Embase; Medline OvidSP; PubMed (NOT Medline[sb]); Cumulative Index to Nursing and Allied Health Literature (CINAHL) EBSCO; PsycINFO OvidSP; Cochrane Library, Wiley; and Web of Science. We will also hand search the bibliographies of all the relevant articles found and search for unpublished studies. We will consider publications in English, French, German, Spanish, Italian, and Portuguese. Retrieved articles will be screened for eligibility. Statistical analyses will be conducted following the recommendations of the Cochrane Handbook for Systematic Reviews of Interventions, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), and Meta-analysis Of Observational Studies in Epidemiology (MOOSE) statements. Data will be analyzed using SPSS Statistics for Windows, version 25.0 (IBM Corp), and Review Manager, version 5.5 (The Nordic Cochrane Centre, The Cochrane Collaboration). A preliminary search in Embase delivered 3272 references. This preliminary search allows us to complete our research strategy with equation development and to search the other databases. Relevant articles identified will allow for searching the reference lists for unpublished studies. The inclusion and exclusion criteria will be rigorously respected in the study selection. The entire study is expected to be completed by January 2020. This review will provide an exhaustive view of medication management models that could be effective for polymedicated, home-dwelling older adults and will allow us to analyze their impact on managing and preventing MRPs. PROSPERO CRD42018117287; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=117287 (Archived by WebCite at http://www.webcitation.org/77fCfbCjT). DERR1-10.2196/13582

    The isospin symmetry breaking effects in Ke4K_{e4} decays

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    The Fermi-Watson theorem is generalized to the case of two coupled channels with different masses and applied to final state interaction in Ke4K_{e4} decays. The impact of considered effect on the phase of the ππ\pi\pi scattering is estimated and shown that it can be crucial for scattering lengths extraction from experimental data on Ke4K_{e4} decays
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