Charmed and light pseudoscalar meson decay constants from four-flavor lattice QCD with physical light quarks

A. Bazavov, C. Bernard, J. Komijani, C. M. Bouchard, C. Detar, J. Foley, L. Levkova, D. Du, John W Laiho, A. X. El-Khadra, E. D. Freeland, E. Gámiz, Steven Gottlieb, U. M. Heller, J. Kim, D. Toussaint, A. S. Kronfeld, P. B. Mackenzie, J. N. Simone, R. S. Van De WaterR. Zhou, E. T. Neil, R. Sugar

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100 Scopus citations


We compute the leptonic decay constants fD+, fDs, and fK+ and the quark-mass ratios mc/ms and ms/ml in unquenched lattice QCD using the experimentally determined value of fπ+ for normalization. We use the MILC highly improved staggered quark ensembles with four dynamical quark flavors - up, down, strange, and charm - and with both physical and unphysical values of the light sea-quark masses. The use of physical pions removes the need for a chiral extrapolation, thereby eliminating a significant source of uncertainty in previous calculations. Four different lattice spacings ranging from a≈0.06 to 0.15 fm are included in the analysis to control the extrapolation to the continuum limit. Our primary results are fD+=212.6(0.4)(+1.0-1.2)MeV, fDs=249.0(0.3)(+1.1-1.5)MeV, and fDs/fD+=1.1712(10)(+29-32), where the errors are statistical and total systematic, respectively. The errors on our results for the charm decay constants and their ratio are approximately 2-4 times smaller than those of the most precise previous lattice calculations. We also obtain fK+/fπ+=1.1956(10)(+26-18), updating our previous result, and determine the quark-mass ratios ms/ml=27.35(5)(+10-7) and mc/ms=11.747(19)(+59-43). When combined with experimental measurements of the decay rates, our results lead to precise determinations of the Cabibbo-Kobayashi-Maskawa matrix elements |Vus|=0.22487(51)(29)(20)(5), |Vcd|=0.217(1)(5)(1) and |Vcs|=1.010(5)(18)(6), where the errors are from this calculation of the decay constants, the uncertainty in the experimental decay rates, structure-dependent electromagnetic corrections, and, in the case of |Vus|, the uncertainty in |Vud|, respectively.

Original languageEnglish (US)
Article number074509
JournalPhysical Review D
Issue number7
StatePublished - Oct 30 2014


ASJC Scopus subject areas

  • Nuclear and High Energy Physics

Cite this

Bazavov, A., Bernard, C., Komijani, J., Bouchard, C. M., Detar, C., Foley, J., Levkova, L., Du, D., Laiho, J. W., El-Khadra, A. X., Freeland, E. D., Gámiz, E., Gottlieb, S., Heller, U. M., Kim, J., Toussaint, D., Kronfeld, A. S., Mackenzie, P. B., Simone, J. N., ... Sugar, R. (2014). Charmed and light pseudoscalar meson decay constants from four-flavor lattice QCD with physical light quarks. Physical Review D, 90(7), [074509].