Lattice 2008
نویسنده
چکیده
Recent measurements of the branching fraction for D s → ν disagree with the Standard Model expectation, which relies on calculations of f D s 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 " f D s puzzle " stands now at 3.5σ , with σ 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 → Kν. 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.
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