647 research outputs found

    Vacuum Fluctuations, Geometric Modular Action and Relativistic Quantum Information Theory

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    A summary of some lines of ideas leading to model-independent frameworks of relativistic quantum field theory is given. It is followed by a discussion of the Reeh-Schlieder theorem and geometric modular action of Tomita-Takesaki modular objects associated with the quantum field vacuum state and certain algebras of observables. The distillability concept, which is significant in specifying useful entanglement in quantum information theory, is discussed within the setting of general relativistic quantum field theory.Comment: 26 pages. Contribution for the Proceedings of a Conference on Special Relativity held at Potsdam, 200

    The split property for locally covariant quantum field theories in curved spacetime

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    The split property expresses the way in which local regions of spacetime define subsystems of a quantum field theory. It is known to hold for general theories in Minkowski space under the hypothesis of nuclearity. Here, the split property is discussed for general locally covariant quantum field theories in arbitrary globally hyperbolic curved spacetimes, using a spacetime deformation argument to transport the split property from one spacetime to another. It is also shown how states obeying both the split and (partial) Reeh–Schlieder properties can be constructed, providing standard split inclusions of certain local von Neumann algebras. Sufficient conditions are given for the theory to admit such states in ultrastatic spacetimes, from which the general case follows. A number of consequences are described, including the existence of local generators for global gauge transformations, and the classification of certain local von Neumann algebras. Similar arguments are applied to the distal split property and circumstances are exhibited under which distal splitting implies the full split property

    Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV

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    A search for a Higgs boson decaying into two photons is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross section of the standard model Higgs boson decaying to two photons. The expected exclusion limit at 95% confidence level is between 1.4 and 2.4 times the standard model cross section in the mass range between 110 and 150 GeV. The analysis of the data excludes, at 95% confidence level, the standard model Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The largest excess of events above the expected standard model background is observed for a Higgs boson mass hypothesis of 124 GeV with a local significance of 3.1 sigma. The global significance of observing an excess with a local significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is estimated to be 1.8 sigma. More data are required to ascertain the origin of this excess.Comment: Submitted to Physics Letters

    Measurement of isolated photon production in pp and PbPb collisions at sqrt(sNN) = 2.76 TeV

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    Isolated photon production is measured in proton-proton and lead-lead collisions at nucleon-nucleon centre-of-mass energies of 2.76 TeV in the pseudorapidity range |eta|<1.44 and transverse energies ET between 20 and 80 GeV with the CMS detector at the LHC. The measured ET spectra are found to be in good agreement with next-to-leading-order perturbative QCD predictions. The ratio of PbPb to pp isolated photon ET-differential yields, scaled by the number of incoherent nucleon-nucleon collisions, is consistent with unity for all PbPb reaction centralities.Comment: Submitted to Physics Letters

    In vitro evaluation of sustained released matrix tablets containing ibuprofen: a model poorly water-soluble drug

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    ABSTRACT A matrix system was developed that releases ibuprofen (IB) over a 12-hour period and the influence of the polymer type and concentration on the release rate of the drug was evaluated. Tablets containing different concentrations of Carbopol (CP), hydroxypropyl methylcellulose (HPMC), or ethyl cellulose (EC) were prepared using direct compression and the drug content, content uniformity, hardness, friability, dissolution performance, and in vitro release kinetics were examined. Formulated tablets were found to be within acceptable limits for physical and chemical parameters. The release kinetics of the Carbopol(r)971P 8% formulation showed the best linearity (r 2 =0.977) in fitting zero-order kinetics, suggesting the release rate was time independent. The drug release from tablets containing 8% CP was extended over approximately 18 hours and the release kinetics were nearly linear, suggesting that this system has the potential to maintain constant plasma drug concentrations over 12 hours, which could reduce the frequency of administration and the occurrence of adverse effects associated with repeated administration of conventional IB tablets

    Determination of the Form Factors for the Decay B0 --> D*-l+nu_l and of the CKM Matrix Element |Vcb|

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    We present a combined measurement of the Cabibbo-Kobayashi-Maskawa matrix element Vcb|V_{cb}| and of the parameters ρ2\rho^2, R1R_1, and R2R_2, which fully characterize the form factors of the B0D+νB^0 \to D^{*-}\ell^{+}\nu_\ell decay in the framework of HQET, based on a sample of about 52,800 B0D+νB^0 \to D^{*-}\ell^{+}\nu_\ell decays recorded by the BABAR detector. The kinematical information of the fully reconstructed decay is used to extract the following values for the parameters (where the first errors are statistical and the second systematic): ρ2=1.156±0.094±0.028\rho^2 = 1.156 \pm 0.094 \pm 0.028, R1=1.329±0.131±0.044R_1 = 1.329 \pm 0.131 \pm 0.044, R2=0.859±0.077±0.022R_2 = 0.859 \pm 0.077 \pm 0.022, F(1)Vcb=(35.03±0.39±1.15)×103\mathcal{F}(1)|V_{cb}| = (35.03 \pm 0.39 \pm 1.15) \times 10^{-3}. By combining these measurements with the previous BABAR measurements of the form factors which employs a different technique on a partial sample of the data, we improve the statistical accuracy of the measurement, obtaining: ρ2=1.179±0.048±0.028,R1=1.417±0.061±0.044,R2=0.836±0.037±0.022,\rho^2 = 1.179 \pm 0.048 \pm 0.028, R_1 = 1.417 \pm 0.061 \pm 0.044, R_2 = 0.836 \pm 0.037 \pm 0.022, and F(1)Vcb=(34.68±0.32±1.15)×103. \mathcal{F}(1)|V_{cb}| = (34.68 \pm 0.32 \pm 1.15) \times 10^{-3}. Using the lattice calculations for the axial form factor F(1)\mathcal{F}(1), we extract Vcb=(37.74±0.35±1.25±1.441.23)×103|V_{cb}| =(37.74 \pm 0.35 \pm 1.25 \pm ^{1.23}_{1.44}) \times 10^{-3}, where the third error is due to the uncertainty in F(1)\mathcal{F}(1)
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