3,453 research outputs found

    A Preliminary Look at the Physics Reach of a Solar Neutrino TPC: Time-Independent Two Neutrino Oscillations

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    This paper will discuss the physics reach of a solar neutrino TPC containing many tons of He4 under high pressure. Particular attention is given to the LMA and SMA solutions, which are allowed by current data, and which are characterized by a lack of time-dependent phenomena (either summer-winter or day-night asymmetries). In this case, the physics of neutrino masses and mixing is all contained in the energy dependence of the electron neutrino survival probability, (or in its reciprocal, the electron neutrino disappearance probability).Comment: 19 pages, 12 figure

    Improved KL->pi e nu Form Factor and Phase Space Integral with Reduced Model Uncertainty

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    Using the published KTeV sample of 2 million KL-> pi e nu decays and a new form factor expansion with a rigorous bound on higher order terms, we present a new determination of the KL->pi e nu form factor and phase space integral. Compared to the previous KTeV result, the uncertainty in the new form factor expansion is negligible and results in an overall uncertainty in the phase space integral (IKe) that is a factor of two smaller: IKe = 0.15392 +- 0.00048 \.Comment: 3 pages, 2 figures, submitted to PRD Rapid Communicatio

    Measurements of the Decay KLe+eγK_L \to e^+e^-\gamma

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    The E799-II (KTeV) experiment at Fermilab has collected 83262 KLe+eγK_L \to e^+e^-\gamma events above a background of 79 events. We measure a decay width, normalized to the KLπ0π0πD0K_L \to \pi^0\pi^0\pi^0_D (\pi^0 \to \gamma\gamma, \pi^0 to \gamma\gamma, \pi^0_D \to e^+e^-\gamma) decay width, of Γ(\Gamma(K_L \to e^+e^-\gamma)/Γ(KLπ0π0πD0)=(1.3302±0.0046stat±0.0102syst)×103)/\Gamma(K_L \to \pi^0\pi^0\pi^0_D) = (1.3302 \pm 0.0046_{stat} \pm 0.0102_{syst}) \times 10^{-3}. We also measure parameters of two KLγγK_L \gamma^{\ast}\gamma form factor models. In the Bergstrom, Masso, and Singer (BMS) parametrization, we find \caks = -0.517 \pm 0.030_{stat} \pm 0.022_{syst}. We separately fit for the first parameter of the D'Ambrosio, Isidori, and Portoles (DIP) model and find \adip = -1.729 \pm 0.043_{stat} \pm 0.028_{syst}.Comment: 5 pages, 3 figures, submitted to PR

    Dynamic critical behavior of the worm algorithm for the Ising model

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    We study the dynamic critical behavior of the worm algorithm for the two- and three-dimensional Ising models, by Monte Carlo simulation. The autocorrelation functions exhibit an unusual three-time-scale behavior. As a practical matter, the worm algorithm is slightly more efficient than Swendsen-Wang for simulating the two-point function of the three-dimensional Ising model

    Determination of the Parity of the Neutral Pion via the Four-Electron Decay

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    We present a new determination of the parity of the neutral pion via the double Dalitz decay pi^0 -> e+ e- e+ e-. Our sample, which consists of 30511 candidate decays, was collected from K_L -> pi0 pi0 pi0 decays in flight at the KTeV-E799 experiment at Fermi National Accelerator Laboratory. We confirm the negative pi^0 parity, and place a limit on scalar contributions to the pi^0 -> e+ e- e+ e- decay amplitude of less than 3.3% assuming CPT conservation. The pi^0 gamma* gamma* form factor is well described by a momentum-dependent model with a slope parameter fit to the final state phase space distribution. Additionally, we have measured the branching ratio of this mode to be B(pi^0 -> e+ e- e+ e-) = (3.26 +- 0.18) x 10^(-5).Comment: 5 pages, 4 figures. Typographical error in radiative branching ratio (Eq. 6) correcte