6,952 research outputs found

    A method for determining CP violating phase γ\gamma

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    A new way of determining the phases of weak amplitudes in charged BB decays based on SU(3) symmetry is proposed. The CP violating phase γ\gamma can now be determined without the previous difficulty associated with electroweak penguins.Comment: 9 pages plus one figure, Revte

    The Rotation of M Dwarfs Observed by the Apache Point Galactic Evolution Experiment

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    We present the results of a spectroscopic analysis of rotational velocities in 714 M dwarf stars observed by the SDSS III Apache Point Galactic Evolution Experiment (APOGEE) survey. We use a template fitting technique to estimate vsiniv\sin{i} while simultaneously estimating logg\log{g}, [M/H][\text{M}/\text{H}], and TeffT_{\text{eff}}. We conservatively estimate that our detection limit is 8 km s1^{-1}. We compare our results to M dwarf rotation studies in the literature based on both spectroscopic and photometric measurements. Like other authors, we find an increase in the fraction of rapid rotators with decreasing stellar temperature, exemplified by a sharp increase in rotation near the M44 transition to fully convective stellar interiors, which is consistent with the hypothesis that fully convective stars are unable to shed angular momentum as efficiently as those with radiative cores. We compare a sample of targets observed both by APOGEE and the MEarth transiting planet survey and find no cases were the measured vsiniv\sin{i} and rotation period are physically inconsistent, requiring sini>1\sin{i}>1. We compare our spectroscopic results to the fraction of rotators inferred from photometric surveys and find that while the results are broadly consistent, the photometric surveys exhibit a smaller fraction of rotators beyond the M44 transition by a factor of 2\sim 2. We discuss possible reasons for this discrepancy. Given our detection limit, our results are consistent with a bi-modal distribution in rotation that is seen in photometric surveys.Comment: 31 pages, 11 figures, 4 tables. Accepted for publication by A

    Electroweak Model Independent Tests for SU(3) Symmetry in Hadronic B Decays

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    We study effects of new physics beyond the Standard Model on SU(3) symmetry in charmless hadronic two body B decays. It is found that several equalities for some of the decay amplitudes, such as A(Bd(Bu)π+π,π+K(πKˉ0))=A(BsK+π,KK+(K0Kˉ0))A(B_d (B_u) \to \pi^+\pi^-,\pi^+ K^- (\pi^- \bar K^0)) =A(B_s \to K^+ \pi^-, K^- K^+ (K^0 \bar K^0)), A(Bdπ+ρ,πρ+,Kρ+,π+K)=A(BsK+ρ,πK+,KK+,K+K)A(B_d \to \pi^+\rho^-, \pi^- \rho^+, K^-\rho^+, \pi^+ K^{*-}) = A(B_s \to K^+ \rho^-, \pi^- K^{*+}, K^- K^{*+}, K^+ K^{*-}), A(Bd(Bu)ρ+ρ,ρ+K(ρKˉ0))=A(BsK+ρ,KK+(K0Kˉ0))A(B_d (B_u) \to \rho^+\rho^-, \rho^+ K^{*-}(\rho^- \bar K^{*0})) =A(B_s \to K^{*+} \rho^-, K^{*-} K^{*+} (K^{*0} \bar K^{*0})), predicted by SU(3) symmetry in the SM are not affected by new physics. These relations provide important electroweak model independent tests for SU(3) symmetry in B decays.Comment: 4 pages, revte

    Invisible Higgs boson, continuous mass fields and unHiggs mechanism

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    We explore the consequences of an electroweak symmetry breaking sector which exhibits approximately scale invariant dynamics -- i.e., nontrivial fixed point behavior, as in unparticle models. One can think of an unHiggs as a composite Higgs boson with a continuous mass distribution. We find it convenient to represent the unHiggs in terms of a Kallen-Lehmann spectral function, from which it is simple to verify the generation of gauge boson and fermion masses, and unitarization of WW scattering. We show that a spectral function with broad support, which corresponds to approximate fixed point behavior over an extended range of energy, can lead to an effectively invisible Higgs particle, whose decays at LEP or LHC could be obscured by background.Comment: 8 page

    Hybrid vehicle assessment. Phase 1: Petroleum savings analysis

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    The results of a comprehensive analysis of near term electric hybrid vehicles are presented, with emphasis on their potential to save significant amounts of petroleum on a national scale in the 1990s. Performance requirements and expected annual usage patterns of these vehicles are first modeled. The projected U.S. fleet composition is estimated, and conceptual hybrid vehicle designs are conceived and analyzed for petroleum use when driven in the expected annual patterns. These petroleum consumption estimates are then compared to similar estimates for projected 1990 conventional vehicles having the same performance and driven in the same patterns. Results are presented in the form of three utility functions and comparisons of sevral conceptual designs are made. The Hybrid Vehicle (HV) design and assessment techniques are discussed and a general method is explained for selecting the optimum energy management strategy for any vehicle mission battery combination. Conclusions and recommendations are presented, and development recommendations are identified

    CP Violation in a Multi-Higgs Doublet Model

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    We study CP violation in a multi-Higgs doublet model based on a S3×Z3S_3 \times Z_3 horizontal symmetry. We consider two mechanisms for CP violation in this model: a) CP violation due to complex Yukawa couplings; and b) CP violation due to scalar-pseudoscalar mixings. We find that the predictions for ϵ/ϵ\epsilon'/\epsilon, CP violation in B decays and the electric dipole moments of neutron and electron are different between these two mechanisms. These predictions are also dramatically different from the minimal Standard Model predictions.Comment: 17 pages + one figure, Revtex. Talk presented by Deshpande at the Conference WHEPP-3, December 199

    Prospects for Direct CP Violaton in Exclusive and Inclusive Charmless B decays

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    Within the Standard Model, CP rate asymmetries for BKπ+,0B\to K^-\pi^{+,0} could reach 10%. With strong final state phases, they could go up to 20--30%, even for Kˉ0π\bar K^0\pi^- mode which would have opposite sign. We can account for Kπ+K^-\pi^{+}, Kˉ0π\bar K^0\pi^- and ϕK\phi K rate data with new physics enhanced color dipole coupling and destructive interference. Asymmetries could reach 40--60% for KπK\pi and ϕK\phi K modes and are all of the same sign. We are unable to account for Kπ0K^-\pi^0 rate. Our inclusive study supports our exclusive results.Comment: Minor changes, correct a small bug in Fig. 1(b). Version to appear in Phys. Rev. Let
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