Heavy To Light Vector Meson Decays Inclusively Related Research

The heavy to light meson decays have attracted much attention and play a very important role in testing the standard model, determining the basic parameters and probing possible new physics beyond the SM. Compared with inclusive decays, the exclusive decays are clean in experiments but difficult in theoretical calculations due to the requirement of knowledge of non-perturbative QCD. By using the effective hamiltonian method, the per-turbative and non-perturbative effects can be dealt with separately which are contained in the wilson coefficients and operator matrix elements respectively. The Wilson coefficients can be calculated by perturbation theory. But for the operator matrix element, it is necessary to use other methods to calculate. For the hadrons containing one heavy quark, one can use the heavy quark effective Field theory （HQEFT） to deal with. By using the heavy quark effective field theory （HQEFT）, one can expand the operator matrix elements over1/mQ （m（?） denoting the mass of heavy quark） and the calculations are simplified significantly.In this thesis, the Dâ†'K’tv decays are investigated via light cone sum rules and heavy quark expansion to next leading order in the frame work of HQEFT. The contents include the following two aspects:·Transition form factors:For the heavy to light meson semileptonic decays, there is only one meson in the final states and the corresponding operator matrix elements can be parameterized in terms of transition form factors. The Dâ†'K transition form factors are calculated by using the light cone sum rules and heavy quark expansion to next leading order in the framework of HQEFT. In this process, the K meson light cone distribution amplitudes are considered to twist3. It is found that the contributions from next leading order are significantly, around10%-20%of the leading order and therefore can not be neglected. Two free parameters s⁰, T are involved in the calculations, so is related to the threshold energy of D meson and T is the Borel transformation parameter. Due to the fact that the contributions from leading and next leading order are calculated separately, different values for so, T are allowed. The uncertainties of transition form factors mainly come from the so for the leading order contribution and around10%.·Heavy to light meson semileptonic decays:Based the calculations above, the Dâ†'K’（?）v decays are investi-gated. The branching ratio for D+â†'K⁰*（?）+vis （3.60⁺0.37₀.41）%, which is consistent with the current experimental value （3.68±0.21）%.