The decays D ∗ → Dπ and D ∗ → Dγ are well described by heavy meson chiral perturbation theory. With the recent measurement of B(D ∗+ → D +γ), the D ∗0, D ∗+ and D s∗ branching fractions can be used to extract the D ∗Dπ and D ∗Dγ couplings g and β. The D ∗ → Dγ decays receive important corrections at order √ mq and, from the heavy quark magnetic moment, at order 1/ mc. Here all the decay rates are computed to one loop, to first order in mq and 1/ mc, including the effect of heavy meson mass splittings, and the counterterms at order mq. A fit to the experimental data gives two possible solutions, g = 0.27 -0.02-0.02+0.04+0.05, β= 0.85 -0.1 - 0.1+0.2 + 0.3 GeV - or g = 0.76 -0.03 -0.1+0.03+0.2, β = 4.90 -0.3-0.7+0.3+5.0 GeV -1. The first errors are experimental, while the second are estimates of the uncertainty induced by the counterterms. (The experimental limit Γ D ∗+ < 0.13 MeV excludes the g = 0.76 solution.) Predictions for the D ∗ and B ∗ widths are given.
Nuclear Physics B
- Pub Date:
- September 1998
- High Energy Physics - Phenomenology
- 22 pages, 6 figs., minor typos corrected, comment on large Nc scaling of the counterterms added, to appear in Nucl.Phys.B