Charm meson resonances in $D to P ell nu$ decays.pdf

a r X i v : h e p - p h / 0 4 1 2 1 4 0 v 3 2 5 J a n 2 0 0 5 Charm meson resonances in D → P?ν decays Svjetlana Fajfer1, 2, ? and Jernej Kamenik1, ? 1J. Stefan Institute, Jamova 39, P. O. Box 3000, 1001 Ljubljana, Slovenia 2Department of Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia (Dated: February 2, 2008) Motivated by recent experimental results we reconsider semileptonic D → P?ν? decays within a model which combines heavy quark symmetry and properties of the chiral Lagrangian. We include excited charm meson states, some of them recently observed, in our Lagrangian and determine their impact on the charm meson semileptonic form factors. We find that the inclusion of excited charm meson states in the model leads to a rather good agreement with the experimental results on the q2 shape of the F+(q 2) form factor. We also calculate branching ratios for all D → P?ν? decays. PACS numbers: 13.20.Fc,12.39.Hg,12.39.Fe,14.40.Lb I. INTRODUCTION The knowledge of the form factors which describe the weak heavy → light semileptonic transitions is very im- portant for the accurate determination of the CKM pa- rameters from the experimentally measured exclusive de- cay rates. A lack of precise information about the shapes of various form factors is thus still the main source of uncertainties especially in these processes. In addition to many studies of exclusive B-meson semileptonic decays there are new interesting results on D-meson semileptonic decays. The CLEO and FOCUS collaborations have studied semileptonic decays D0 → π??+ν and D0 → K??+ν [1, 2]. Their data provides new information on the D0 → π??+ν and D0 → K??+ν form factors. Usually in D semileptonic decays a simple pole parametrization has been used in the past. The results of Refs. [1, 2] for the single pole parameters required by the fit of their data, however, suggest pole masses, which are inconsistent with the physical masses of the lowest lying charm meson resonances. In their anl