2,469 research outputs found

    The FIRST-Optical-VLA Survey for Lensed Radio Lobes

    Full text link
    We present results from a survey for gravitationally lensed radio lobes. Lensed lobes are a potentially richer source of information about galaxy mass distributions than lensed point sources, which have been the exclusive focus of other recent surveys. Our approach is to identify radio lobes in the FIRST catalog and then search optical catalogs for coincident foreground galaxies, which are candidate lensing galaxies. We then obtain higher-resolution images of these targets at both optical and radio wavelengths, and obtain optical spectra for the most promising candidates. We present maps of several radio lobes that are nearly coincident with galaxies. We have not found any new and unambiguous cases of gravitational lensing. One radio lobe in particular, FOV J0743+1553, has two hot spots that could be multiple images produced by a z=0.19 spiral galaxy, but the lensing interpretation is problematic.Comment: 38 pages, 18 figures, aastex, accepted to A

    Constraints on the R-parity- and Lepton-Flavor-Violating Couplings from B0 Decats to Two Charged Leptons

    Get PDF
    We derive the upper bounds on certain products of R-parity- and lepton-flavor-violating couplings from the decays of the neutral BB meson into two charged leptons. These modes of B0B^0 decays can constrain the product combinations of the couplings with one or more heavy generation indices. We find that most of these bounds are stronger than the previous ones.Comment: Table is changed; version to appear in Phys. Rev.

    Rare radiative B decays to orbitally excited K mesons

    Get PDF
    The exclusive rare radiative B meson decays to orbitally excited axial-vector mesons K_1^*(1270), K_1(1400) and to the tensor meson K_2^*(1430) are investigated in the framework of the relativistic quark model based on the quasipotential approach in quantum field theory. These decays are considered without employing the heavy quark expansion for the s quark. Instead the s quark is treated to be light and the expansion in inverse powers of the large recoil momentum of the final K^{**} meson is used to simplify calculations. It is found that the ratio of the branching fractions of rare radiative B decays to axial vector K^*_1(1270) and K_1(1400) mesons is significantly influenced by relativistic effects. The obtained results for B decays to the tensor meson K_2^*(1430) agree with recent experimental data from CLEO.Comment: 17 pages, revte

    Search for light-to-heavy quark flavor changing neutral currents in νμN\nu _{\mu}N and νˉμN\bar{\nu}_{\mu}N scattering at the Tevatron

    Full text link
    We report on a search for flavor-changing neutral-currents (FCNC) in the production of heavy quarks in deep inelastic νμN\nu_{\mu}N and νˉμN\bar{\nu}% _{\mu}N scattering by the NuTeV experiment at the Fermilab Tevatron. This measurement, made possible by the high-purity NuTeV sign-selected beams, probes for FCNC in heavy flavors at the quark level and is uniquely sensitive to neutrino couplings of potential FCNC mediators. All searches are consistent with zero, and limits on the effective mixing strengths % | V_{uc}| ^{2}, Vdb2| V_{db}| ^{2}, and Vsb2| V_{sb}| ^{2} are obtained

    Supersymmetric Effects on Isospin Symmetry Breaking and Direct CP Violation in BργB \to \rho \gamma

    Full text link
    We argue that one can search for physics beyond the standard model through measurements of the isospin-violating quantity Δ0Γ(Bργ)/2Γ(B0ρ0γ)1\Delta^{-0} \equiv \Gamma(B^- \to \rho^- \gamma)/2\Gamma(B^0 \to \rho^0 \gamma)-1, its charge conjugate Δ+0\Delta^{+0}, and direct CP violation in the partial decay rates of B±ρ±γB^\pm \to \rho^\pm \gamma. We illustrate this by working out theoretical profiles of the charge-conjugate averaged ratio Δ12(Δ+0+Δ0)\Delta \equiv {1 \over 2}(\Delta^{+0} +\Delta^{-0}) and the CP asymmetry ACP(B±ρ±γ)A_{CP}(B^\pm \to \rho^\pm \gamma) in the standard model and in some variants of the minimal supersymmetric standard model. We find that chargino contributions in the large tanβ\tan \beta region may modify the magnitudes and flip the signs of Δ\Delta and ACP(B±ρ±γ)A_{CP}(B^\pm \to \rho^\pm \gamma) compared to their standard-model values, providing an unmistakeable signature of supersymmetry.Comment: 10 pages, 7 figures (requires graphicx

    The CP asymmetry for B--> K^* l^+ l^- decay in the general two Higgs doublet model

    Full text link
    We study CP asymmetry for the exclusive decay B --> K^* l^+ l^- in the two Higgs doublet model with three level flavor changing neutral currents (model III). We analyse the dependency of this quantity to the new phase coming from the complex Yukawa couplings in the theory and we find that there exist a considerable CP violation for the relevant process. Further, we see that the sign of the Wilson coefficient C_7^{eff} can be determined by fixing dilepton mass. Therefore, the future measurements of CP asymmetry for B --> K^* l^+ l^- decay will give a powerful information about the sign of Wilson coefficient C_{7}^{eff} and the new physics beyond the SM.Comment: 22 pages, 8 figure

    Penguins leaving the pole: bound-state effects in B decaying to K* + photon

    Full text link
    Applying perturbative QCD methods recently seen to give a good description of the two body hadronic decays of the B meson, we address the question of bound-state effects on the decay B into K* + gamma. Consistent with most analyses, we demonstrate that gluonic penguins, with photonic bremsstrahlung off a quark, change the decay rate by only a few percent. However, explicit off-shell b-quark effects normally discarded are found to be large in amplitude, although in the standard model accidents of phase minimize the effect on the rate. Using an asymptotic distribution amplitude for the K* and just the standard model, we can obtain a branching ratio of a few times 10^{-5}, consistent with the observed rate.Comment: 12 pages. U. of MD PP \#94-129; DOE/ER/40762-033; WM-94-104. LaTeX, One figure, available by fax or pos

    First Measurement of Gamma(D*+) and Precision Measurement of m_D*+ - m_D0

    Full text link
    We present the first measurement of the D*+ width using 9/fb of e+ e- data collected near the Upsilon(4S) resonance by the CLEO II.V detector. Our method uses advanced tracking techniques and a reconstruction method that takes advantage of the small vertical size of the CESR beam spot to measure the energy release distribution from the D*+ -> D0 pi+ decay. We find Gamma(D*+) = 96 +- 4 (Statistical) +- 22 (Systematic) keV. We also measure the energy release in the decay and compute Delta m = m(D*+) - m(D0) = 145.412 +- 0.002 (Statistical) +- 0.012 (Systematic) MeV/c^2Comment: 24 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, submitted to PR
    corecore