Nonleptonic Two Body Decays of Charmed Mesons By
Nonleptonic Two Body Decays of Charmed Mesons By YU Fusheng (于福升) 2011 Cross Strait Meeting on Particle Physics and Cosmology 1
Outline Ø Introduction • phenomenology • heavy flavor physics Ø Generalized Ø Pole Factorization Approach Dominance Model Ø Ø Ø Summary 2
Topological diagrams 3
Introduction Ø Effective Hamiltonian: basic tool to study the hadronic decay of heavy flavor mesons are Wilson coefficients and are four quark operators: 4
Ø The amplitude of Ø The key is to tackle : is üNaïve factorization üGeneralized Factorization üPole dominance model üQCD factorization (QCDF) üPerturbative QCD approach (PQCD) üSoft-collinear effective theory (SCET) ü… 5
Naïve Factorization Ø Assumption: the matrix element is factorized into two parts, Ø Neglect the annihilation and nonfactorization contributions 6
Wilson coefficients for color-favored (T) and color-suppressed (C) processes. Ø are universal and process independent. Ø Difficulties: u are renormalization scale and scheme dependent ufail to describe the color-suppressed decay modes due to the smallness of 7
Generalized Factorization Ø Consider Ø In non-factorization contributions the large-Nc approach, ØA large relative strong phase between diagrams is induced by final-state interactions 8
Annihilation contributions Ø Annihilation diagrams are neglected as an approximation in the factorization model. Ø We will calculate considerable resonant effects of annihilation diagrams in a single pole dominance model. 9
Pole Model Ø Only consider the lowest lying poles Ø Example: 10
Pole Model Ø Ø Ø The weak matrix element is evaluated in the vacuum insertion approximation, The effective strong coupling Inserting the propagator of intermediate state, the decay amplitude is 11
Framework � Annihilation Emission diagrams � Pole Generalized Factorization Model Approach � Consider relative strong phases between topological diagrams � Calculate and the branching ratios of 12
Free Parameters (Wilson Coefficients) 13
14
15
16
17
18
19
Phenomenological Analysis � , large annihilation type contributions agree with the experiment data better than that of the diagrammatic approach. 20
21
Ø Large annihilation type contributions agree with the experiment data. Ø The single pole resonance effect dominates the annihilation type contribution in most decay modes. 22
Ø Small annihilation contributions in this model Ø Due to the smallness of decay constants of intermediate scalar mesons. 23
Summary and Ø are studied on the basis üGeneralized factorization for emission diagrams üPole model for resonance effect of annihilation diagrams üRelative strong phases between topological diagrams Ø Our results agree with experimental data Ø Annihilation small to contributions in pole model , but large to 24
Thank you ! 25
Backup 26
Decay constants and form factors 27
Amplitudes 28
Strong Phase � The amplitudes satisfy the isospin triangle relation but � Besides, importance of inelastic final state interactions of D meson decays in which onshell intermediate states will contribute imaginary parts. 29
Pole Model for D to PP 30
- Slides: 30