Browsing by Author "Wingate, Matthew"

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Bottom hadron mass splittings in the static limit from 2+1 flavour lattice QCD
(2009-09-01)
Detmold, William
;
Lin, C. -J. David
;
Wingate, Matthew
;
物理研究所
;
Institute of Physics
Dynamical 2 + 1 flavour lattice QCD is used to calculate the splittings between the masses of mesons and baryons containing a single static heavy quark and domain-wall light and strange quarks. Our calculations are based on the dynamical domain-wall gauge field configurations generated by the RBC and UKQCD Collaborations at a spatial Volume of (2.7 fm)(3) and a range of quark masses with a lightest value corresponding to a (partially-quenched) pion mass of 275 MeV. When extrapolated to the physical values of the light quark masses, the results Of Our calculations are generally in good agreement with experimental determinations in the bottom sector. However, the static limit splittings between the Omega(-)(b) baryon and other bottom hadrons tend to slightly underestimate those obtained using the recent D empty set measurement of the Omega(-)(b) (C) 2009 Elsevier B.V. All rights reserved.
Lambda(b) -> Lambda l(+)l(-) form factors and differential branching fraction from lattice QCD
(2013-04-05)
Detmold, William
;
Lin, C. -J. David
;
Meinel, Stefan
;
Wingate, Matthew
;
物理研究所
We present the first lattice QCD determination of the Lambda(b) -> Lambda transition form factors that govern the rare baryonic decays Lambda(b) -> Lambda l(+)l(-) at leading order in heavy-quark effective theory. Our calculations are performed with 2 + 1 flavors of domain-wall fermions, at two lattice spacings and with pion masses down to 227 MeV. Three-point functions with a wide range of source-sink separations are used to extract the ground-state contributions. The form factors are extrapolated to the physical values of the light-quark masses and to the continuum limit. We use our results to calculate the differential branching fractions for Lambda(b) -> Lambda l(+)l(-) with l = e, mu, tau within the standard model. We find agreement with a recent CDF measurement of the Lambda(b) -> Lambda mu(+)mu(-) differential branching fraction. DOI: 10.1103/PhysRevD.87.074502
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.