243 research outputs found

    The Landau Pole and Zâ€ČZ^{\prime} decays in the 331 bilepton model

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    We calculate the decay widths and branching ratios of the extra neutral boson Zâ€ČZ^{\prime} predicted by the 331 bilepton model in the framework of two different particle contents. These calculations are performed taken into account oblique radiative corrections, and Flavor Changing Neutral Currents (FCNC) under the ansatz of Matsuda as a texture for the quark mass matrices. Contributions of the order of 10−1−10−210^{-1}-10^{-2} are obtained in the branching ratios, and partial widths about one order of magnitude bigger in relation with other non- and bilepton models are also obtained. A Landau-like pole arise at 3.5 TeV considering the full particle content of the minimal model (MM), where the exotic sector is considered as a degenerated spectrum at 3 TeV scale. The Landau pole problem can be avoid at the TeV scales if a new leptonic content running below the threshold at % 3 TeV is implemented as suggested by other authors.Comment: 20 pages, 5 figures, LaTeX2

    Semiseparable integral operators and explicit solution of an inverse problem for the skew-self-adjoint Dirac-type system

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    Inverse problem to recover the skew-self-adjoint Dirac-type system from the generalized Weyl matrix function is treated in the paper. Sufficient conditions under which the unique solution of the inverse problem exists, are formulated in terms of the Weyl function and a procedure to solve the inverse problem is given. The case of the generalized Weyl functions of the form ϕ(λ)exp⁥{−2iλD}\phi(\lambda)\exp\{-2i\lambda D\}, where ϕ\phi is a strictly proper rational matrix function and D=D∗≄0D=D^* \geq 0 is a diagonal matrix, is treated in greater detail. Explicit formulas for the inversion of the corresponding semiseparable integral operators and recovery of the Dirac-type system are obtained for this case

    Cerebral perfusion in sepsis

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    This article is one of ten reviews selected from the Yearbook of Intensive Care and Emergency Medicine 2010 (Springer Verlag) and co-published as a series in Critical Care. Other articles in the series can be found online at http://ccforum.com/series/yearbook. Further information about the Yearbook of Intensive Care and Emergency Medicine is available from http://www.springer.com/series/2855

    Search for Λc+→pK+π−\Lambda_c^+ \to p K^+ \pi^- and Ds+→K+K+π−D_s^+ \to K^+ K^+ \pi^- Using Genetic Programming Event Selection

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    We apply a genetic programming technique to search for the double Cabibbo suppressed decays Λc+→pK+π−\Lambda_c^+ \to p K^+ \pi^- and Ds+→K+K+π−D_s^+ \to K^+ K^+ \pi^-. We normalize these decays to their Cabibbo favored partners and find BR(\text{BR}(\Lambda_c^+ \to p K^+ \pi^-)/BR()/\text{BR}(\Lambda_c^+ \to p K^- \pi^+)=(0.05±0.26±0.02)) = (0.05 \pm 0.26 \pm 0.02)% and BR(\text{BR}(D_s^+ \to K^+ K^+ \pi^-)/BR()/\text{BR}(D_s^+ \to K^+ K^- \pi^+)=(0.52±0.17±0.11)) = (0.52\pm 0.17\pm 0.11)% where the first errors are statistical and the second are systematic. Expressed as 90% confidence levels (CL), we find <0.46< 0.46 % and <0.78 < 0.78% respectively. This is the first successful use of genetic programming in a high energy physics data analysis.Comment: 10 page

    Measurement of the branching ratio of the decay D^0 -> \pi^-\mu^+\nu relative to D^0 -> K^-\mu^+\nu

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    We present a new measurement of the branching ratio of the Cabibbo suppressed decay D^0\to \pi^-\mu^+\nu relative to the Cabibbo favored decay D^0\to K^-\mu^+\nu and an improved measurement of the ratio |\frac{f_+^{\pi}(0)}{f_+^{K}(0)}|. Our results are 0.074 \pm 0.008 \pm 0.007 for the branching ratio and 0.85 \pm 0.04 \pm 0.04 \pm 0.01 for the form factor ratio, respectively.Comment: 13pages, 3 figure

    Study of the decay asymmetry parameter and CP violation parameter in the Lambdac+ --> Lambda pi+ decay

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    Using data from the FOCUS (E831) experiment at Fermilab, we present a new measurement of the weak decay-asymmetry parameter alpha(Lambdac) in Lambdac --> Lambda pi decay. Comparing particle with antiparticle decays, we obtain the first measurement of the CP violation parameter : A = [alpha(Lambdac)+alpha(antiLambda_c)]/[alpha(Lambdac)-alpha(antiLambda_c)]. We obtain alpha(Lambdac)=-0.78+-0.16+-0.13 and A = -0.07+-0.19+-0.12 where errors are statistical and systematic.Comment: 18 pages, to be submitted to Phys. Lett. B For a list of the FOCUS collaboration, see http://www-focus.fnal.gov/authors.htm

