nonleptonic two body decays of charmed mesons

By YU Fusheng (于福升 )

2011 Cross Strait Meeting on Particle Physics and Cosmology1

Introduction

• phenomenology

• heavy flavor physics

Generalized Factorization Approach

Pole Dominance Model

Summary

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Effective Hamiltonian: basic tool to study the hadronic decay of heavy flavor mesons

are Wilson coefficients and are four quark operators:

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The amplitude of is

The key is to tackle :

Naïve factorizationGeneralized FactorizationPole dominance modelQCD factorization (QCDF)Perturbative QCD approach (PQCD)Soft-collinear effective theory (SCET)…

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Assumption: the matrix element is factorized into two parts,

Neglect the annihilation and nonfactorization contributions

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for color-favored (T) and color-suppressed (C) processes.

are universal and process independent.

Difficulties: are renormalization scale and scheme

dependentfail to describe the color-suppressed decay

modes due to the smallness of

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Consider non-factorization contributions

In the large-Nc approach,

A large relative strong phase between diagrams is induced by final-state interactions

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Annihilation diagrams are neglected as an approximation in the factorization model.

We will calculate considerable resonant effects of annihilation diagrams in a single pole dominance model.

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Only consider the lowest lying poles Example:

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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

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Annihilation Emission diagrams

Pole Model Generalized Factorization Approach

Consider relative strong phases between topological diagrams

Calculate the branching ratios of and

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, large annihilation type contributions agree with the experiment data better than that of the diagrammatic approach.

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Large annihilation type contributions agree with the experiment data.

The single pole resonance effect dominates the annihilation type contribution in most decay modes.

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Small annihilation contributions in this model

Due to the smallness of decay constants of intermediate scalar mesons.

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and are studied on the basisGeneralized factorization for emission diagramsPole model for resonance effect of annihilation

diagramsRelative strong phases between topological

diagrams

Our results agree with experimental data

Annihilation contributions in pole modelsmall to , but large to

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The amplitudes satisfy the isospin triangle relation

but

Besides, importance of inelastic final state interactions of D meson decays in which on-shell intermediate states will contribute imaginary parts. 29

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