By combining experimentally measured partial branching fractions for the semileptonic decays D→K and D→ with lattice calculations of the formfactors f D→K + (q2) and f D→ + (q2), one can extract the CKM matrix elements |Vcs| and |Vcd|. We are calculating the form factors by using Fermilab charm and asqtad staggered light and strange quarks on 2+1 flavor asqtad staggered ensembles generated by the MILC Collaboration. We vary the light valence quark masses from 0.4ms to 0.05ms (ms is the strange sea-quark mass), and the lattice spacings, from about 0.12 fm to about 0.045 fm. We extrapolate to the physical light-quark mass and the continuum limit using heavy-light meson staggered chiral perturbation theory about the SU(2) and SU(3) limits, compare the resulting (preliminary) form factor shapes with experiment, and discuss our errors.
|Journal||Proceedings of Science|
|Publication status||Published - 2012|
|Event||30th International Symposium on Lattice Field Theory, Lattice 2012 - Cairns, Australia|
Duration: 2012 Jun 24 → 2012 Jun 29
Bibliographical noteFunding Information:
by the Korean government (MEST); this work was supported by grants DE-FG02-91ER40661 (S.G., R.Z.) and DE-FG02-91ER40677 (D.D., R.D.J., A.X.K.) of the U.S. DOE.
From the SU(2) (SU(3)) fits above, the statistical errors in f+D→pi(0) are 4% (4%), and those in f+D→K(0), 2.3% (3%). Important systematic errors are from heavy-quark lattice artifacts, the error in r1, and the error in the axial coupling gpi. Naively updating the gpi error reduces the projected systematics to 3.4% [14, 15]. A careful estimate of all systematics reflecting the entire data set has yet to be made; the difference between our present SU(2) and SU(3) curves is in some cases comparable to the other errors. Fermilab is operated under contract DE-AC02-07CH11359 with the U.S. DOE; J.A.B. is supported by the Creative Research Initiatives Program (2012-0000241) of the NRF grant funded
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