Browsing by Author "Lin, C-J. David"

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Axial Couplings and Strong Decay Widths of Heavy Hadrons
(2012-04-27)
Detmold, William
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Lin, C-J. David
;
Meinel, Stefan
;
物理研究所
;
Institute of Physics
We calculate the axial couplings of mesons and baryons containing a heavy quark in the static limit using lattice QCD. These couplings determine the leading interactions in heavy hadron chiral perturbation theory and are central quantities in heavy quark physics, as they control strong decay widths and the light quark mass dependence of heavy hadron observables. Our analysis makes use of lattice data at six different pion masses, 227 MeV < m(pi) < 352 MeV, two lattice spacings, a = 0.085, 0.112 fm, and a volume of (2.7 fm)(3). Our results for the axial couplings are g(1) = 0.449(51), g(2) = 0.84(20), and g(3) = 0.71(13), where g(1) governs the interaction between heavy-light mesons and pions and g(2,3) are similar couplings between heavy-light baryons and pions. Using our lattice result for g(3), and constraining 1/m(Q) corrections in the strong decay widths with experimental data for Sigma((*))(c) decays, we obtain Gamma[Sigma((*))(b) -> Lambda(b)pi(+/-)] = 4.2(1.0), 4.8(1.1), 7.3(1.6), 7.8(1.8) MeV for the Sigma(+)(b), Sigma(-)(b), Sigma(b)*(+), Sigma(b)*(-) initial states, respectively. We also derive upper bounds on the widths of the Xi'(()(b)*()) baryons.
Lambda(b) -> pl(-)(v)over-bar(l) form factors from lattice QCD with static b quarks
(2013-07-23)
Detmold, William
;
Lin, C-J. David
;
Meinel, Stefan
;
Wingate, Matthew
;
物理研究所
We present a lattice QCD calculation of form factors for the decay Lambda(b) -> p mu(-)(v) over bar (mu), which is a promising channel for determining the Cabibbo- Kobayashi-Maskawa matrix element vertical bar V-ub vertical bar at the Large Hadron Collider. In this initial study we work in the limit of static b quarks, where the number of independent form factors reduces to two. We use dynamical domain-wall fermions for the light quarks, and perform the calculation at two different lattice spacings and at multiple values of the light-quark masses in a single large volume. Using our form factor results, we calculate the Lambda(b) -> p mu-(v) over bar (mu) differential decay rate in the range 14 GeV2 <= q(2) <= q(max)(2), and obtain the integral integral(q2max)(14 GeV2) [d Gamma/dq(2)]dq(2)/vertical bar V-ub vertical bar(2) = 15.3 +/- 4.2 ps(-1). Combined with future experimental data, this will give a novel determination of vertical bar V-ub vertical bar with about 15% theoretical uncertainty. The uncertainty is dominated by the use of the static approximation for the b quark, and can be reduced further by performing the lattice calculation with a more sophisticated heavy-quark action.