1,513 research outputs found

    CP Phases in Supersymmetric Tri-lepton Signals at the Tevatron

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    We have analyzed the supersymmetric tri-lepton signals for sparticle searches at the Tevatron in the minimal supersymmetric standard model with general CP phases without generational mixing. The CP phases may affect very strongly the chargino and neutralino mass spectrums and σ(ppˉχ~1χ~20)\sigma(p\bar{p}\to\tilde{\chi}^-_1\tilde{\chi}^0_2) as well as B(χ~1χ~10ν){\cal B}(\tilde{\chi}^-_1\to\tilde{\chi}^0_1\ell^-\nu) and B(χ~20χ~10+){\cal B}(\tilde{\chi}^0_2\to\tilde{\chi}^0_1\ell^+\ell^-). Even under the stringent constraints from the electron electric dipole moment the CP phases can lead to a minimum of the tri-lepton event rate for their non-trivial values.Comment: 10 pages, 3 eps figures, largely revised by including the electron EDM constraint

    QCD sum rule analysis of excited Λc\Lambda_c mass parameter

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    The mass parameter of orbitally excited Λc\Lambda_c baryons is calculated by using QCD sum rule in the framework of heavy quark effective theory. Two kinds of interpolating current for the excited heavy baryons are introduced. It is obtained that Λˉ=1.080.104+0.095\bar{\Lambda}=1.08^{+0.095}_{-0.104} GeV for the non-derivative current and Λˉ=1.060.107+0.090\bar{\Lambda}=1.06^{+0.090}_{-0.107} GeV for the current with derivative. These results are consistent with experimental data.Comment: 12 pages, 3 figures, to appear in PL

    Polarization Effects on the e+eW+We+e- \to W^+W^- process with Large Extra Dimensions

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    We study large extra dimension effects on the polarizations of the WW pair and electron beam at the e+eW+We^+ e^-\to W^+ W^- process. It is shown that the measurements of the cross section for transversely polarized WW pair with the right-handed electron beam remarkably enhance the possibilities to see the low scale quantum gravity effects. Higher Linear Collider bounds on the string scale in this model can be obtained by using the left-handed electron beam.Comment: Final version to appear in Phys.Lett.B. More references are adde

    Novel 1.5 GPa-strength with 50%-ductility by transformation-induced plasticity of non-recrystallized austenite in duplex steels

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    Needs for steel designs of ultra-high strength and excellent ductility have been an important issue in worldwide automotive industries to achieve energy conservation, improvement of safety, and crashworthiness qualities. Because of various drawbacks in existing 1.5-GPa-grade steels, new development of formable cold-rolled ultra-high-strength steels is essentially needed. Here we show a plausible method to achieve ultra-high strengths of 1.0~1.5 GPa together with excellent ductility above 50% by actively utilizing non-recrystallization region and TRansformation-Induced Plasticity (TRIP) mechanism in a cold-rolled and annealed Fe-Mn-Al-C-based steel. We adopt a duplex microstructure composed of austenite and ultra-fine ferrite in order to overcome low-yield-strength characteristics of austenite. Persistent elongation up to 50% as well as ultra-high yield strength over 1.4 GPa are attributed to well-balanced mechanical stability of non-crystallized austenite with critical strain for TRIP. Our results demonstrate how the non-recrystallized austenite can be a metamorphosis in 1.5-GPa-grade steel sheet design. ? 2017 The Author(s).114Ysciescopu

    Brane Fluctuation and anomalous muon magnetic moment

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    We study the effects of extra dimensions on the muon anomalous magnetic moment with brane fluctuation. Since the coupling is naturally suppressed if brane fluctuation is considered by exponential softening factor for heavier states, the contribution from the whole Kaluza-Klein graviton tower is shown to be finite. The recent BNL E821 result is accomodated with D=4+δD=4+\delta dimensional gravitational scale, MDM_D, in the range of MD1.05.1M_D \simeq 1.0 - 5.1 TeV (δ=2\delta=2), and MD1.08.0M_D \simeq 1.0 - 8.0 TeV (δ=6\delta=6) with the brane tension parameter f=(4π2τ)1/4f=(4\pi^2 \tau)^{1/4}, in the range f=110f = 1 - 10 TeV.Comment: 8 pages, LaTeX, 2 eps Figures, references added, version to appear in PL

