出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：Recent measurements of the branching fraction for Ds " !! disagree with the Standard Model
expectation, which relies on calculations of fDs from lattice QCD. This paper uses recent preliminary
measurements from CLEO and a new preliminary lattice-QCD result from this conference
to update the significance of the discrepancy. The “ fDs puzzle” stands now at 3.5", with " predominantly
from the statistical uncertainty of the experiments. New physics scenarios that could
solve the puzzle would also lead to non-Standard amplitudes mediating the semileptonic decays
D " K!!. This paper shows where the new amplitudes enter the differential rate and outlines
where lattice QCD calculations are needed to confront recent and forthcoming measurements.
