Charm meson resonances and D to V semileptonic form factors.pdf

a r X i v : h e p - p h / 0 5 0 6 0 5 1 v 3 2 5 A u g 2 0 0 5 Charm meson resonances and D → V semileptonic form factors Svjetlana Fajfer1, 2, 3, ? and Jernej Kamenik2, ? 1Physik Department, Technische Universita?t Mu?nchen, D-85748 Garching, Germany 2J. Stefan Institute, Jamova 39, P. O. Box 3000, 1001 Ljubljana, Slovenia 3Department of Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia (Dated: February 2, 2008) Using limits of large energy effective theory and heavy quark effective theory we propose a simple parametrization of the heavy to light H → V semileptonic form factors. Then we reconsider D → V ?ν? decays within a model which combines heavy meson and chiral symmetry. In our Lagrangians we include contributions coming from excited charm meson states, some of them recently observed. Within this framework we determine all parameters describing the shapes of the form factors and calculate branching ratios and helicity ratios for all D → V ?ν? decays. PACS numbers: 13.20.Fc,13.20.-v,12.39.Hg,12.39.Fe I. INTRODUCTION Presently, one of the most important issues in hadronic physics is the extraction of the CKM parameters from exclusive decays. An essential ingredient in this approach is the knowledge of the form factors’ shapes in heavy to light weak transitions. Usually, the attention has been devoted to B decays and the determination of the phase of the Vub CKM matrix element. At the same time in the charm sector, the most accurate determination of the size of Vcs and Vcd matrix elements is not from a direct measurement, mainly due to theoretical uncertainties in the calculations of the relevant form factors’ shapes. Recently CLEO and FOCUS have published interest- ing results on D0 → π??+ν? and D0 → K??+ν? de- cays [1, 2]. Their studies indicate that the single pole parametrization of the relevant form factor cannot ex- plain their data very well, leading to unphysical pole masses. Both experimental groups have also attempted a modifi