    Chiral perturbation theory vs. vector meson dominance in the decays ϕργγ\phi \to \rho \gamma \gamma and ϕωγγ\phi \to \omega \gamma \gamma

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    It is pointed out that the radiative decays of a ϕ\phi meson, \phirho and \phiom, receive dominant contributions from the pseudoscalar (P=η,ηP = \eta, \eta^{'}) exchanges. Using the vector meson dominance model, we find that B (\phirho) \approx 1.3 \times 10^{-4} and B (\phiom) \approx 1.5 \times 10^{-5}, which are mainly from the η\eta^{'} pole. Thus, these decays are well within the reach of the ϕ\phi factory. Our estimates are a few orders of magnitude larger than the chiral loop contributions in the heavy vector meson chiral lagrangian, which is about ( a few ) ×109\times 10^{-9}.Comment: 10 pages, 2 Encapsuled-Postscript figures, uses epsfig.st

    The dissipative dynamics of the field of two-photon Jaynes-Cummings model with Stark shift in dispersive approximation

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    We present the dissipative dynamics of the field of two-photon Jaynes-Cummings model (JCM) with Stark shift in dispersive approximation and investigate the influence of dissipation on entanglement. We show the coherence properties of the field can be affected by the dissipative cavity when nonlinear two-photon process is involved.Comment: 8 pages,3 figure

    The non-perturbative corrections to the BˉXsγ\bar B \to X_s\gamma photon spectrum in a parton-like model

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    We derive a new parton-like formula, which establishes a simple connection between the electroweak decay rate Γ(BˉXsγ\Gamma (\bar B \to X_s\gamma) and the rate of a free b-quark decay. The main features of our approach are the treatment of the b-quark as an on-mass-shell particle and the inclusion of the effects arising from the b-quark transverse motion in the Bˉ\bar B-meson. Using various b-quark light-front (LF) distribution functions, both phenomenological one and the ones derived from current constituent quark models, and neglecting perturbative corrections we compute the photon energy spectra and the moments of the shape function. It is shown that the parton-like approach is fully consistent with the Heavy Quark Effective Theory (HQET) provided the b-quark constituent mass is redefined in the way similar to that used in HQET to define the pole mass of the b quark. In this way the correction to first order in 1/mb1/m_b can be eliminated from the total width in agreement with the general statement of HQET. We have also found that the photon energy spectra calculated in the LF approach agree well with the ones obtained in the ACM model, provided the same distribution function is used as input in both cases. In spite of the simplicity of the model our results show a fair good agreement both with the HQET predictions and available experimental data.Comment: 14 pages, LaTeX, 3 ps figure

    Dilepton Production at SPS-energy Heavy Ion Collisions

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    The production of dileptons is studied within a hadronic transport model. We investigate the sensitivity of the dilepton spectra to the initial configuration of the hadronic phase in a ultrarelativistic heavy ion collision. Possible in medium correction due to the modifications of pions and the pion form factor in a hadronic gas are discussed.Comment: Dedicated to Gerry Brown in honor of the 32nd celebration of his 39th birthday. 31 pages Latex including 13 eps-figures, uses psfig.sty and epsf.st

    Single-filament Composite MgB2/SUS Ribbons by Powder-In-Tube Process

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    We report the successful fabrication of single-filament composite MgB2/SUS ribbons, as an ultra-robust conductor type, employing the powder-in-tube (PIT) process, by swaging and cold rolling only. The remarkable transport critical current (Ic) of the non-sintered MgB2/SUS ribbon has observed, as an unexpected result. Transport critical currents Ic ~ 316 A at T = 4.2 K and Ic ~ 82 A at T = 20 K were observed at self-field, for the non-sintered composite MgB2/SUS ribbon. In addition, the persistent current density Jp values, that were estimated by Bean formula, were more than ~ 7  105 A/cm2 at T = 5 K, and ~ 1.2  105 A/cm2 at T = 30 K, for the sintered composite MgB2/SUS ribbon, at H = 0 G.Comment: 10 pages, 4 figure
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