10,166 research outputs found

    Heavy Quark Physics From Lattice QCD

    Get PDF
    We review the application of lattice QCD to the phenomenology of b- and c-quarks. After a short discussion of the lattice techniques used to evaluate hadronic matrix elements and the corresponding systematic uncertainties, we summarise results for leptonic decay constants, B--Bbar mixing, semileptonic and rare radiative decays. A discussion of the determination of heavy quark effective theory parameters is followed by an explanation of the difficulty in applying lattice methods to exclusive nonleptonic decays.Comment: 52 pages LaTeX with 10 eps files. Requires: hfsprocl.sty (included) plus axodraw.sty, rotating.sty and array.sty. To appear in Heavy Flavours (2nd edition) edited by A J Buras and M Lindner (World Scientific, Singapore). Revised version corrects typo in axis labelling of Fig 1

    A dynamical and kinematical model of the Galactic stellar halo and possible implications for galaxy formation scenarios

    Full text link
    We re-analyse the kinematics of the system of blue horizontal branch field (BHBF) stars in the Galactic halo (in particular the outer halo), fitting the kinematics with the model of radial and tangential velocity dispersions in the halo as a function of galactocentric distance r proposed by Sommer-Larsen, Flynn & Christensen (1994), using a much larger sample (almost 700) of BHBF stars. The basic result is that the character of the stellar halo velocity ellipsoid changes markedly from radial anisotropy at the sun to tangential anisotropy in the outer parts of the Galactic halo (r greater than approx 20 kpc). Specifically, the radial component of the stellar halo's velocity ellipsoid decreases fairly rapidly beyond the solar circle, from approx 140 +/- 10 km/s at the sun, to an asymptotic value of 89 +/- 19 km/s at large r. The rapid decrease in the radial velocity dispersion is matched by an increase in the tangential velocity dispersion, with increasing r. Our results may indicate that the Galaxy formed hierarchically (partly or fully) through merging of smaller subsystems - the 'bottom-up' galaxy formation scenario, which for quite a while has been favoured by most theorists and recently also has been given some observational credibility by HST observations of a potential group of small galaxies, at high redshift, possibly in the process of merging to a larger galaxy (Pascarelle et al 1996).Comment: Latex, 16 pages. 2 postscript figures. Submitted to the Astrophysical Journal. also available at http://astro.utu.fi/~cflynn/outerhalo.htm

    Food Chain Disruptions and Trade: The Importance of North American Market Integration

    Get PDF
    Food Consumption/Nutrition/Food Safety, International Relations/Trade,

    Quark model study of the semileptonic B -> pi decay

    Full text link
    The semileptonic decay B->pi is studied starting from a simple quark model and taking into account the effect of the B* resonance. A novel, multiply subtracted, Omn\`es dispersion relation has been implemented to extend the predictions of the quark model to all physical q^2 values. We find |V_{ub}|=0.0034 +/- 0.0003(exp.)+/- 0.0007(theory), in good agreement with experiment.Comment: Three pages, two figures. To appear in the proceedings of Quark Confinament and Hadron Spectrum VII. Azores, September 200

    K→(ππ)I=2K\to(\pi\pi)_{I=2} decays and twisted boundary conditions

    Full text link
    We propose a new method to evaluate the Lellouch-L\"uscher factor which relates the ΔI=3/2\Delta I=3/2 K→ππK\to\pi\pi matrix elements computed on a finite lattice to the physical (infinite-volume) decay amplitudes. The method relies on the use of partially twisted boundary conditions, which allow the s-wave ππ\pi\pi phase shift to be computed as an almost continuous function of the centre-of-mass relative momentum and hence for its derivative to be evaluated. We successfully demonstrate the feasibility of the technique in an exploratory computation.Comment: 19 pages, 7 figure

    Market Integration in the North American Onion Markets: An Empirical Analysis Using Panel Data

    Get PDF
    This study investigates the level of market integration in the North American Onion Markets. A two-sample period analysis shows an increase in the speed of price convergence overtime, suggesting deeper market integration as NAFTA was fully implemented. Further analysis showed that U.S.-Canadian markets have experienced deeper market integration compared with U.S.-Mexican markets as well as Canadian-Mexican markets.market integration, onion markets, panel data, price convergence, Marketing,

    Trade Creation and Trade Diversion in the North American Free Trade Agreement: The Case of Agricultural Sector

    Get PDF
    This paper examines the impact of the U.S.-Mexico trade agreement under NAFTA. The results suggest that U.S. agricultural imports from Mexico have been responsive to tariff rate reductions applied to Mexican products. A 1 percent decrease in tariff rates is associated with an increase in U.S. agricultural imports from Mexico by 3.96 percent in the first six years of NAFTA and by 1.07 percent in the last six years of NAFTA. US imports from Mexico have also been attributable to the pre-NAFTA tariff rates. Overall, the results indicate that the U.S.-Mexico trade agreement under NAFTA has been trade creating rather than trade diverting.International Relations/Trade,
    • 

    corecore