    Search for T Violation in Charm Meson Decays

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    Using data from the FOCUS (E831) experiment, we have searched for T violation in charm meson decays using the four-body decay channels D0→K−K+π−π+D^0 \to K^-K^+\pi^-\pi^+, D+→KS0K+π−π+D^+ \to K^0_SK^+\pi^-\pi^+, and Ds+→KS0K+π−π+D^+_s \to K^0_SK^+\pi^-\pi^+. The T violation asymmetry is obtained using triple-product correlations and assuming the validity of the CPT theorem. We find the asymmetry values to be ATviol(D0)=0.010±0.057(stat.)±0.037(syst.)A_Tviol (D^0) = 0.010 \pm 0.057(stat.) \pm 0.037(syst.), ATviol(D+)=0.023±0.062(stat.)±0.022(syst.)A_Tviol (D^+) = 0.023 \pm 0.062(stat.) \pm 0.022(syst.), and ATviol(Ds+)=−0.036±0.067(stat.)±0.023(syst.)A_Tviol (D^+_s) = -0.036 \pm 0.067(stat.) \pm 0.023(syst.). Each measurement is consistent with no T violation. New measurements of the CP asymmetries for some of these decay modes are also presented.Comment: 17 pages,6 figures,submitted to Phys.Lett.

    Hadronic Mass Spectrum Analysis of D+ into K- pi+ mu+ nu Decay and Measurement of the K*(892)^0 Mass and Width

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    We present a Kpi mass spectrum analysis of the four-body semileptonic charm decay D+ into K- pi+ mu+ nu in the range of 0.65 GeV < mKpi < 1.5 GeV. We observe a non-resonant contribution of 5.30 +- 0.74 +0.99 -0.51 % with respect to the total D+ into K- pi+ mu+ nu decay. For the K*(892)^0 resonance, we obtain a mass of 895.41 +- 0.32 +0.35 -0.36 MeV, a width of 47.79 +- 0.86 +1.3 -1.1 MeV, and a Blatt-Weisskopf damping factor parameter of 3.96 +- 0.54 +0.72 -0.90 GeV^(-1). We also report 90 % CL upper limits of 4 % and 0.64 % for the branching ratios of D+ into K*(1680)^0 mu+ nu with respect to D+ into K- pi+ mu+ nu and D+ into K*(1430)^0 mu+ nu with respect to D+ into K- pi+ mu+ nu, respectively.Comment: 14 page

    Study of Lambda/c+ Cabibbo Favored Decays Containing a Lambda Baryon in the Final State

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    Using data from the FOCUS experiment (FNAL-E831), we study the decay of Λc+\Lambda^+_c baryons into final states containing a Λ\Lambda hyperon. The branching fractions of Λc+\Lambda^+_c into Λπ+\Lambda \pi^+, Λπ+π+π−\Lambda \pi^+ \pi^+ \pi^- and ΛKˉ0K+\Lambda \bar{K} ^0 K^+ relative to that into pK−π+pK^-\pi^+ are measured to be 0.217±0.013±0.0200.217 \pm 0.013 \pm 0.020, 0.508±0.024±0.0240.508 \pm 0.024 \pm 0.024 and 0.142±0.018±0.0220.142 \pm 0.018 \pm 0.022, respectively. We also report new measurements of Γ(Λc+→Σ0π+)Γ(Λc+→Λπ+)=1.09±0.11±0.19\frac{\Gamma(\Lambda^+_c \to \Sigma^0 \pi^+)}{\Gamma(\Lambda^+_c \to \Lambda \pi^+)} = 1.09 \pm 0.11 \pm 0.19, Γ(Λc+→Σ0π+π+π−)Γ(Λc+→Λπ+π+π−)=0.26±0.06±0.09\frac{\Gamma(\Lambda^+_c \to \Sigma^0 \pi^+\pi^+ \pi^-)}{\Gamma(\Lambda^+_c \to \Lambda \pi^+ \pi^+ \pi^-)} = 0.26 \pm 0.06 \pm 0.09 and Γ(Λc+→Ξ(1690)0(ΛKˉ0)K+)Γ(Λc+→ΛKˉ0K+)=0.33±0.10±0.04\frac{\Gamma(\Lambda^+_c \to \Xi(1690)^0(\Lambda \bar{K} ^0) K^+)}{\Gamma(\Lambda^+_c \to \Lambda \bar{K} ^0 K^+)} = 0.33 \pm 0.10 \pm 0.04. Further, an analysis of the subresonant structure for the Λc+→Λπ+π+π−\Lambda^+_c \to \Lambda \pi^+\pi^+\pi^- decay mode is presented.Comment: 14 pages, 6 figures, 3 tables, Submitted to Physics Letter

    Measurement of the Bs0→J/ψKS0B_s^0\to J/\psi K_S^0 branching fraction

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    The Bs0→J/ψKS0B_s^0\to J/\psi K_S^0 branching fraction is measured in a data sample corresponding to 0.41fb−1fb^{-1} of integrated luminosity collected with the LHCb detector at the LHC. This channel is sensitive to the penguin contributions affecting the sin2ÎČ\beta measurement from B0→J/ψKS0B^0\to J/\psi K_S^0 The time-integrated branching fraction is measured to be BF(Bs0→J/ψKS0)=(1.83±0.28)×10−5BF(B_s^0\to J/\psi K_S^0)=(1.83\pm0.28)\times10^{-5}. This is the most precise measurement to date
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