814 research outputs found

    Allowed slepton intergenerational mixing in light of light element abundances

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    We studied allowed region on the intergenerational mixing parameters of sleptons from a viewpoint of big-bang nucleosynthesis in a slepton-neutralino coannihilation scenario. In this scenario, 7^7Li and 6^6Li problems can be solved by considering exotic reactions caused by bound-state effects with a long-lived slepton. Light element abundances are calculated as functions of the relic density and lifetime of the slepton which considerably depend on the intergenerational mixing parameters. Compared with observational light element abundances, we obtain allowed regions on the intergenerational mixing. Ratio of selectron component to stau component, cec_e, is allowed in 2×1011ce2×1092\times 10^{-11} \lesssim c_e \lesssim 2\times 10^{-9} with solving both the 7^7Li and 6^6Li problems. Similarly, the ratio for smuon, cμc_{\mu}, is allowed in 107cμ5×105%2\times 10^{-7} \lesssim c_{\mu} \lesssim 5\times 10^{-5} for mass difference between slepton and neutralino, which is smaller than muon mass, and %10^{-11}\lesssim c_{\mu} \lesssim 2\times 10^{-10} for the mass difference in range between muon mass and 125 MeV. We also discuss collider signatures of the slepton decays. We find characteristic double peaks in momentum distribution of event number of the slepton decays with allowed mixing parameters. Discoveries of the double peaks at future collider experiments should confirm our scenario.Comment: 10 pages, 6 figure

    First-principles method justifying the Dieke diagram and beyond

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    We present a method to determine the model Hamiltonians to treat rare-earth multiplets in solids from the results of the quasiparticle self-consistent \textit{GW} (QSGW) method. We apply the method to trivalent Eu compounds EuCl3_3, EuN, and Eu-doped GaN after examining free rare-earth ions. We solve the model Hamiltonian by the exact diagonalization. Our results justify applying the Dieke diagram to ions in solid, while its limitation is clarified. In particular, we show that the crystal fields cause sizable breaking of the Russell-Saunders coupling.Comment: 7 pages, 3 figures, 2 table

    Development of ballast water treatment technology by mechanochemical cavitations

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    In order to solve environmental problems caused by ballast water, which is a serious problem worldwide, ballast water purification using cavitation was investigated. Previously, only the collapse pressure of cavitation was used for the treatment of planktons. In this study, however, processing by cavitation containing a chemical and the mechanical processing of cavitation were applied. A Venturi nozzle and an ejector nozzle were used to inject sodium hypochlorite. It was found that the ejector nozzle had higher processing performance than the Venturi nozzle, and was effective for high flow rates of ballast water. It was clarified that high plankton extinction ratios could be obtained using mechanochemical cavitation provided by ejector nozzles.http://deepblue.lib.umich.edu/bitstream/2027.42/84238/1/CAV2009-final37.pd

    User-Adaptive A Posteriori Restoration for Incorrectly Segmented Utterances in Spoken Dialogue Systems

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    Ideally, the users of spoken dialogue systems should be able to speak at their own tempo. Thus, the systems needs to interpret utterances from various users correctly, even when the utterances contain pauses. In response to this issue, we propose an approach based on a posteriori restoration for incorrectly segmented utterances. A crucial part of this approach is to determine whether restoration is required. We use a classification-based approach, adapted to each user. We focus on each user’s dialogue tempo, which can be obtained during the dialogue, and determine the correlation between each user’s tempo and the appropriate thresholds for classification. A linear regression function used to convert the tempos into thresholds is also derived. Experimental results show that the proposed user adaptation approach applied to two restoration classification methods, thresholding and decision trees, improves classification accuracies by 3.0% and 7.4%, respectively, in cross validation

    Stau relic density at the Big-Bang nucleosynthesis era consistent with the abundance of the light element nuclei in the coannihilation scenario

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    We calculate the relic density of stau at the beginning of the Big-Bang Nucleosynthesis (BBN) era in the coannihilation scenario of minimal supersymmetric standard model (MSSM). In this scenario, stau can be long-lived and form bound states with nuclei. We put constraints on the parameter space of MSSM by connecting the calculation of the relic density of stau to the observation of the light elements abundance, which strongly depends on the relic density of stau. Consistency between the theoretical prediction and the observational result, both of the dark matter abundance and the light elements abundance, requires the mass difference between the lighter stau and the lightest neutralino to be around 100MeV, the stau mass to be 300 -- 400 GeV, and the mixing angle of the left and right-handed staus to be sinθτ=(0.651)\sin\theta_{\tau} = (0.65 \textrm{--} 1).Comment: 9 pages, 5 figures, figure 5 correcte
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