5,007 research outputs found

    Testing Fundamental Symmetries with \Lambda_b \to \Lambda -Vector Decay

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    Putting together kinematical and dynamical analysis, a complete study of the decay channels ΛbΛV(1)\Lambda_b \to {\Lambda} V(1^-), with Λpπ\Lambda \to p {\pi}^- and V(J/ψ)+V (J/\psi) \to {\ell}^+ {\ell}^- or V(ρ0)π+π,V ({\rho}^0) \to {\pi}^+ {\pi}^-, is performed. An intensive use of the helicity formalism is involved on the kinematical side, while on the dynamical side, Heavy Quark Effective Theory (HQET) is applied for an accurate determination of the hadronic matrix elements between the baryons Λb\Lambda_b and Λ\Lambda. Emphasis is put on the major role of the Λb\Lambda_b polarization for constructing T-odd observables and the standard ρ0ω{\rho}^0-{\omega} mixing has the benefit effect of amplifying the process of direct CP violation between ΛbandΛˉb\Lambda_b \mathrm{and} {\bar \Lambda}_b decays.Comment: 47 pages, 10 figures and 3 table

    Better Indoor Climate With Less Energy: European Energy Performance of Building Directive (EPBD)

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    The European Commission's Action Plan on Energy Efficiency (2000) indicated the need for specific measures in the building sector. In response, the European Commission (EC) published the proposed Directive on the Energy Performance of Buildings (EPBD) in May 2001. The European Parliament and Council accepted the text, and it was published in the EU Official Journal in January 2003, at which time the Directive became a European Law. The objective of the EPBD is to promote the improvement of the energy performance of buildings, taking into account outdoor climatic and local conditions, as well as indoor climate requirements. The main objective is to achieve better indoor climate with less energy

    Radioactive ion beam development in Berkeley

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    Two radioactive ion beam projects are under development at the 88" Cyclotron, BEARS (Berkeley Experiment with accelerated radioactive species) and the 14O experiment. The projects are initially focused on the production of 11C and 14O, but it is planned to expand the program to 17F, 18F, 13N and 76Kr. For the BEARS project, the radioactivity is produced in form of either CO2 or N2O in a small medical 10 MeV proton cyclotron. The activity is then transported through a 300 m long He-jet line to the 88" cyclotron building, injected into the AECR-U ion source and accelerated through the 88" cyclotron to energies between 1 to 30 MeV/ nucleon. The 14O experiment is a new experiment at the 88" cyclotron to measure the energy-shape of the beta decay spectrum. For this purpose, a target transfer line and a radioactive ion beam test stand has been constructed. The radioactivity is produced in form of CO in a hot carbon target with a 20 MeV 3He from the 88" Cyclotron. The activity diffuses through an 8m long stainless steel line into the 6 GHz ECR ion source IRIS (Ion source for Radioactive ISotopes). It is then ionized and accelerated to 30 keV to mass separate the 14O and then implanted into a carbon foil. In order to optimize the on-line efficiencies of the LBNL ECR ion sources, off-line ionization efficiency studies are carried out for various gases. A summary of the ionization efficiency measurements is presented

    Direct CP Violation in B decays with rho0-omega Mixing

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    A complete study of the process B to pi+ pi- V(V=1--) is performed both in the framework of the helicity formalism and the effective lagrangian approach. Emphasis is put on the factorization hypothesis and the importance of the rho0- omega mixing in enhancing the direct CP violation. New results involving some branching ratios and the ratio of the Penguin/Tree amplitude are given in details.Comment: 7 pages, 2 figures. Talk oresented by ZJA at the 18th International Workshop on High energy Physics and Quantum Field Theory, QFTHEP004, St-Petersbug, RUSSIA, JUne 17-23, 200

    New measurement of θ13\theta_{13} via neutron capture on hydrogen at Daya Bay

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    This article reports an improved independent measurement of neutrino mixing angle θ13\theta_{13} at the Daya Bay Reactor Neutrino Experiment. Electron antineutrinos were identified by inverse β\beta-decays with the emitted neutron captured by hydrogen, yielding a data-set with principally distinct uncertainties from that with neutrons captured by gadolinium. With the final two of eight antineutrino detectors installed, this study used 621 days of data including the previously reported 217-day data set with six detectors. The dominant statistical uncertainty was reduced by 49%. Intensive studies of the cosmogenic muon-induced 9^9Li and fast neutron backgrounds and the neutron-capture energy selection efficiency, resulted in a reduction of the systematic uncertainty by 26%. The deficit in the detected number of antineutrinos at the far detectors relative to the expected number based on the near detectors yielded sin22θ13=0.071±0.011\sin^22\theta_{13} = 0.071 \pm 0.011 in the three-neutrino-oscillation framework. The combination of this result with the gadolinium-capture result is also reported.Comment: 26 pages, 23 figure
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