338 research outputs found

    CP Measurement in Quantum Teleportation of Neutral Mesons

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    Quantum teleportation using neutral pseudoscalar mesons shows novel connections between particle physics and quantum information. The projection basis, which is crucial in the teleportation process, is determined by the conservation laws of particle physics, and is different from the Bell basis, as in the usual case. Here we show that one can verify the teleportation process by CP measurement. This method significantly simplifies the high energy quantum teleportation protocol. Especially, it is rigorous, and is independent of whether CP is violated in weak decays. This method can also be applied to general verification of Einstein-Podolsky-Rosen correlations in particle physics.Comment: 7 page

    Knotlike Cosmic Strings in The Early Universe

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    In this paper, the knotlike cosmic strings in the Riemann-Cartan space-time of the early universe are discussed. It has been revealed that the cosmic strings can just originate from the zero points of the complex scalar quintessence field. In these strings we mainly study the knotlike configurations. Based on the integral of Chern-Simons 3-form a topological invariant for knotlike cosmic strings is constructed, and it is shown that this invariant is just the total sum of all the self-linking and linking numbers of the knots family. Furthermore, it is also pointed out that this invariant is preserved in the branch processes during the evolution of cosmic strings

    To wet or not to wet: that is the question

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    Wetting transitions have been predicted and observed to occur for various combinations of fluids and surfaces. This paper describes the origin of such transitions, for liquid films on solid surfaces, in terms of the gas-surface interaction potentials V(r), which depend on the specific adsorption system. The transitions of light inert gases and H2 molecules on alkali metal surfaces have been explored extensively and are relatively well understood in terms of the least attractive adsorption interactions in nature. Much less thoroughly investigated are wetting transitions of Hg, water, heavy inert gases and other molecular films. The basic idea is that nonwetting occurs, for energetic reasons, if the adsorption potential's well-depth D is smaller than, or comparable to, the well-depth of the adsorbate-adsorbate mutual interaction. At the wetting temperature, Tw, the transition to wetting occurs, for entropic reasons, when the liquid's surface tension is sufficiently small that the free energy cost in forming a thick film is sufficiently compensated by the fluid- surface interaction energy. Guidelines useful for exploring wetting transitions of other systems are analyzed, in terms of generic criteria involving the "simple model", which yields results in terms of gas-surface interaction parameters and thermodynamic properties of the bulk adsorbate.Comment: Article accepted for publication in J. Low Temp. Phy

    BESII Detector Simulation

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    A Monte Carlo program based on Geant3 has been developed for BESII detector simulation. The organization of the program is outlined, and the digitization procedure for simulating the response of various sub-detectors is described. Comparisons with data show that the performance of the program is generally satisfactory.Comment: 17 pages, 14 figures, uses elsart.cls, to be submitted to NIM

    Direct Measurements of the Branching Fractions for D0Ke+νeD^0 \to K^-e^+\nu_e and D0πe+νeD^0 \to \pi^-e^+\nu_e and Determinations of the Form Factors f+K(0)f_{+}^{K}(0) and f+π(0)f^{\pi}_{+}(0)

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    The absolute branching fractions for the decays D0Ke+νeD^0 \to K^-e ^+\nu_e and D0πe+νeD^0 \to \pi^-e^+\nu_e are determined using 7584±198±3417584\pm 198 \pm 341 singly tagged Dˉ0\bar D^0 sample from the data collected around 3.773 GeV with the BES-II detector at the BEPC. In the system recoiling against the singly tagged Dˉ0\bar D^0 meson, 104.0±10.9104.0\pm 10.9 events for D0Ke+νeD^0 \to K^-e ^+\nu_e and 9.0±3.69.0 \pm 3.6 events for D0πe+νeD^0 \to \pi^-e^+\nu_e decays are observed. Those yield the absolute branching fractions to be BF(D0Ke+νe)=(3.82±0.40±0.27)BF(D^0 \to K^-e^+\nu_e)=(3.82 \pm 0.40\pm 0.27)% and BF(D0πe+νe)=(0.33±0.13±0.03)BF(D^0 \to \pi^-e^+\nu_e)=(0.33 \pm 0.13\pm 0.03)%. The vector form factors are determined to be f+K(0)=0.78±0.04±0.03|f^K_+(0)| = 0.78 \pm 0.04 \pm 0.03 and f+π(0)=0.73±0.14±0.06|f^{\pi}_+(0)| = 0.73 \pm 0.14 \pm 0.06. The ratio of the two form factors is measured to be f+π(0)/f+K(0)=0.93±0.19±0.07|f^{\pi}_+(0)/f^K_+(0)|= 0.93 \pm 0.19 \pm 0.07.Comment: 6 pages, 5 figure

