29,568,891 research outputs found

    Filming layers of time in an endangered ecosystem

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    Measurement of the flavour-specific CP-violating asymmetry as sl in B0s decays

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    The CP  -violating asymmetry is studied using semileptonic decays of and mesons produced in pp   collisions at a centre-of-mass energy of 7 TeV at the LHC, exploiting a data sample corresponding to an integrated luminosity of 1.0 fb−1. The reconstructed final states are , with the particle decaying in the ϕπ± mode. The yields are summed over and initial states, and integrated with respect to decay time. Data-driven methods are used to measure efficiency ratios. We obtain , where the first uncertainty is statistical and the second systematic

    New Physics in b --> s bar(s) s Decay

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    We perform a model-independent analysis of the data on branching ratios and CP asymmetries of B→ϕKB\to\phi K and B→η(â€Č)K(∗)B\to\eta^{(')} K^{(*)} modes. The present data is encouraging to look for indirect evidences of physics beyond the Standard Model. We investigate the parameter spaces for different possible Lorentz structures of the new physics four-Fermi interaction. It is shown that if one takes the data at 1σ1\sigma confidence level, only one particular Lorentz structure is allowed. Possible consequences for the BsB_s system are also discussed.Comment: 9 pages, 3 encapsulated figures, minor changes in the text, conclusions unchanged, a few references added, version to appear in PL

    Color suppressed contributions to the decay modes B_{d,s} -> D_{s,d} D_{s,d}, B_{d,s} -> D_{s,d} D^*_{s,d}, and B_{d,s} -> D^*_{s,d} D^*_{s,d}

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    The amplitudes for decays of the type Bd,s→Ds,dDs,dB_{d,s} \to D_{s,d} D_{s,d}, have no factorizable contributions, while Bd,s→Ds,dDs,d∗B_{d,s} \to D_{s,d} D^*_{s,d}, and Bd,s→Ds,d∗Ds,d∗B_{d,s} \to D^*_{s,d} D^*_{s,d} have relatively small factorizable contributions through the annihilation mechanism. The dominant contributions to the decay amplitudes arise from chiral loop contributions and tree level amplitudes which can be obtained in terms of soft gluon emissions forming a gluon condensate. We predict that the branching ratios for the processes Bˉd0→Ds+Ds−\bar B^0_d \to D_s^+ D_s^-, Bˉd0→Ds+∗Ds−\bar B^0_d \to D_s^{+*} D_s^- and Bˉd0→Ds+Ds−∗\bar B^0_d \to D_s^+ D_s^{-*} are all of order (2−3)×10−4(2- 3) \times 10^{-4}, while Bˉs0→Dd+Dd−\bar B^0_s \to D_d^+ D_d^-, Bˉs0→Dd+∗Dd−\bar B^0_s \to D_d^{+*} D_d^- and Bˉs0→Dd+Dd−∗\bar B^0_s \to D_d^+ D_d^{-*} are of order (4−7)×10−3(4- 7) \times 10^{-3}. We obtain branching ratios for two D∗D^*'s in the final state of order two times bigger.Comment: 15 pages, 4 figure

    Coulomb effects in a ballistic one-channel S-S-S device

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    We develop a theory of Coulomb oscillations in superconducting devices in the limit of small charging energy ECâ‰ȘΔE_C \ll \Delta. We consider a small superconducting grain of finite capacity connected to two superconducting leads by nearly ballistic single-channel quantum point contacts. The temperature is supposed to be very low, so there are no single-particle excitations on the grain. Then the behavior of the system may be described as quantum mechanics of the superconducting phase on the island. The Josephson energy as a function of this phase has two minima which become degenerate at the phase difference on the leads equal to π\pi, the tunneling amplitude between them being controlled by the gate voltage at the grain. We find the Josephson current and its low-frequency fluctuations and predict their periodic dependence on the induced charge Qx=CVgQ_x=C V_g with period 2e2e.Comment: 11 pages, REVTeX, 10 figures, uses eps
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