55,077 research outputs found

    Dilepton Production at Fermilab and RHIC

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    Some recent results from several fixed-target dimuon production experiments at Fermilab are presented. In particular, we discuss the use of Drell-Yan data to determine the flavor structure of the nucleon sea, as well as to deduce the energy-loss of partons traversing nuclear medium. Future dilepton experiments at RHIC could shed more light on the flavor asymmetry and possible charge-symmetry-violation of the nucleon sea. Clear evidence for scaling violation in the Drell-Yan process could also be revealed at RHIC.Comment: 5 pages, talk presented at the RIKEN-BNL Workshop on 'Hard Parton Physics in Nucleus-Nucleus collisions, March 199

    High-Energy Hadron-Induced Dilepton Production from Nucleons and Nuclei

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    We review the production of high-mass lepton pairs in fixed-target experiments, including both Drell-Yan (DY) and heavy quarkonium (J/Psi and Upsilons) production.Comment: 50 pages. To appear in Annual Review of Nuclear and Particle Science, 199

    Continuous-Variable Quantum State Transfer with Partially Disembodied Transport

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    We propose a new protocol of implementing continuous-variable quantum state transfer using partially disembodied transport. This protocol may improve the fidelity at the expense of the introduction of a semi-quantum channel between the parties, in comparison with quantum teleportation using the same strength of entanglement. Depending on the amount of information destroyed in the measurement, this protocol may be regarded as a teleportation protocol (complete destruction of input state), or as a 1M1\to M cloning protocol (partial destruction), or as a direct transmission (no destruction). This scheme can be straightforwardly implemented with the experimentally accessible setup at present.Comment: 4 pages, to appear in Phys. Rev. Let

    Neutron Transversity at Jefferson Lab

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    Nucleon transversity and single transverse spin asymmetries have been the recent focus of large efforts by both theorists and experimentalists. On-going and planned experiments from HERMES, COMPASS and RHIC are mostly on the proton or the deuteron. Presented here is a planned measurement of the neutron transversity and single target spin asymmetries at Jefferson Lab in Hall A using a transversely polarized 3^3He target. Also presented are the results and plans of other neutron transverse spin experiments at Jefferson Lab. Finally, the factorization for semi-inclusive DIS studies at Jefferson Lab is discussed.Comment: 8 pages, 2 figures, proceedings of Como Transversity05 Worksho

    Correlation between incoherent phase fluctuations and disorder in Y1x_{1-x}Prx_xBa2_2Cu3_3O7δ_{7-\delta} epitaxial films from Nernst effect measurements

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    Measurements of Nernst effect, resistivity and Hall angle on epitaxial films of Y1x_{1-x}Prx_xBa2_2Cu3_3O7δ_{7-\delta}(Pr-YBCO, 0x\leq x\leq0.4) are reported over a broad range of temperature and magnetic field. While the Hall and resistivity data suggest a broad pseudogap regime in accordance with earlier results, these first measurements of the Nernst effect on Pr-YBCO show a large signal above the superconducting transition temperature(Tc_c). This effect is attributed to vortex-like excitations in the phase incoherent condensate existing above Tc_c. A correlation between disorder and the width of the phase fluctuation regime has been established for the YBCO family of cuprates, which suggests a Tc_c\approx110K for disorder-free YBa2_2Cu3_3O7δ_{7-\delta}.Comment: 5 pages, 6 figure

    Experimental Demonstration of Quantum State Multi-meter and One-qubit Fingerprinting in a Single Quantum Device

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    We experimentally demonstrate in NMR a quantum interferometric multi-meter for extracting certain properties of unknown quantum states without resource to quantum tomography. It can perform direct state determinations, eigenvalue/eigenvector estimations, purity tests of a quantum system, as well as the overlap of any two unknown quantum states. Using the same device, we also demonstrate one-qubit quantum fingerprinting

    Hardy's Paradox for High-Dimensional Systems: Beyond Hardy's Limit

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    Hardy's proof is considered the simplest proof of nonlocality. Here we introduce an equally simple proof that (i) has Hardy's as a particular case, (ii) shows that the probability of nonlocal events grows with the dimension of the local systems, and (iii) is always equivalent to the violation of a tight Bell inequality.Comment: REVTeX4, 5 pages, 1 figure. Typo in Eq. (17) corrected. Ref. [5] complete

    Magnitude and Sign Correlations in Heartbeat Fluctuations

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    We propose an approach for analyzing signals with long-range correlations by decomposing the signal increment series into magnitude and sign series and analyzing their scaling properties. We show that signals with identical long-range correlations can exhibit different time organization for the magnitude and sign. We find that the magnitude series relates to the nonlinear properties of the original time series, while the sign series relates to the linear properties. We apply our approach to the heartbeat interval series and find that the magnitude series is long-range correlated, while the sign series is anticorrelated and that both magnitude and sign series may have clinical applications.Comment: 4 pages,late

    Anomalous Meissner effect in pnictide superconductors

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    The Meissner effect has been studied in Ba(Fe0.926Co0.074)2As2 and Ba0.6K0.4Fe2As2 single crystals and compared to well known, type-II superconductors LuNi2B2C and V3Si. Whereas flux penetration is mostly determined by the bulk pinning (and, perhaps, surface barrier) resulting in a large negative magnetization, the flux expulsion upon cooling in a magnetic field is very small, which could also be due to pinning and/or surface barrier effects. However, in stark contrast with the expected behavior, the amount of the expelled flux increases almost linearly with the applied magnetic field, at least up to our maximum field of 5.5 T, which far exceeds the upper limit for the surface barrier. One interpretation of the observed behavior is that there is a field-driven suppression of magnetic pair-breaking
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