    Study of J/psi decays to Lambda Lambdabar and Sigma0 Sigma0bar

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    The branching ratios and Angular distributions for J/psi decays to Lambda Lambdabar and Sigma0 Sigma0bar are measured using BESII 58 million J/psi.Comment: 11 pages, 5 figure

    Measurements of J/psi Decays into 2(pi+pi-)eta and 3(pi+pi-)eta

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    Based on a sample of 5.8X 10^7 J/psi events taken with the BESII detector, the branching fractions of J/psi--> 2(pi+pi-)eta and J/psi-->3(pi+pi-)eta are measured for the first time to be (2.26+-0.08+-0.27)X10^{-3} and (7.24+-0.96+-1.11)X10^{-4}, respectively.Comment: 11 pages, 6 figure

    Measurement of branching fractions for the inclusive Cabibbo-favored ~K*0(892) and Cabibbo-suppressed K*0(892) decays of neutral and charged D mesons

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    The branching fractions for the inclusive Cabibbo-favored ~K*0 and Cabibbo-suppressed K*0 decays of D mesons are measured based on a data sample of 33 pb-1 collected at and around the center-of-mass energy of 3.773 GeV with the BES-II detector at the BEPC collider. The branching fractions for the decays D+(0) -> ~K*0(892)X and D0 -> K*0(892)X are determined to be BF(D0 -> \~K*0X) = (8.7 +/- 4.0 +/- 1.2)%, BF(D+ -> ~K*0X) = (23.2 +/- 4.5 +/- 3.0)% and BF(D0 -> K*0X) = (2.8 +/- 1.2 +/- 0.4)%. An upper limit on the branching fraction at 90% C.L. for the decay D+ -> K*0(892)X is set to be BF(D+ -> K*0X) < 6.6%

    The σ\sigma pole in J/ψωπ+πJ/\psi \to \omega \pi^+ \pi^-

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    Using a sample of 58 million J/ψJ/\psi events recorded in the BESII detector, the decay J/ψωπ+πJ/\psi \to \omega \pi^+ \pi^- is studied. There are conspicuous ωf2(1270)\omega f_2(1270) and b1(1235)πb_1(1235)\pi signals. At low ππ\pi \pi mass, a large broad peak due to the σ\sigma is observed, and its pole position is determined to be (541±39)(541 \pm 39) - ii (252±42)(252 \pm 42) MeV from the mean of six analyses. The errors are dominated by the systematic errors.Comment: 15 pages, 6 figures, submitted to PL

    Study of J/ψωK+KJ/\psi \to \omega K^+K^-

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    New data are presented on J/ψωK+KJ/\psi \to \omega K^+K^- from a sample of 58M J/ψJ/\psi events in the upgraded BES II detector at the BEPC. There is a conspicuous signal for f0(1710)K+Kf_0(1710) \to K^+K^- and a peak at higher mass which may be fitted with f2(2150)KKˉf_2(2150) \to K\bar K. From a combined analysis with ωπ+π\omega \pi ^+ \pi ^- data, the branching ratio BR(f0(1710)ππ)/BR(f0(1710)KKˉ)BR(f_0(1710)\to\pi\pi)/BR(f_0(1710) \to K\bar K) is <0.11< 0.11 at the 95% confidence level.Comment: 11 pages, 5 figures. Submitted to Phys. Lett.
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